Dissertations / Theses on the topic 'COWs'

Bacterial and fungal culturing was conducted on samples taken from the vaginal fornix of 106 cows, of which 42 had vaginitis and 64 had normal vaginas. The diagnosis of vaginitis and non-vaginitis samples was determined by histologic examination. Aerobic, anaerobic, and microaerophilic cultures were done. In addition, cultures were performed for Campylobacter sp., Ureaplasma sp., Mycoplasma sp., Tritrichomonas foetus, and fungi. All 106 samples contained mixed aerobic bacterial cultures. The more frequent aerobic isolates included Acinetobacter lwoffii, Arcanobacterium pyogenes, Escherichia coli, Corynebacterium spp., and Streptococcus spp. These organisms were isolated from both groups of cows, but more frequently from the vaginitis group. Anaerobic isolates included Peptostreptococcus spp., Prevotella spp., and Fusobacterium spp. The fungal isolates included Aspergillus sp., Mucor sp., and Penicillium sp.

Doctor of Philosophy
Department of Animal Sciences and Industry
Jeffrey S. Stevenson
Four experiments were conducted in beef cows to determine factors that increased the probability of pregnancy per AI when cows are inseminated by appointment. Cows in all experiments were inseminated after a 7-d CO-Synch + CIDR program (100 μg GnRH [2 mL Factrel, Pfizer Animal Health, Whitehouse Station, NJ] 7 d before 25 mg PGF₂[subscript]α [d 0; 5 mL Lutalyse; Pfizer Animal Health]). Experiment 1 compared 1 vs. 2 inseminations and GnRH injection times at 60 and 75 h after the CO-Synch + CIDR program. Delaying AI until 75 h, according to interpretation of estrus-detection patches, for cows not in estrus by 60 h after CIDR insert removal increased (P < 0.05) pregnancy risk (PR) compared with cows not in estrus and inseminated at 60 h (51.4 vs. 41.7%), respectively. The necessity of GnRH injection concurrent with AI was tested in experiment 2. Cows displaying estrus by 65 h that were injected with GnRH had similar PR to cows in estrus and not treated with GnRH (61.9 vs. 60.4%), respectively. Cows in experiment 2 that did not display estrus, but were treated with a GnRH injection at 65 h and then inseminated at 84 h after CIDR insert removal had increased PR compared with similar cows not treated with GnRH (33.4 vs. 15.0%; P < 0.01), respectively. Experiments 3 and 4 were observational studies conducted to determine if blood metabolites glucose and beta-hydroxy butyrate (BHB experiment 3), or physical body and blood metabolites, (glucose, BHB, non-esterified fatty acids [NEFA], blood urea nitrogen [BUN], body weight, rump fat [RF], or BCS; experiment 4) were indicative of future reproductive success in suckled beef cows enrolled in a timed AI program. In experiment 3, plasma glucose concentration 10 d before AI was lesser (P = 0.01; 52.2 vs. 56.9 mg/dL) and serum BHB concentration was lesser (P < 0.01) in cows that became pregnant 35 d after timed AI than for cows that did not become pregnant (600 vs. 690 μM), respectively. Experiment 4 identified relationships between indicators and reproductive success including the finding that serum NEFA concentration 2 to 4 wk before AI is negatively correlated (P < 0.05) with PR to AI.

