Journal articles: 'Romney and Merino sheep'

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Farrell, Lydia J., Peter R. Tozer, Paul R. Kenyon, Lydia M. Cranston, and Thiagarajah Ramilan. "Producing Higher Value Wool through a Transition from Romney to Merino Crossbred: Constraining Sheep Feed Demand." Agriculture 11, no. 10 (September 25, 2021): 920. http://dx.doi.org/10.3390/agriculture11100920.

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A strategy to increase wool income for coarse wool (fibre diameter > 30 µm) producers through a transition to higher value medium wool (fibre diameter between 25 and 29 µm) was identified, with previous analyses allowing sheep feed demand increases to impractical levels during the transition period. This study modelled a whole flock transition from Romney breed to a ¾Merino¼Romney flock through crossbreeding with Merino sires, with sheep feed demand constrained between 55% and 65% of total grown feed. Transition was complete after 12 years, and the final ¾M¼R flock had higher COS (cash operating surplus; NZD 516/ha) than the base Romney flock (NZD 390/ha). Net present value analyses showed the transition always had an economic benefit (up to 13% higher) over the Romney flock. In a sensitivity analysis with sheep and wool sale prices changed by ±10%, higher sheep sale prices reduced the economic benefit of the transition (NPV up to 11% higher) over the Romney flock, as sheep sales comprised a higher proportion of income for the Romney flock, and higher wool sale prices increased the benefit (NPV up to 15% higher) of the transition to ¾M¼R over the Romney flock. This study demonstrated a whole flock transition from Romney to ¾M¼R breed was profitable and achievable without large variation in sheep feed demand, although the scale of benefit compared to maintaining a Romney flock was determined by changes in sheep and wool sale prices.

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Carles, A. B., and W. A. K. Kipngeno. "The effect of season and the introduction of rams on oestrous activity in Somali, Nandi, Merino, Karakul and New Zealand Romney Marsh ewes in Kenya." Animal Science 43, no. 3 (December 1986): 447–57. http://dx.doi.org/10.1017/s000335610000266x.

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ABSTRACTA study was made of the levels of oestrous activity of two indigenous breeds of sheep (Somali and Nandi) and three exotic breeds of sheep (Merino, Karakul and New Zealand Romney Marsh) over a period of 3 years, in an equatorial environment. Breed was the only significant source of variation for the length of the oestrous cycle (P < 0·01). The mean lengths of the oestrous cycle were 17·2 (s.d. 3·21), 17·5 (s.d. 2·24), 17·9 (s.d. 2·99), 17·5 (s.d. 2·57) and 16·5 (s.d. 3·41) days for the Somali, Nandi, Merino, Karakul and Romney Marsh breeds, respectively.The mean percentage of ewes of the different breeds showing oestrus in 20-day periods were 69·8 (s.d. 22·57), 49·9 (s.d. 18·67), 63·4 (s.d. 25·70), 79·2 (s.d. 20·30) and 33·2 (s.d. 23·50) % for the Somali, Nandi, Merino, Karakul and Romney Marsh breeds, respectively. Time-series analysis did not detect any evidence of seasonal variation in oestrous activity, although there was an indication that the Merino and Romney Marsh breeds showed a marked increase in oestrous activity following, the introduction of rams. It was concluded that the variation in level of oestrous activity was short term and random.

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Edwards, J. E. Hocking, M. J. Birtles, P. M. Harris, A. L. Parry, E. Paterson, G. A. Wickham, and S. N. McCutcheon. "Pre- and post-natal wool follicle development and density in sheep of five genotypes." Journal of Agricultural Science 126, no. 3 (May 1996): 363–70. http://dx.doi.org/10.1017/s002185960007492x.

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SUMMARYThe pre-natal and post-natal development of wool follicles in sheep of five genotypes with contrasting wool types was examined to provide data on which to base studies of physiological factors affecting wool type via follicle development. This study was conducted following Autumn mating in 1992 at Palmerston North, New Zealand (40° S, 176° E). The rate and timing of follicle development in midside skin samples from Romney, Merino, Merino × Romney (M × R), Drysdale and Wiltshire foetuses and lambs collected at weekly intervals from days 76 to 143 of gestation and 1, 3, 7, 12 and 32 weeks after birth were examined.Primary (P) follicle density had a similar pattern of development in each of the genotypes, although the Merino had a significantly greater density of P follicles than the other genotypes. There was a difference in the rate of P follicle maturation between genotypes with the Drysdale, Wiltshire and M × R completing P follicle maturation before the other two genotypes. However, the majority of P follicles in all genotypes were producing fibres by 111 days of gestation. It was concluded that the small differences in the density and time of development of the P follicles could not cause the differences in wool type between genotypes.The pattern of development of the secondary (S) follicle population was examined by comparing S: P ratios. The initiation of S follicles began at similar ages in the five genotypes, but initiation was completed earlier in the Romney, Drysdale and Wiltshire than in the Merino and M × R, as indicated by a significant genotype by age interaction (P < 0·001). There was no difference between genotypes in S:P ratio from 90 to 104 days of gestation. The S:P ratio of the Romney, Drysdale and Wiltshire did not change significantly from 104 days of gestation until the end of the study, indicating that few S follicles were initiated in these genotypes after 104 days of gestation. The M × R data showed a significant increase in S:P ratio until 119 days of gestation and the Merino S:P ratio increased until 126 days of gestation.The period between days 90 and 125 of gestation was identified as being the critical period for the development of different follicle populations in Merino and non-Merino genotypes and it is this period which should be the focus for studies to determine physiological factors controlling secondary follicle development.

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Montgomery, GW, IC Scott, RP Littlejohn, GH Davis, and AJ Peterson. "Concentrations of FSH are elevated in new-born ewe lambs carrying the Booroola F gene but not in lambs from a prolific Romney strain." Reproduction, Fertility and Development 1, no. 4 (1989): 299. http://dx.doi.org/10.1071/rd9890299.

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Concentrations of FSH were measured in new-born lambs in Booroola Merino x Romney and Booroola Merino flocks where the Booroola F gene was segregating, and in progeny from sires of a prolific strain of Romney sheep. FSH concentrations increased with age and liveweight in Booroola Merino x Romney ewe lambs to reach peak concentrations at 4-6 weeks of age. Significantly higher mean concentrations were recorded in ewe lambs homozygous for the Booroola gene (FF) compared with non-carrier (+ +) ewe lambs. Concentrations in heterozygous (F+) ewe lambs were intermediate. Maximum differences between the genotypes were recorded at 6 weeks of age. Significantly higher FSH concentrations were also recorded in F-gene-carrier female lambs when compared to non-carriers in two other flocks. FSH concentrations remained low in ram lambs up to 12 weeks of age, and there were no differences between Booroola genotypes. The progeny of one ram from the prolific Romney family had high ovulation rates at 18 months of age. The progeny of other related rams showed no increase in ovulation rates at 18 months of age. Concentrations of FSH in the high-ovulation-rate progeny at 3 and 5 weeks of age did not differ from those in the low-ovulation-rate progeny, but were lower than those in the progeny of an FF Booroola Merino x Romney ram. These results support the hypothesis that neonatal concentrations of FSH are higher in lambs carrying the Booroola F gene, but not in all prolific strains since high FSH concentrations were not recorded in daughters from a prolific Romney flock.(ABSTRACT TRUNCATED AT 250 WORDS)

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Scobie, D. R., S. R. Young, D. O'Connell, and E. Eythorsdottir. "Skin wrinkles of the sire adversely affect Merino and halfbred pelt characteristics and other production traits." Australian Journal of Experimental Agriculture 45, no. 12 (2005): 1551. http://dx.doi.org/10.1071/ea03202.