Crossbreeding is a common practice in poultry and swine breeding. Conversely, this mating system has not been widely adopted for breeding purposes in dairy cattle in temperate climates (except in New Zealand), mostly because of the superiority of Holsteins for milk yield, the economic relevance of this trait, the strong historical influence of purebred breeders and breed associations, and some biological aspects such as the low reproductive rate and the long generation interval of the cattle species. Recently, the interest in crossbreeding aspects has been growing among dairy producers, and this practice may be used to remove inbreeding depression accumulated in the major dairy breeds, to improve some economically important traits such as fertility, health, longevity, and calving ease, and to increase economic gains in countries where milk pricing systems have put a great emphasis on milk solids. It appears important to estimate the expected level of heterosis for traits of economic interest in dairy cattle in order to evaluate the profitability of crossbreeding. Objectives of this work were a) to estimate crossbreeding effects for milk yield traits and calving interval in dairy cows (Chapter 2), b) to investigate the influence of the environment on the expression of heterosis for milk yield traits, somatic cell score, and age at first calving in dairy cattle (Chapter 3), and c) to estimate the effect of different genotypes on age, live weight, price, and commercial value of purebred and crossbred calves sold for beef and veal production (Chapter 4). The thesis started with an introduction on crossbreeding in dairy cows (Chapter 1), followed by three contributions. Chapter 2 provided a study to assess crossbreeding effects for lactation milk, fat, and protein yield, and calving interval in dairy cows reared in Ireland. The analysis showed that breed effects for production traits were in favour of North American Holstein Friesian cows, while for calving interval were in favour of Friesian, Jersey, and Montbéliarde breeds. The highest heterosis estimates for milk yield traits were for crosses between North American Holstein Friesian and Jersey, with first generation cows giving 626 kg more milk, 25 kg more fat and 21 kg more protein than the average of the pure parental breeds. Regarding calving interval, the highest estimate was for crosses between North American Holstein Friesian and Montbéliarde, with first generation cows showing 10 d less calving interval than the average of the parental breeds. Estimates obtained in this study could be considered in the genetic evaluation model currently run in Ireland. Chapter 3 investigated the effect of the environmental level of production on the expression of heterosis for lactation milk, fat, protein, and fat plus protein yield, somatic cell score and age at first calving in primiparous Black and White dairy cows reared in The Netherlands. Holstein Friesian, Dutch Friesian and first generation crosses obtained from the mating of these strains were studied. The environments (low, medium, high) were defined on the basis of the herd production level. Holstein Friesian produced more than Dutch Friesian. First generation crosses showed comparable productions to Holstein Friesian, especially in the low environment. Estimates of heterosis for production traits ranged between 2.4% for milk yield in the high environment and 5.3% for fat yield in the low environment, with decreasing percentages observed for the traits when moving from the low to the high environment. Overall, heterosis for somatic cell score and age at first calving were moderate. Results emphasized that the highest non-additive genetic effects for yield traits were expressed in the most stressful environment, i.e. low level of production. Chapter 4 investigated the effect of four purebred genotypes (Brown Swiss and Holstein Friesian as dairy breeds, and Simmental and Alpine Grey as dual purpose breeds), and eight crossbred genotypes derived from mating of previous four dam breeds and two sire breeds (Limousin and Belgian Blue) on age (d), live weight (kg), price (Euro/kg), and market value (Euro/calf) of calves sold for veal and beef production during public auctions. Dual purpose purebred calves were heavier and presented higher price and market value than dairy purebreds (314 and 227 Euro/calf for Simmental and Alpine Grey, and 189 and 203 Euro/calf for Brown Swiss and Holstein Friesian, respectively). Crossbreeding with Limousin bulls increased live weight, price, and market value of calves from dairy and Alpine Grey cows, but had a small influence on price and market value of calves from Simmental cows. Crossbreeding with Belgian Blue bulls increased price and market value of calves much more than Limousin, particularly when used on Brown Swiss and Alpine Grey.