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The wrinkles on the skin of Merino sheep and related breeds are retained during leather processing, and the skins are known as ‘ribby pelts’ in the leather trade. Merino sires with either no skin wrinkles (smooth, n = 7) or excessive wrinkles (ribby, n = 7) were allocated at random to mating groups of 22 Merino ewes mixed with 22 Romney ewes. The progeny of ribby sires were more ribby at docking (P<0.001), at shearing (P<0.001), in the fellmongery (P = 0.001) and as pickled pelts (P<0.001). Merino progeny were more ribby than Merino × Romney (halfbred) progeny at all stages. When professionally graded as pickled pelts, smooth-sired progeny produced more pelts without ribs in both Merino (5% v. 0%) and halfbreds (69% v. 38%) than ribby-sired progeny. Wool samples collected at 7.5 months of age were not significantly different between sire groups in mean fibre diameter (P = 0.27) or staple length (P = 0.60) but they were different in standard deviation of fibre diameter (P = 0.003). Liveweight was consistently greater in the progeny of smooth sires, although this difference did not reach significance until the progeny attained a mean liveweight of 28 kg for Merinos and 32 kg for halfbreds (P = 0.016). Breed differences were observed in other traits and these are discussed. Interestingly, there were few significant sire type breed interactions, the exceptions being yield of clean wool (P<0.001), standard deviation of fibre diameter (P = 0.003) and an additional pelt trait referred to as pinhole score (P = 0.003). In summary, choosing sires without skin wrinkles can improve pelt quality, wool quality and liveweight of Merino and halfbred progeny.

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Henkes, Luiz Ernani, Tania de Azevedo Weimer, and José Carlos Ferrugem de Moraes. "BIOCHEMICAL POLYMORPHISMS IN SHEEP AND THEIR POTENTIAL USE FOR PATERNITY TESTS." Ciência Rural 24, no. 3 (December 1994): 579–82. http://dx.doi.org/10.1590/s0103-84781994000300023.

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The genetic variability of 22 protein loci was investigated in two sheep flocks: 22 females Romney Marsh and 124 animals derived from crossbreeding between Romney Marsh and Merino Booroola, reared by the Brazilian Agricultural Research Corporation (Empresa Brasileira de Pesquisa Agropecuária -EMBRAPA, Bagé, RS, Brazil). Eight loci were polymorphic; the others showed no variation. The usefulness of the eight plymorphic systems (Cat, DIA I, EP-1, EsA, HbB, ME, Tf, and X Prot.) in parentage tests was analyzed. The probability to find two random identical animals in each breed was estimated as 1:1000. The efficiency of these proteins for exclusion of one of two possible sires in parentage tests was about 77% both for Romney Marsh and Romney/ Booroola flocks. Although parentage tests in sheep have not been enforced in Brazil up to now, the establishment of this technique is important for the prevention of non-paternity on the excellent rams.

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Li, Wenhao, Hua Gong, Huitong Zhou, Jiqing Wang, Shaobin Li, Xiu Liu, Yuzhu Luo, and Jon G. H. Hickford. "Variation in <i>KRTAP6-1</i> affects wool fibre diameter in New Zealand Romney ewes." Archives Animal Breeding 62, no. 2 (August 13, 2019): 509–15. http://dx.doi.org/10.5194/aab-62-509-2019.

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Abstract. Variation in KRTAP6-1 has been reported to affect wool fibre traits in Merino cross-breed sheep and Chinese Tan sheep, but little is known about whether these effects persist in other breeds. In this study, variation in KRTAP6-1 was investigated in 290 New Zealand (NZ) Romney ewes sired by 16 different rams. Polymerase chain reaction single-stranded conformational polymorphism (PCR-SSCP) analysis revealed four variants (A, B, E and F) of KRTAP6-1, and nine genotypes (AA, AB, AE, AF, BB, BE, BF, EE and FF) in these ewes. Among the 243 ewes that had genotypes with a frequency of over 5 % (i.e. AA, AB and BB), the presence of A was found to be associated with reduced mean fibre diameter (MFD) and increased coefficient of variation in fibre diameter (CVFD), whereas the presence of B had a trend of association with decreased coarse edge measurement (CEM). A genotype effect was also detected for MFD and CVFD. No associations were detected for fibre diameter standard deviation (FDSD), mean fibre curvature (MFC) and medulation. These results suggest that variation in KRTAP6-1 affects wool fibre diameter in NZ Romney ewes, confirming the finding in Merino cross-breed sheep.

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Walling, G. A., K. G. Dodds, S. M. Galloway, A. E. Beattie, E. A. Lord, J. M. Lumsden, G. W. Montgomery, and J. C. McEwan. "The consequences of carrying the Booroola fecundity (FecB) gene on sheep liveweight." Proceedings of the British Society of Animal Science 2000 (2000): 43. http://dx.doi.org/10.1017/s1752756200000442.

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The increase in ovulation rate caused by the Booroola gene was first observed in the Booroola Merino strain of sheep (Davis et al., 1982) and the gene was subsequently mapped to sheep chromosome 6 (OOV6) (Montgomery et al. 1994). The low heritability of fertility traits and the desire to produce more lambs per ewe from meat breeds has lead to many crossbreeding programs seeking to obtain the benefits of the Booroola gene. However, many producers report animals carrying a Booroola allele to be lighter than non-carriers (G. Davis, personal communication). The Booroola Merino strain of sheep is typically lighter than recipient breeds used in the introgression programmes e.g. Romney. This study aims to determine whether the Booroola gene has a pleiotropic effect on liveweight or whether there is any evidence to suggest a closely linked quantitative trait locus (QTL) affecting liveweight that may ‘hitchhike’ with the Booroola gene.

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DOMINIK, S., P. W. HUNT, J. McNALLY, A. MURRELL, A. HALL, and I. W. PURVIS. "Detection of quantitative trait loci for internal parasite resistance in sheep. I. Linkage analysis in a Romney×Merino sheep backcross population." Parasitology 137, no. 8 (April 14, 2010): 1275–82. http://dx.doi.org/10.1017/s003118201000020x.

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SUMMARYThis study aimed to identify putative quantitative trait loci (QTL) that significantly affect internal parasite resistance in a backcross sheep population. A Romney×Merino backcross (to Merino) flock was challenged in 3 separate infections withTrichostrongylus colubriformis(primary and secondary) andHaemonchus contortus(tertiary). Haematological parameters were measured and faecal worm egg counts (FWEC) were established to estimate parasite burden. QTL mapping was conducted for FWEC and for the changes in haematocrit followingH. contortuschallenge and in eosinophil numbers followingT. colubriformischallenge. Animals were genotyped for 55 microsatellite markers on selected chromosomes 2, 3, 6, 11, 13, 15, 21, and 22. Four putative quantitative trait loci were found; these being for eosinophil change in the primary infection (OAR 21), for FWEC in the first infection and eosinophil change in the secondary infection (OAR 3) and for FWEC in the secondary infection (OAR 22). No significant quantitative trait loci were detected for FWEC or haematocrit change during theHaemonchus contortusinfection. The position of the putative quantitative trait loci for eosinophil change on OAR 3 is consistent with other reports of parasite resistance quantitative trait loci, implying some commonality between studies.

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Smith, J. L., I. G. Colditz, L. R. Piper, R. M. Sandeman, and S. Dominik. "Genetic resistance to growth of Lucilia cuprina larvae in Merino sheep." Australian Journal of Experimental Agriculture 48, no. 9 (2008): 1210. http://dx.doi.org/10.1071/ea07301.

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Cutaneous myiasis (fly strike), caused by Lucilia cuprina, is a major ectoparasitic infection of sheep. Previous research has identified contributions of body conformation, wool characteristics and resistance to bacterial dermatoses to resistance to fly strike. This paper investigates whether genetic variation occurs amongst sheep in growth of larvae on skin. Mixed sex Merino sheep in 27 half-sibling groups were challenged with freshly hatched Lucilia cuprina larvae, and survival and growth of larvae were measured after 50 h. Growth but not survival of larvae had moderate heritability (0.29 ± 0.22), comparable to that seen for resistance to nematode parasites in sheep. Phenotypic correlations between resistance to larval growth and wool traits, skin wheal response to intradermal injection of larval excretory secretory products and resistance to internal parasites were negligible; however, there was a significant negative phenotypic correlation with fleece rot score after exposure of sheep to simulated rain at a time independent to that of measurement of larval growth. Larval growth was negatively correlated with peripheral blood eosinophil numbers measured either before or after larval challenge. In addition, larval growth in vitro on serum collected from challenged sheep was moderately associated with larval growth in vivo. A search for quantitative trait loci (QTL) for larval survival and growth was conducted in data from 94 half-sibling progeny of a Merino × Romney sire backcrossed to Merino ewes. Potential QTL for larval growth were identified on chromosome 11 and for larval survival on chromosome 18, although phenotyping greater numbers of sheep and a higher marker density on these chromosomes is necessary to confirm the result. We conclude that this study has identified a novel level of resistance of Merino sheep to growth of L. cuprina larvae that may be mediated in part through actions of anti-larval factors in serum and eosinophils. Further studies are required to establish the impact of growth retardation on the severity of systemic responses of sheep to fly strike and on the biology of adult flies.

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Curran, M. K. "Practical breeding developments and future prospects." BSAP Occasional Publication 14 (January 1990): 13–22. http://dx.doi.org/10.1017/s0263967x00002019.

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AbstractThis paper is a review of practical sheep breeding improvement schemes and techniques in the UK. Recent breed population changes in each of the broad categories of hill, longwool/crossing, longwool ewe, terminal sire and shortwool ewe breeds are outlined. Current or planned improvement programmes are reported for Welsh Mountain, Beulah, Scottish Blackface, Border Leicester, Cambridge, Friesland, Romney, Texel, Suffolk, Lleyn and Merino breeds. The techniques of genetic improvement currently available are discussed including some costs and likely genetic gains; techniques include group breeding schemes, artificial insemination, multiple ovulation and embryo transplant, best linear unbiased prediction and transgenic methods. The application of these techniques and contribution they could make to future sheep improvement are assessed.

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Chai, W., H. Zhou, H. Gong, J. Wang, Y. Luo, and J. G. H. Hickford. "Nucleotide variation in the ovine KRT31 promoter region and its association with variation in wool traits in Merino-cross lambs." Journal of Agricultural Science 157, no. 2 (March 2019): 182–88. http://dx.doi.org/10.1017/s0021859619000406.

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AbstractKeratins are the main structural proteins of wool fibres, and it is thought that variation in the keratins may affect wool fibre characteristics. Polymerase chain reaction-single stranded conformational polymorphism (PCR-SSCP) analyses were used to investigate four regions of the ovine keratin gene KRT31 including a portion of the promoter, the exon 1, exon 3 and exon 7 regions. Initially, in a screening panel of 300 New Zealand Romney, Merino and White Dorper sheep obtained from 26 farms, three, two, two and two PCR-SSCP banding patterns were observed for these four regions, respectively. The promoter region, the exon 1 and exon 3 regions contained two single nucleotide polymorphisms (SNPs) and the exon 7 region contained one SNP. The effect of the variation found in the promoter region on wool traits was subsequently investigated in 485 Southdown × Merino-cross lambs from seven sire-lines. The three variants identified in the original 300 sheep (named A, B and C) were observed with frequencies of 56, 29 and 15%, respectively. The presence of A and B had no significant effect on wool traits, but the presence of C was found to be associated with an increase in greasy fleece weight (GFW), clean fleece weight (CFW) and mean staple length (MSL). There was an effect of genotype on CFW and MSL, with BC sheep producing wool of higher CFW and MSL than AA, AB, AC and BB sheep. These results suggest that ovine KRT31 might be a useful candidate gene for improving wool traits.

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Rosa, H. J. D., P. F. M. Ventura, J. T. Sousa, D. Moreira, A. E. S. Borba, and O. A. Rego. "Productive and reproductive performance of Romney Marsh and Merino Branco sheep in the Azores under different feeding regimens." Small Ruminant Research 67, no. 2-3 (February 2007): 296–301. http://dx.doi.org/10.1016/j.smallrumres.2005.10.009.

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Naqvi, S. M. K., P. Palta, A. Joshi, R. Gulyani, V. Paul, V. P. Maurya, and R. S. Manik. "210INCREASE IN OVULATION RATE AFTER IMMUNIZATION OF MALPURA EWES AGAINST A SYNTHETIC PEPTIDE SEQUENCE OF THE ±-SUBUNIT OF BOVINE INHIBIN." Reproduction, Fertility and Development 16, no. 2 (2004): 226. http://dx.doi.org/10.1071/rdv16n1ab210.

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Unlike many other breeds of sheep (e.g. Boroola, Romney or Merino) which have high fecundity, the Malpura ewe, an Indian breed of sheep, is marked by an ovulation rate of one and a low incidence of twinning. Active immunization against a number of inhibin-based synthetic peptides has been reported to increase ovulation rates in these high fecundity breeds of sheep. The objective of the present study was to explore the possibility of increasing ovulation rates in Malpura ewes by active immunization against a synthetic peptide replica of the N-terminal sequence of the bovine inhibin. Adult Malpura ewes (n=5) were actively immunized against a synthetic peptide that corresponded to the N-terminus of the α-subunit of bovine inhibin [bIα(1–29)Tyr30]. The peptide was conjugated to ovalbumin, with a peptide-to-ovalbumin ratio of around 20 moles mole−1, to increase its antigenicity. Control ewes (n=5) were immunized against ovalbumin. On the day of primary immunization, 400μg of peptide-ovalbumin conjugate or ovalbumin were dissolved in 1mL of isotonic saline, emulsified with an equal volume of Freund’s complete adjuvant and injected at four sites in each ewe. Following this, boosters 1, 2 and 3 were given on Days 28, 56 and 84, respectively, of the experiment (Day 0=day of primary immunization); boosters were 200μg of peptide-ovalbumin conjugate or ovalbumin dissolved in 1mL of isotonic saline and emulsified with an equal volume of Freund’s incomplete adjuvant. Estrus was synchronized by a double injection schedule of PGF2α (7.5mg Lutalyse, once each on Days 35 and 45). The animals were subsequently allowed to undergo normal cyclicity until the end of the experiment. Ovulation rate was determined by counting the number of corpora lutea observed during laparoscopic examinations approximately 5 days after estrus during three estrous cyles following treatment. The ovulation rate between control and immunized groups was compared by repeated measures ANOVA. Immunization of the Malpura ewes against the synthetic peptide sequence of the α-subunit of bovine inhibin [bIα(1–29)Tyr30] increased ovulation rate over 5-fold compared to that of controls (Table 1). In conclusion, we have shown that inhibin-based fecundity vaccines have the potential of increasing ovulation rates in the Malpura breed of sheep. Table 1

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Nagorcka, B. N., A. E. Dollin, and A. J. Ringrose-Voase. "Measurement of fibre density and fibre bundles in the skin of sheep from different breeds." Australian Journal of Agricultural Research 49, no. 1 (1998): 113. http://dx.doi.org/10.1071/a97044.