L’incrocio è il sistema riproduttivo di riferimento delle produzioni avicole e della maggior parte di quelle suinicole. In queste specie l’eterosi è un bonus utile e largamente sfruttato per migliorare la produttività e l’efficienza produttiva degli animali. Al contrario, nei climi temperati gli allevatori di vacche da latte tradizionalmente hanno escluso l’incrocio dalla gestione riproduttiva della loro mandria (produzione della rimonta). L’unica eccezione è rappresentata dalla Nuova Zelanda. I motivi alla base di questa esclusione sono la superiorità della razza Holstein per la produzione di latte, l’importanza economica assunta da questo carattere in molte realtà produttive, la forte influenza esercitata delle associazioni di razza a livello mondiale e alcune considerazioni di carattere biologico come la bassa efficienza riproduttiva e l’intervallo di generazione piuttosto lungo nella specie bovina. Tuttavia, il panorama zootecnico è in continua evoluzione e negli ultimi anni si è assistito ad un crescente interesse da parte degli allevatori nei confronti della possibilità di implementare l’incrocio in allevamento. Tale sistema riproduttivo può essere utilizzato per rimuovere gli effetti negativi della depressione da consanguineità che, nelle maggiori razze da latte, ha agito su diversi caratteri di interesse economico; l’accumulo di omozigosi e la conseguente depressione da consanguineità sono il frutto della forte pressione selettiva esercitata entro le razze pure. Inoltre, l’incrocio può costituire un valido strumento per il miglioramento dei caratteri funzionali a bassa ereditabilità tra cui la fertilità, il fitness, la longevità e la facilità di parto. Infine, può costituire un modo per migliorare la qualità del latte in termini di proteina e grasso in quelle realtà dove i costituenti del latte vengono premiati dai sistemi di pagamento vigenti. La valutazione della redditività di un programma di incrocio deve essere preceduta dalla stima dei livelli di eterosi per i caratteri economicamente rilevanti nelle bovine da latte. Gli obiettivi della presente tesi sono stati a) stimare gli effetti dell’incrocio per i caratteri produttivi e per l’interparto in vacche da latte (Capitolo 2), b) investigare l’influenza esercitata dall’ambiente sull’espressione dell’eterosi per caratteri produttivi, cellule somatiche ed età al primo parto in vacche da latte (Capitolo 3) e c) stimare l’effetto di diversi genotipi sull’età, il peso vivo, il prezzo ed il valore commerciale di vitelli puri e meticci venduti per la produzione di vitellone e vitello a carne bianca (Capitolo 4). La tesi inizia con un’introduzione sull’incrocio nel settore bovino da latte (Capitolo 1), seguita da tre contributi sperimentali. Nel Capitolo 2 sono stati stimati gli effetti dell’incrocio sulla produzione di latte, grasso e proteina, e sull’interparto in bovine da latte allevate in Irlanda. L’analisi ha evidenziato che gli effetti razza per i caratteri produttivi sono stati in favore della razza Holstein, mentre per l’interparto sono stati in favore delle razze Frisona, Jersey e Montbèliarde. Le stime più alte di eterosi per latte, grasso e proteina si sono avute nei meticci Holstein x Jersey: gli incroci di prima generazione hanno prodotto 626 kg di latte, 25 kg di grasso e 21 kg di proteina in più a lattazione rispetto alla media delle razze parentali pure. Per quanto concerne l’interparto, la stima più alta si è avuta nei meticci Holstein x Montbéliarde: gli incroci di prima generazione hanno evidenziato una contrazione di 10 giorni di interparto rispetto alla media delle razze parentali pure. Le stime ottenute in questo studio potrebbero essere considerate nel modello di valutazione genetica attualmente utilizzato in Irlanda. Nel Capitolo 3 è stato investigato l’effetto dell’ambiente (livello produttivo) sull’espressione dell’eterosi per la produzione di latte, grasso, proteina e materia utile (grasso più proteina), punteggio