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A procedure for analysing digitised scanning electron microscope (SEM) images of impressions of sheep skin has been developed and tested. The new technique for measuring fibre densities and fibre bundles was applied to a small number of sheep from the Romney, Border Leicester, and Suffolk breeds, and in fine- and strong-woolled Merinos. Skin impressions were taken from small shaved areas of the skin, and fibres in digitised SEM images of the skin impressions were counted and assigned to bundles. Estimates were made of the density of epidermal follicles, the proportion of these which branch, the number of fibres (follicles) per bundle, and the proportion of skin left bare of follicles. An average distance between neighbouring epidermal follicles, Λ E, was also measured. Λ E was found to be correlated with fibre diameter. The total density of fibres (follicles) in the animals sampled ranged from 10 to 100 follicles/mm2 , and fibre diameter ranged from ~35 to ~15µm. Despite this wide range, all animals examined were observed to have derived (branched) follicles. The fraction of epidermal follicles which branched varied from ~0·15 to ~0·45, and the average number of fibres (follicles) per bundle ranged from 2·2 to 3·8. Λ E was used to calculate an indicator of the fraction of skin which is bare of follicles. This was found to be substantial, varying between 0·4 and 0·7. Measurements were also made using both serial transverse and serial longitudinal skin sections. The results obtained with the different techniques were compared.

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Morris, CA, SM Hickey, and HV Henderson. "The effect of Johne's disease on production traits in Romney, Merino and Merino x Romney-cross ewes." New Zealand Veterinary Journal 54, no. 5 (October 2006): 204–9. http://dx.doi.org/10.1080/00480169.2006.36698.

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Roque, Ana Paula, José Carlos da Silveira Osório, Pedro Osório Jardim, Nelson Manzoni de Oliveira, and Maria Teresa Moreira Osório. "Produção de carne em ovinos de cinco genótipos: 6. Desenvolvimento relativo." Ciência Rural 29, no. 3 (September 1999): 549–53. http://dx.doi.org/10.1590/s0103-84781999000300029.

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O presente estudo objetivou verificar o desenvolvimento relativo dos componentes do peso vivo, da composição regional da carcaça e da composição tecidual da paleta e do quarto em cordeiros das raças Merino Australiano, Ideal, Corriedale, Romney Marsh e Texel. O trabalho foi realizado no Centro de Pesquisa de Pecuária dos Campos Sulbrasileiros (CPPSUL-EMBRAPA) em Bagé/RS. Foram utilizados 50 cordeiros, sendo 10 de cada uma das raças, nascidos e criados até o desmame (10 semanas) em campo nativo. A partir do desmame, foram suplementados (200g/cab/dia) com uma ração contendo 17% de PB e 75% de NDT, oferecida em regime de confinamento até uma semana pós-desmame e a campo até o abate aos 7,5 meses de idade. O estudo do desenvolvimento relativo realizou-se mediante o modelo da equação exponencial: Y = a . x b. O desenvolvimento relativo dos componentes do peso vivo, da composição regional e tecidual dos cordeiros sofreu influência dos genótipos. As raças Merino Australiano, Romney Marsh e Texel, mais pesadas ao abate, apresentaram maior rendimento de carcaça, mas nas raças Ideal e Corriedale, o rendimento de carcaça quente foi semelhante ao do peso vivo. Os componentes do peso vivo nos diferentes genótipos apresentaram-se isogônicos (não significativos), com exceção da cabeça, na raça Romney Marsh e Texel, que apresentou um desenvolvimento precoce e o baço, que na raça Merino Australiano, foi tardio. A região do pescoço, nas raças Corriedale e Romney Marsh, apresentou um desenvolvimento precoce, considerando-se a carcaça fria, e o costilhar na raça Romney Marsh mostrou-se tardio. Os outros cortes apresentaram um desenvolvimento semelhante ao da carcaça fria em todos os genótipos estudados. Com base nos resultados, pode-se afirmar que o peso de abate e das diferentes regiões da carcaça em cordeiros depende do genótipo.

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Reis, PJ. "Variations in the strength of wool fibres - A review." Australian Journal of Agricultural Research 43, no. 6 (1992): 1337. http://dx.doi.org/10.1071/ar9921337.

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This review outlines the factors that may influence the strength of wool fibres and the associated changes in structure and protein composition that have been observed in weakened fibres. The strength of a wool staple is dependent on the intrinsic strength of the fibres that it contains and the total cross-sectional area of fibre being tested. The minimum fibre diameter and the rate of change of diameter along a staple are important determinants of strength. Different sheep kept under similar conditions show a large range of staple strengths. Estimates of heritability for staple strength are sufficiently high (0.17 to 0.49 in Merinos; 0.20 to 0.58 in Romneys) to prompt the establishment of selection programmes in both breeds. A variety of physiological and environmental factors influence the strength of wool fibres. Nutrient supply exerts a major influence via effects on fibre diameter. In addition, there are specific effects of some amino acids (methionine and lysine), trace elements (copper and zinc) and vitamins (folic acid). Seasonal effects are important in breeds which exhibit a large annual rhythm of wool growth, e.g. Romneys, but not in Merinos. Pregnancy and lactation influence fibre strength through competition for essential nutrients but hormonal factors may also be involved. Fibre strength may also be influenced by stress involving excessive secretion of glucocorticoids and by various parasites and diseases which can influence nutrient supply and cause stress. No clear association has been established between the strength of wool fibres and the proportions of the constituent proteins. The content of high-tyrosine proteins in the matrix of weak fibres is frequently, but not invariably, reduced. Likewise, fibre strength has been associated with the proportions of components of the high-sulfur proteins in some studies, but not in others. Thus in Romneys, but not Merinos, tender (weak) wool contained a higher proportion of orthocortex than sound wool, and hence contained less ultra-high-sulfur proteins. Weak fibres produced by specific nutritional treatments in adult sheep and lambs show a loss of cuticle scale pattern and malformed or degraded fibres.

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Woods, JL, and DFG Orwin. "Wool Proteins of New Zealand Romney Sheep." Australian Journal of Biological Sciences 40, no. 1 (1987): 1. http://dx.doi.org/10.1071/bi9870001.

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Proteins extracted from the wool of 65 Romney ewes were analysed qualitatively by one- and twodimensional polyacrylamide gel electrophoresis. Romney wool proteins could be classified into the iow-sulfur, high-sulfur, and high-tyrosine protein groups described for wool from other breeds.

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Farrell, Lydia Jane, Stephen Todd Morris, Paul R. Kenyon, and Peter R. Tozer. "Modelling a Transition from Purebred Romney to Fully Shedding Wiltshire–Romney Crossbred." Animals 10, no. 11 (November 7, 2020): 2066. http://dx.doi.org/10.3390/ani10112066.

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Considering the current low prices for coarse wool (fibre diameter > 30 µm), a grading up transition to a shedding flock may eliminate wool harvesting costs and increase sheep farm profit. This transition could be achieved by breeding non-shedding ewes with Wiltshire rams. A bio-economic system-dynamics model of a pastoral sheep farming enterprise was used to simulate this grading up transition from 2580 Romney ewes to a similarly-sized flock of fully shedding third or fourth cross Wiltshire–Romney ewes. The total annual sheep feed demand was constrained within a ±5% range to minimise disruption to the on-farm beef cattle enterprise. Wool harvesting expenses were eliminated after seven years of transition, and with reduced feed demand for wool growth, the post-transition shedding flocks had more ewes producing more lambs and achieving greater annual profit compared with the base Romney flock. The net present values of transition were 7% higher than the maintenance of the base Romney flock with a farmgate wool price of $2.15/kg. Results suggest that coarse wool-producing farmers should consider a grading up transition to a shedding flock, and the collection of data on the production of Wiltshire–Romney sheep in New Zealand would improve the accuracy of model predictions.

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Hopkins, D. L., P. J. Walker, J. M. Thompson, and D. W. Pethick. "Effect of sheep type on meat and eating quality of sheep meat." Australian Journal of Experimental Agriculture 45, no. 5 (2005): 499. http://dx.doi.org/10.1071/ea03176.