di cellule somatiche ed età al primo parto in bovine primipare Pezzate Nere allevate in Olanda. I genotipi presi in esame sono stati la Holstein, la Frisona Olandese e gli incroci di prima generazione tra queste due linee. Gli ambienti sono stati suddivisi in bassi, medi e alti sulla base del livello produttivo degli allevamenti. La Holstein ha manifestato produzioni più elevate rispetto a quelle della Frisona Olandese. Gli incroci di prima generazione hanno evidenziato produzioni simili a quelle della Holstein, soprattutto nell’ambiente basso. Le stime di eterosi sono risultate comprese tra il 2,4% per la produzione di latte nell’ambiente alto ed il 5,3% per la produzione di grasso nell’ambiente basso. Si sono osservate percentuali di eterosi decrescenti per latte, grasso, proteina e materia utile passando dall’ambiente basso a quello alto. Complessivamente, i livelli di eterosi per le cellule somatiche e l’età al primo parto sono risultati moderati. I risultati hanno messo in evidenza che gli effetti genetici non additivi per i caratteri legati alla produzione si sono espressi maggiormente nell’ambiente più stressante per tali caratteri, cioè quello basso. Nel Capitolo 4 è stato analizzato l’effetto del genotipo sull’età (giorni), il peso vivo (kg), il prezzo (Euro/kg) ed il valore commerciale (Euro/vitello) di vitelli venduti nel corso di aste pubbliche e destinati alla produzione di vitellone e vitello a carne bianca. I genotipi puri erano rappresentati da due razze da latte (Brown Swiss e Holstein) e da due razze a duplice attitudine (Simmental e Grigia Alpina), mentre i genotipi meticci erano di otto tipi diversi e sono stati ottenuti dall’accoppiamento delle precedenti quattro razze materne con due razze paterne (Limousin e Bianca Blu del Belgio). I vitelli puri figli di razze a duplice attitudine sono risultati più pesanti e hanno evidenziato un prezzo ed un valore commerciale più elevati rispetto a quelli dei vitelli puri di razze da latte (314 e 227 Euro/vitello rispettivamente per Simmental e Grigia Alpina e 189 e 203 Euro/vitello rispettivamente per Brown Swiss e Holstein). L’incrocio con tori Limousin ha incrementato il peso vivo, il prezzo ed il valore commerciale dei vitelli figli di vacche da latte e della Grigia Alpina, ma ha avuto una modesta influenza sui vitelli figli di vacche Simmental. L’incrocio con tori di razza Bianca Blu del Belgio ha incrementato prezzo e valore commerciale dei vitelli molto più di quanto non abbia fatto la razza Limousin, soprattutto quando la prima è stata utilizzata sulla Brown Swiss e sulla Grigia Alpina.

Variation in animal personality, in other words, behavioural responses consistent within individuals over time and/or across contexts, is predicted to be related to life-history traits, such as growth rate and investment in reproduction. How this translates into relationships between personality and milk production in dairy cows is however scarcely investigated and previous studies are showing contradicting results. To further investigate this relationship, individual consistencies in behaviour were related to milk production in two breeds of dairy cows (Swedish red and white cattle, SRB, and Holstein). Variation was found among the breeds in consistency of behaviours and both SRB and Holstein cows were highly consistent over time in stepping behaviour during milking and frequency of performed abnormal behaviours in home pen. Overall were Holstein cows consistent in more observed behaviours than SRB. Variation in neophobia and responses to social separation were more flexible, both among breeds and over time. Nevertheless, behaviour showed limited relationship with milk production. To conclude, the tests here carried out are useful in describing personality in cows; however, personality showed no relationship with milk production, encouraging future studies to explore this expected relationship further in other breeds and species.