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The effect of type of lambs and hoggets on eating quality was evaluated using the M. longissimus lumborum (LL) and the M. biceps femoris (BF) from 210 animals. The animals comprised 7 types as follows: Poll Dorset or White Suffolk × (Border Leicester × Merino) (second cross unweaned lambs, mixed sex, 3–5 months of age); Poll Dorset × (Border Leicester × Merino) (second cross weaned lambs, mixed sex, 9–12 months of age); Border Leicester × Merino (BLM; first cross weaned lambs, mixed sex, 9 months of age); Poll Dorset or White Suffolk × Merino (PDM; first cross weaned lambs, wethers, 12 months of age); Merino × Merino (weaned wether lambs, 9–12 months of age); Border Leicester × Merino (BLM; first cross hoggets, mixed sex, 20 months of age); and Poll Dorset or White Suffolk × Merino (PDM; first cross hoggets, wethers, 16 months of age). The animals were sourced from a number of different properties in New South Wales (NSW) (n = 120) and Victoria (n = 90). Each carcass was subjected to high voltage stimulation (700 V) within 1 h of slaughter. All meat was aged for 5 days before freezing and was subsequently tested by consumers on a 0–100 scale for a number of attributes after cooking using a grilling procedure. The LL from sucker lambs had the lightest colour (highest L* values) with the hoggets having the darkest colour in the NSW group with differences less apparent in the Victorian group. Muscle from first cross and Merino weaned lambs had consistently higher pH levels across the 3 muscles tested (LL; M. semimembranosus; M. semitendinosus) for the NSW group with no differences detected in the Victorian group. LL meat from second cross sucker and first cross (BLM and PDM) weaned lambs had the highest overall liking score, with that from second cross weaned lambs, BLM hoggets and Merino lambs scored as intermediate, while meat from the PDM hogget group had the lowest overall liking score. A similar outcome was found for the other sensory attributes with differences between types being lower for juiciness compared with overall liking scores but they were of a similar ranking. For the BF there was some re-ranking of the overall liking scores compared with the LL, with meat from suckers and first cross PDM lambs and hoggets being intermediate in score while second cross weaned lambs and first cross BLM lambs had the highest scores. The BF from hoggets (BLM) and Merino lambs were given the lowest scores. The lower juiciness score for sucker BF contributed to this change in ranking compared with the LL.

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Oliveira, Nelson Manzoni de, José Carlos Osório, and Eliane Mattos Monteiro. "Produção de carne em ovinos de cinco genótipos: 1. Crescimento e desenvolvimento." Ciência Rural 26, no. 3 (December 1996): 467–70. http://dx.doi.org/10.1590/s0103-84781996000300022.

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O trabalho foi realizado no Centro de Pesquisa de Pecuária dos Campos Sulbrasileiros - CPPSUL - EMBRAPA de Bagé, RS, nos anos de 1994/95, com cordeiros das raças Texel, Romney Marsh, Corriedale, Ideal e Merino nascidos e criados até o desmame (10 semanas) em campo nativo, (predominância de Paspalum notatum Flügge e Axonopus affïnis Chase). Objetivou estudar aspectos relativos ao crescimento e desenvolvimento, com suplementação alimentar a campo, até o abate aos 7,5 meses de idade. A partir do desmame, iniciou-se a suplementaçào dos cordeiros (10 por raça, recebendo 200 g/cab./dia) com uma ração contendo 17% de PB e 75% de NDT. Até uma semana pós-desmame a ração foi oferecida em regime de confinamento e. após, a campo até o abate. Os resultados mostraram que os pesos ao nascer foram semelhantes (P>0,05), porém, do desmame e a partir deste, o crescimento ponderal e o desenvolvimento de cordeiros Texel e Romney Marsh foram sempre superiores aos de Corriedale, Ideal e Merino. Após o desmame, principalmente nos primeiros 45 dias, a capacidade de conversão dos alimentos (suplemento + pasto) foi maior nas raças Texel, Romney Marsh e Ideal. Em todos os genótipos, observou-se que as variações de peso corporal (em relação ao tempo), após os 5,5 meses de idade, pouco contribuíram no peso final de abate.

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Bennett, G. L., and R. A. Field. "A note on the influence of breed and sire differences on iron and zinc concentration of lamb muscle." Animal Science 41, no. 3 (December 1985): 421–24. http://dx.doi.org/10.1017/s0003356100036503.

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AbstractLambs from Perendale, Merino × Perendale, Romney, Merino × Romney and Coopworth ewes, and Southdown and Suffolk sires were assigned to three groups. Groups received no treatment, nine weekly doses of 175 mg iron (Fe) per kg body weight or nine weekly doses of 175 mg zinc (Zn) per kg body weight. They were slaughtered 1 week after the last dose. Samples of m. longissimus were analysed for Fe and Zn concentration.Muscle Zn concentration was greater for Southdown-sired lambs (85·5 mg/kg dried muscle) than for Suffolk-sired lambs (77·6 mg/kg; P < 0·01). Dam genotypes and the interaction of sire breed and dam genotype were not significant for Zn concentration. Heritability of muscle Zn concentration was estimated to be 0·92 (s.e. 0·48). Muscle Fe concentration showed a significant interaction between sire breed and dam genotype (P < 0·05). Heritability of muscle Fe was estimated to be 0·21 (s.e. 0·38). No significant interactions of either sire breed or dam breed × treatment were found.

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Osório, José Carlos, Nelson Manzoni de Oliveira, Pedro Osório Jardim, and Eliane Mattos Monteiro. "Produção de carne em ovinos de cinco genótipos: 2. Componentes do peso vivo." Ciência Rural 26, no. 3 (December 1996): 471–75. http://dx.doi.org/10.1590/s0103-84781996000300023.

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O estudo foi realizado com o objetivo de quantificar e comparar o peso vivo ao abate e seus componentes em cordeiros das raças Merino, Ideal Corriedale, Romney Marsh e Texel. Foram abatidos 50 cordeiros, sendo dez de cada raça, com idade de 225 dias. Os animais foram criados em condições extensivas de campo nativo até o desmame (10 semanas), na região sul do Brasil (Bagé, RS) e castrados aos 30 dias de idade. A partir do desmame, iniciou-se a suplementação dos cordeiros (200g/cab./dia) com uma ração contendo 17% de proteína bruta e 75% de nutrientes digestíveis totais. Até uma semana pós-desmame, a ração foi oferecida em regime de confinamento e, após, a campo até o abate. O genótipo apresentou um efeito sobre os componentes do peso vivo. Entretanto, pode ocorrer de não se detectar diferença entre genótipos em valores absolutos e existir diferença em valores percentuais (caso da cabeça), ou ser verificado diferenças entre alguns componentes do peso vivo em valores absolutos e não em valores percentuais (caso que ocorreu para coração, pulmões e fígado). A raça Texel apresentou valores absolutos superiores em relação às raças Merino Ideal, Corriedale e Romney Marsh. Porém, em valores percentuais, com exceção da carcaça, que igualmente apresentou maior valor, nos demais componentes não foram superiores. A raça Merino e a Ideal apresentaram uma percentagem de pele superior às demais raças.

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Oliveira, Nelson Manzoni de, José Carlos da Silveira Osório, and Eliane Mattos Monteiro. "Produção de carne em ovinos de cinco genótipos: Composição regional e tecidual." Ciência Rural 28, no. 1 (March 1998): 125–29. http://dx.doi.org/10.1590/s0103-84781998000100021.

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O trabalho foi realizado no Centro de Pesquisa de Pecuária dos Campos Sulbrasileiros - CPPSUL/EMBRAPA, Bagé, RS (fase de campo) e no Departamento de Zootecnia da Universidade Federal de Pelotas - UFPEL, Pelotas, RS (fase laboratorial), durante os anos de 1994/95. Utilizaram-se cordeiros das raças Texel, Romney Marsh, Corriedale, Ideal e Merino (10 animais por raça), criados em pastagem nativa (predominância de Paspalum notatum Flügge e Axonopus affinis Chase), recebendo, do desmame às 10 semanas até o abate aos 7,5 meses de idade, 200g/cab/dia de um concentrado com 17% de PB e 75% de NDT, que incluía resíduos da agroindústria em sua formulação. Objetivou-se avaliar o peso de carcaça fria, gordura de cobertura e estado de engraxamento, bem como a composição regional da carcaça (peso dos principais cortes) e tecidual do quarto e paleta (percentual de osso, músculo e gordura na peça). Os resultados mostraram que, com excessão do peso da costela e percentagem de gordura da paleta, as diferenças raciais influenciaram significativamente tanto o peso de carcaça fria e seu estado de engraxamento, quanto as composições regional e tecidual. Houve maior peso de carcaça dos cordeiros Texel, seguido pelos Romney. As carcaças das demais raças foram mais leves e semelhantes em peso (P>0,05). Os cordeiros Merino apresentaram maior percentagem de paleta, as quais foram semelhantes para as demais raças. Os cordeiros Texel apresentaram significativamente menor percentagem de pescoço do que os cordeiros Merino. Quanto à percentagem de quarto, somente os cordeiros Merino mostraram significativamente (P<0,05) menor valor que os Texel, o qual foi semelhante às demais raças. Não houve diferença significativa (P>0,05) para o percentual de costela entre os genótipos. As carcaças dos cordeiros Romney, Corriedale e Merino apresentaram menor gordura de cobertura e obtiveram mais baixos escores de estado geral de engraxamento. Quanto a composição tecidual, os cordeiros Texel e Ideal apresentaram menor percentual de osso no quarto, porém, os primeiros com maior percentagem de músculo. Isto ocorreu associado à menor quantidade de gordura da raça Texel nesta peça. Os cordeiros Texel tiveram menor percentagem de osso e maior percentagem de músculo (P<0,05). As demais raças foram semelhantes em valores (P>0,05). Entre os diferentes genótipos, não houve diferença (P>0,05) em termos de gordura na paleta.

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Oliveira, Nelson Manzoni de, José Carlos da Silveira Osório, Arturo Selaive-Villarroel, Daniel Benitez-Ojeda, and Marcos Flávio da Silva Borba. "Produção de carne em ovinos de cinco genótipos. 5. Estimativas de qualidade e peso de carcaça através do peso vivo." Ciência Rural 28, no. 4 (December 1998): 665–69. http://dx.doi.org/10.1590/s0103-84781998000400021.

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O trabalho foi realçado no CPPSUL/EMBRAPA, Bagé, RS, com a participação (fase laboratorial) da FAEM/UFPel, Departamento de Zootecnia, Pelotas, RS, nos anos de 1994/96. Utilizou-se 117 cordeiros das raças Texel (n=26), Romney Marsh (n =24), Corriedale (n =26), Ideal (n =23) e Merino (n=18), nascidos e criados até o desmame (10 semanas) em campo nativo (predominância de Paspalum notatum Flügge e Axonopus affinis Chase). Objetivou-se examinar as associações existentes entre o peso vivo de abate com o peso de carcaça fria e com alguns indicativos de qualidade da carcaça. A partir do desmame, iniciou-se a suplementaçào dos cordeiros (200 g/cab./dia) com ração contendo 17% de PB e 75% de NDT, formulada a partir de farelo de arroz gordo e desengordurado, capim arroz, sorgo, ureia, farinha de osso, sal mineral e comum. Até uma semana pós-desmame, a ração foi oferecida em regime de confinamento e, após, a campo até o abate aos 7,5 meses de idade. Os resultados obtidos mostraram não ter havido diferença (P>0,05) entre os coeficientes de regressão de peso de carcaça fria sobre peso vivo, porém, houve diferença (p<0,05) na altura das linhas de regressão, proveniente de um maior deslocamento da linha nas raças Texel e Romney Marsh. O estado de engorduramento da carcaça não foi significativo (P>0,05) com o aumento de peso vivo nas raças Merino e Ideal e a espessura de gordura de cobertura variou significativamente (P<0,05) somente na raça Romney Marsh. A conformação da carcaça foi afetada significativamente (P<0,01) nas raças Corriedale e Romney Marsh. Os valores dos coeficientes de regressão observados para as raças Ideal e Texel estiveram próximos, porém, não significativos (P>0,05). A compacidade de carcaça foi significativamente dependente de aumentos de peso vivo nas raças Ideal (P<0,05), Corriedale, Romney Marsh e Texel (P<0,01).

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HARPER, PAW, and AG MORTON. "Neuroaxonal dystrophy in Merino sheep." Australian Veterinary Journal 68, no. 4 (April 1991): 152–53. http://dx.doi.org/10.1111/j.1751-0813.1991.tb03162.x.

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GLASTONBURY, JRW, and CM VENNING. "Ameloblastoma in a Merino Sheep." Australian Veterinary Journal 76, no. 2 (February 1998): 127–28. http://dx.doi.org/10.1111/j.1751-0813.1998.tb14545.x.

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Jolly, RD, and AC Johnstone. "Segmental axonopathy of Merino sheep." New Zealand Veterinary Journal 53, no. 1 (February 2005): 94. http://dx.doi.org/10.1080/00480169.2005.36484.

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Gautrais, Jacques, Pablo Michelena, Angela Sibbald, Richard Bon, and Jean-Louis Deneubourg. "Allelomimetic synchronization in Merino sheep." Animal Behaviour 74, no. 5 (November 2007): 1443–54. http://dx.doi.org/10.1016/j.anbehav.2007.02.020.

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Islamov, E., G. Kulmanova, B. Kulataev, D. Bekbaeva, D. Darkenbayuly, and P. Kulemetova. "IMPROVEMENT OF MEAT QUALITIES OF KAZAKH MEAT-WOOL SEMI-FINE SHEEP BY USING THE ROMNEY-MARSH BREED." Scientific Notes Kazan Bauman State Academy of Veterinary Medicine 248, no. 4 (December 1, 2021): 78–81. http://dx.doi.org/10.31588/2413-4201-1883-248-4-78-81.

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This article presents the results of the first stage of research work on the use of the Romney March gene pool of sheep breed based on the laparascopic method of insemination of Kazakh meat-wool semi-fine sheep. The work was performed within the framework of scientific and technical program: "Development of effective methods of selection by branches of animal husbandry for 2018-2020", on task "Development of effective methods of selection in sheep breeding (application of genetics of Romney marsh breed).

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Blair, H. T., D. J. Garrick, A. L. Rae, and G. A. Wickham. "Selection responses in New Zealand Romney sheep." New Zealand Journal of Agricultural Research 28, no. 2 (April 1985): 257–64. http://dx.doi.org/10.1080/00288233.1985.10420936.

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Shariflou, MR, CM Wade, PA Windsor, I. Tammen, JW James, and FW Nicholas. "Lethal genetic disorder in Poll Merino/Merino sheep in Australia." Australian Veterinary Journal 89, no. 7 (June 22, 2011): 254–59. http://dx.doi.org/10.1111/j.1751-0813.2011.00789.x.

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Ranilla, M. J., S. López, F. J. Giráldez, C. Valdés, and M. D. Carro. "Comparative digestibility and digesta flow kinetics in two breeds of sheep." Animal Science 66, no. 2 (April 1998): 389–96. http://dx.doi.org/10.1017/s1357729800009528.

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AbstractA study was conducted to compare apparent digestibility and digesta flow kinetics in the whole digestive tract in two breeds of sheep (Churra and Merino) offered alfalfa hay at about maintenance. Ten mature sheep (five Churra and five Merino) each fitted with a rumen cannula were used in the study. Apparent digestibility was determined by total faecal collection. Liquid (Co-EDTA) and solid (Cr-mordanted fibre) markers were used to estimate rumen volumes and digesta flows. There were no significant differences between Churra and Merino sheep either in dry-matter or fibre apparent digestibility (P > 0·05). Liquid and solid passage rates did not differ between breeds and the estimated total mean retention times were similar for both genotypes. The volume of liquid in the rumen was proportionately 0·14 greater in Churra than in Merino sheep, although the difference was not significant. Estimated saliva secretion was greater in Churra (11·6 (s.e. 0·77) I/day) than in Merino sheep (10·5 (s.e. 0·72) I/day) but the difference did not reach statistical significance. Solid contents of the rumen did not differ between breeds. Rumen particle density was lowest at 2 h after feeding and remained stable at other sampling times, with no significant differences between breeds. There were no significant differences between breeds in the urinary excretion of total purine derivatives but urinary excretion of allantoin and microbial nitrogen supply tended to be higher in Merino than in Churra sheep (P < 0·20). This was attributed to the smaller rumen pool size of Merino (8·0 (s.e. 0·62) kg) compared with Churra sheep (9·2 (s.e. 0·63) kg). The study indicated that there were no apparent breed differences between Churra and Merino sheep in digestibility and digesta passage when they were given a good-quality forage at a low level of intake.

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Greeff, J. C., L. Bouwer, and J. H. Hofmeyr. "Biological efficiency of meat and wool production of seven sheep genotypes." Animal Science 61, no. 2 (October 1995): 259–64. http://dx.doi.org/10.1017/s1357729800013783.

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AbstractOne hundred and thirty-two ewes of the Merino (M), Finn × Merino (FLXM), Border Leicester × Merino (BLXM), Bleu de Maine × Merino (BMXM), Texel × Merino (TXM), Cheviot × Merino (ChXM) and Merino Landsheep × Merino (MLXM) were evaluated for efficiency of lamb production. Individual food intakes of every ewe and also of her lamb(s) were determined over a complete production cycle. Efficiency of lamb production (kg lamb marketed at 35 kg live mass per kg food consumed by the ewe and her lamb(s)) indicated that the FLXM was the most efficient, followed by the TXM, Merino, MLXM, BLXM, ChXM and the BMXM was the least efficient. No significant differences (P < 0·05) were found between genotypes for efficiency of lamb production for ewes producing and rearing singletons until 35 kg live mass with ewe mass included as a covariate. Efficiency of wool production of the Merino was significantly (T < 0·001) higher than that of the other crosses. These results emphasize the importance of reproduction traits in improving efficiency of lamb production.

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Szabó, Mária, Szilvia Kusza, István Csízi, and István Monori. "The status of the Hungarian Merino sheep breed compared to the other merino breeds." Acta Agraria Debreceniensis, no. 69 (March 23, 2016): 151–56. http://dx.doi.org/10.34101/actaagrar/69/1804.

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Merino and Merino-derived sheep breeds have been widely known and distributed across the world, both as purebred and admixed populations. They represent a diverse genetic resource which over time has been used as the basis for the development of new breeds. In spite of this, their gene-pool potential is still unexplored. The Merino sheep represent the most important sheep resource of the Hungarian husbandry. It has the largest amount of individuals between both of the stock and commercial flocks. But in Europe the Merino stocks went through a drastic reduction in number. Thus these breeds became endangered in several countries as well as in Hungary. In this study we would like to present the recent status of different Merino breeds of the world to ground our further phylogenetic research with the Hungarian Merino breed.

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Forrest, JW, MR Fleet, and GE Rogers. "Characterization of Melanocytes in Wool-bearing Skin of Merino Sheep." Australian Journal of Biological Sciences 38, no. 3 (1985): 245. http://dx.doi.org/10.1071/bi9850245.

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The distribution and character of melanocytes in the wool-bearing skin of Merino sheep of known genotypes were examined by light and electron microscopy. In black Merino sheep (ww, homozygous recessive), melanocytes were localized within three regions of the skin: epidermal-dermal border, outer root sheath and follicle bulb. Melanocytes within these regions were found to be actively producing melanin, had numerous dendritic extensions and were able to transfer melanin to adjacent keratinocytes. In a black Merino sheep whose fibres were white due to an experimentally induced copper deficiency the melanocytes were amelanotic. In contrast, for both WW (homozygous dominant) and Ww (heterozygous) white Merino sheep melanocytes were observed only at the epidermal-dermal border of the epidermis. The melanocytes appeared also to differ in character containing less melanin, appearing less dendritic in shape and having a reduced ability to transfer melanin to adjacent keratinocytes. The gene for white fleece (W), therefore, appears able to regulate pigmentation in Merino sheep, at least in part, by controlling the location and activity of melanocytes within the wool-bearing skin.

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Sturges, Mark. "Fleecing Connecticut: David Humphreys and the Poetics of Sheep Farming." New England Quarterly 87, no. 3 (September 2014): 464–89. http://dx.doi.org/10.1162/tneq_a_00395.

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At the turn of the nineteenth century, the importation of a Spanish breed of merino sheep to the United States led to a dramatic period of agricultural intensification. Profiling David Humphreys, who promoted merino sheep in poetry and prose, this essay interprets the merino boom as a lesson in the dangers of rhetorical and environmental manipulation.

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McPhee, M. J., D. L. Hopkins, and D. W. Pethick. "Intramuscular fat levels in sheep muscle during growth." Australian Journal of Experimental Agriculture 48, no. 7 (2008): 904. http://dx.doi.org/10.1071/ea08046.

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A 5 × 4 factorial experiment was designed in which lambs representing five genotypes were slaughtered at four ages (110, 236, 412 and 662 days of age). The genotypes represented were Poll Dorsetgrowth × Border Leicester Merino, Poll Dorsetgrowth × Merino, Poll Dorsetmuscling × Merino, Merino × Merino and Border Leicester × Merino. Both sexes (ewes and wethers) were represented for each genotype and slaughter age combination. In total, 595 animals were slaughtered and the carcass composition and intramuscular fat were measured. Carcass composition [fat, ash and protein (lean)] was determined by dual energy X-ray absorptiometry, with the intramuscular fat percentage determined using near-infrared spectroscopy following removal and weighing of the entire longissimus thoracis et lumborum (LL) muscle. Analysis revealed that the proportion of intramusular fat in the loin relative to total carcass fat decreases as animals mature, thus indicating that intramusular fat deposition occurs early in the maturation of sheep. Furthermore, as animals became heavier and older the accretion rate of intramuscular fat in the LL muscle slowed down. Both genotype (P < 0.05) and sex (P < 0.001) were found to impact on this pattern, with Border Leicester × Merino animals exhibiting the largest increase in intramuscular fat proportion in the LL muscle (4.92 and 5.50% at 22 months of age for ewes and wethers, respectively). The Poll Dorsetgrowth × Border Leicester Merino animals were found to have the greatest absolute levels of intramuscular fat in the whole LL muscle (80.95 and 97.60 g at maturity for ewes and wethers, respectively). The amount of intramuscular fat significantly increased as the sheep became older and fatter; however, these differences were quantitatively small. As such, finishing prime lambs to high levels of total carcass fatness would have little effect on any eating quality benefits associated with increased intramuscular fat proportion.

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Davis, G. H., C. A. Morris, and K. G. Dodds. "Genetic studies of prolificacy in New Zealand sheep." Animal Science 67, no. 2 (October 1998): 289–97. http://dx.doi.org/10.1017/s1357729800010055.

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AbstractData on ovulation rate, embryo survival and litter size have been analysed from the 1988-96 records collected at AgResearch's Woodlands Research Station on 2180 elite (highly prolific) ewes of three breeds: Romney, Coopworth and Perendale. The Romneys included a subgroup found to carry the sex-linked Inverdale high prolificacy gene. Foundation animals for all breeds were screened on high litter size (lambs born, alive or dead, per ewe lambing) from industry flocks. Prior to being transferred to Woodlands between 1979 and 1984, their average litter size was 2·66. Ovulation rates for descendants of the foundation ewes averaged 2·15 (Romney), 2·43 (Coopworth), 2·15 (Perendale) and 2·96 for the Romney subgroup carrying the Inverdale gene. Embryo survival averaged 0·84 except for a low value in Inverdales (0·76). Using a restricted maximum likelihood model, with full relationship matrix, the within-breed heritability of ovulation rate over all ages and breeds (excluding Inverdale) was 0·14 (s.e. 0·03), with repeatability 0·26 (s.e. 0·02). Litter size averaged 1-80 (Romney), 2·05 (Coopworth), 1·76 (Perendale) and 2·17 (Inverdale). The heritability estimate for litter size (excluding Inverdale) was 0·073 (s.e. 0·018), from data for all ages. The genetic correlation between ovulation rate and litter size was 0·91 (s.e. 0·08). The standard deviation for ovulation rate in the Inverdales was 1·75 times as great as the average of the other three breeds. Embryo survival to term for ewes conceiving to two, three or four ovulations averaged 0·89, 0·77 and 0·64, respectively, and was significantly different among breeds fP < 0·001). The greater ovulation rate in Inverdales than Romneys was sufficient to explain the Inverdale effect on reduced embryo survival. The highest embryo survival was observed in the Coopworth breed (P < 0·001).

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NEGOVORA, V. F. "UNIQUE PROPERTIES OF MERINO SHEEP WOOL." Sheep, goats, woolen business, no. 1 (2021): 52–53. http://dx.doi.org/10.26897/2074-0840-2021-1-52-53.

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Parsons, Y. M., D. W. Cooper, L. R. Piper, Y. M. Parsons, and D. W. Cooper. "Genetic variation in Australian Merino sheep." Animal Genetics 27, no. 4 (April 24, 2009): 223–28. http://dx.doi.org/10.1111/j.1365-2052.1996.tb00482.x.

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COOK, RW, RD JOLLY, DN PALMER, I. TAMMEN, MF BROOM, and R. McKINNON. "Neuronal ceroid lipofuscinosis in Merino sheep." Australian Veterinary Journal 80, no. 5 (May 2002): 292–97. http://dx.doi.org/10.1111/j.1751-0813.2002.tb10847.x.

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Morera, L., D. Llanes, M. Barbancho, and A. Rodero. "Genetic polymorphism in Spanish Merino sheep." Animal Blood Groups and Biochemical Genetics 14, no. 2 (April 24, 2009): 77–82. http://dx.doi.org/10.1111/j.1365-2052.1983.tb01064.x.

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GLASTONBURY, J. R. W., R. I. WALKER, D. J. KENNEDY, P. A. GILL, K. W. McDOUGALL, and A. G. SHARROCK. "Dieldrin toxicity in housed Merino sheep." Australian Veterinary Journal 64, no. 5 (May 1987): 145–48. http://dx.doi.org/10.1111/j.1751-0813.1987.tb09665.x.

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Trukhachev, V., O. Yatsyk, E. Telegina, A. Krivoruchko, H. Zhou, and J. G. H. Hickford. "Comparison of the myostatin (MSTN) gene in Russian Stavropol Merino sheep and New Zealand Merino sheep." Small Ruminant Research 160 (March 2018): 103–6. http://dx.doi.org/10.1016/j.smallrumres.2018.01.005.

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Niżnikowski, Roman, Marcin Świątek, Żaneta Szymańska, Magdalena Ślęzak, and Krzysztof Głowacz. "Polymorphism of the prion protein gene (PRNP) in Polish Merino and Suffolk sheep flocks." Roczniki Naukowe Polskiego Towarzystwa Zootechnicznego 16, no. 2 (June 30, 2016): 9–21. http://dx.doi.org/10.5604/01.3001.0014.2015.

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The aim of the study was to investigate the distribution of prion protein PRNP alleles in flocks of Polish Merino and Suffolk sheep. The research was conducted in 2012-2017 on ewes and rams kept in the Golina Wielka sheepfold (Greater Poland Voivodeship, Poland). All animals (264 ♀ and 64 ♂ Polish Merino; 98 ♀ and 73 ♂ Suffolk) were up to one year old. PRNP gene polymorphism was identified in the sheep. The frequency of scrapie alleles and genotypes was found to be highly significantly influenced by the breed and significantly influenced by the year in the case of Polish Merino sheep. Five alleles (ALRR, ALRQ, ALHQ, AFRQ and VLRQ) were detected in Polish Merino sheep, leading to the identification of 10 PRNP genotypes. In the Suffolk breed, three alleles (ALRR, ALRQ and ALHQ) and three genotypes were identified. In the Polish Merino breed, the frequency of the ALRR/ALRQ genotype was high and was the highest among all genotypes, followed by ALRR/ALRR. The level of genotypes containing valine at codon 136 was very low. In the Suffolk breed, the frequency of the ALRR/ALRR genotype was very high, and there were no alleles with valine at codon 136. In addition, in Polish Merino sheep, phenylalanine at codon 141 was detected only in the AFRQ allele, which appeared in two genotypes (in combination with ALRR and ALRQ).

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Knight, T. W., M. Gibb, and E. Sorensen. "Comparison of the behaviour of Romney and Merino ewes lambing on slopes." New Zealand Journal of Agricultural Research 33, no. 3 (July 1990): 497–98. http://dx.doi.org/10.1080/00288233.1990.10428448.

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Fleet, M. R., M. J. Bennie, G. N. Dunsford, G. R. Cook, and D. H. Smith. "Lamb production from Merino ewes mated to Merino or Damara rams." Australian Journal of Experimental Agriculture 42, no. 8 (2002): 1027. http://dx.doi.org/10.1071/ea01073.

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Damara sheep have recently been imported to Australia and are being crossed with Merino ewes as a diversification from wool to fat tail sheep production for live sheep export or meat markets. A comparison was made of the lamb outputs from Merino ewes mated to 2 Merino rams and 2 Damara fat tail rams. There were more multiple litters produced in the matings with the Damara rams than from the Merino rams (P = 0.01). The 5-month weights of the crossbred lamb groups (36.3 and 38.9 kg) were higher (P<0.05) than the Merino groups (33.4 and 32.3 kg). Ram lambs were slaughtered at 7 months of age and the carcasses dissected into 'trim lamb' lean portions, fat trims, bone and other oddments. Dressing percentage at slaughter of the crossbred lambs was 3–4% higher (P<0.001), reflecting lower wool production, than the Merino lambs. After adjustment for chilled carcass weight, there were no differences (P>0.05) between rams for the total amount of lean meat. However, the crossbred groups had more external carcass fat (2.59 and 2.64 kg) than the Merino groups (2.14 and 2.15 kg) and, in addition, had fat tail weights of 0.52 and 0.36 kg.

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Hohenboken, W. D., J. N. Clarke, P. V. Rattray, J. F. Smith, and M. Wheeler. "Responsiveness of ewe genotypes to varying nutritional management, and conventional genotype × environment interactions in sheep." Animal Science 47, no. 2 (October 1988): 253–62. http://dx.doi.org/10.1017/s0003356100003330.

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ABSTRACTAn experiment was conducted during 2 years to evaluate industry Coopworth, industry Romney and Waihora Romney ewes (a strain selected for 10 years for increased ewe productivity) in a variety of nutritional and management treatment combinations. Waihora Romneys were most productive with small and inconsistent differences between industry Romneys and Coopworths. Conventional cross-classified analyses of variance did not reveal large, consistent nor economically important ewe genotype × nutritional treatment or year interactions. Additional analyses were designed to investigate whether the ewe genotypes responded to changes in the nutritional and(or) management environment with similar quantitative changes in production. A sensitive genotype would be one that responded to environmental changes with relatively large changes in productivity; a stable genotype would be one whose changes in production in response to a variable environment were smaller. By several statistical procedures designed to assess relative ‘sensitivity’ v. ‘stability’, Waihora Romney ewes appeared to be the most stable, with industry Romney and Coopworth ewes similar in their sensitivity.

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Journal articles on the topic 'Romney and Merino sheep'

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