Four visits were made to 50 dairy farms in England and Wales between February 2003 and February 2004 and a further three visits to 42 of these farms between February 2005 and February 2006. At each visit the locomotion of all cows was scored (15,597 cows, 34,643 measures). Multivariable regression analyses were preformed to identify risk factors associated with increased lameness (poor locomotion). Factors associated with mean herd poor locomotion were dry cows kept in straw yards compared with cubicle houses, pregnant heifers kept with milking cows compared with dry cows in winter, passage way widths <3m compared with 2:,3m, a kerb height of ~15cm compared with >15cm, routine trimming of claws ofall cows by a claw trimmer or by- the farmer compared with no routine claw trimming, feeding maize silage to milking cows compared with other forage types, and the use of automatic scrapers compared with tractor scrapers in the cubicle house. Farmers recorded the lesions they observed while treating lame cows. Sole ulcer, white line disease and digital dermatitis were the three most frequently recorded lesions. The occurrence of sole ulcer, white line disease or digital dermatitis compared with having no lesion was used as the outcome variable in three multilevel binomial logistic regression models with month from calving nested within cow nested within farm. Risk factors associated with increased risk of sole ulcer were being housed on sparse bedding for four months or more, having grooved concrete floors on ~e farm, large herd sizes and parity numbers of four and above. Risk factors associated with increased white line disease were grooved concrete floors increasing parity number. Risk factors associated with increased digital dermatitis were grooved concrete floors and large herd sizes. A large clinical trial was used to assess the effect of intervening on known risk factors associated with lameness. Farmers in the treatment group received farm specific recommendations grouped under five targets areas which reflected the hypothesised aetiologies of sole ulcer, white line disease and digital dermatitis. There were small reductions in locomotion score and sole ulcer rate on treatment farms compared with control. These suggested that the hypotheses that reduced standing time and encouraged increased lying time through improved cow comfort may reduce sole ulcer were, at least in part, correct. There was no clear effect of treatment on the rate white line disease and digital dermatitis. It is likely that more than one of the following factors explain the lack of significant results from these initial investigations; poor recognition oflameness by farmers, insufficient uptake of recommendations, predisposition to lameness from previous lameness event and insufficiently specific lesion definitions.

In commercial dairy cattle farming, stressful disease conditions, such as high somatic cell count (SCC), poor body condition score (BCS) or lameness, are associated with subfertility. The objective of this thesis is to identify key areas in the reproductive cycle associated with each condition which contribute to this subfertility. Cows 30-80 days post partum from two commercial dairy farms were scored for SCC, BCS and lameness over a 5 week period prior to the implementation of an oestrous synchronization programme. Blood and milk sampling, trans-rectal ultrasonography and oestrus behaviour monitoring were conducted. Follicular development from emergence to deviation was unaffected as all cows produced a dominant follicle, which continued to grow beyond lOmm. In the following period, mean follicular growth, maximum follicular diameter and time to ovulation were not influenced by any of the 3 conditions (p> 0.05). In the animals that ovulated (irrespective of clinical status), follicles grew faster and achieved a greater diameter than in the animals that failed to ovulate (p< 0.05). Fewer lame animals ovulated compared to healthy animals (p< 0.05) and fewer high SCC animals with concurrent lameness ovulated than cows with only high SCC (p< 0.05) In cows with high SCC, progesterone concentrations prior to PG injection, over the peri-ovulatory period, on Days 5 and 7 or during the mid luteal phase after ovulation were unaffected, as was mean oestradiol concentration prior to ovulation. In the cows that ovulated, the dominant follicle grew at the same rate and ovulated at a similar size and at the same time regardless of high SCC, lameness or both. High SCC cows tended to (p< 0.07) and lame cows did express an oestrus of lower intensity and had a lower maximum intensity score than healthy animals (p< 0.05). High SCC cows started displaying oestrus signs and stood to be mounted (STBM) later than their healthy counterparts (p< 0.05) while lame animals displayed oestrus and STBM earlier than non lame cows (p< 0.05).

The objectives of this study were to characterize the hematological and productive pattern during the peripartum in cows with and without anemia, as well as to evaluate the erythrogram in animals that presented metritis puerperal acute (MPA), lameness, acetonemia, increased non-esterified fatty acids (NEFA) and cows with different categorization of body condition score (BCS). In study 1, 50 Holstein cows (29 multiparous and 21 primiparous) were used. Blood samples and physical examination were performed at 13 different times: 18 ± 3, 12 ± 2, 5 ± 1, and 2 ± 1 before calving, and 7, 14, 21, 30, 45 and 60 days postpartum. Erythrogram evaluations were performed, and red blood cell count (RBC), hemoglobin concentration, packed cell volum (PCV), and absolute hematimetric values of mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), mean corpuscular hemoglobin, RDW, serum concentrations of iron, betahydroxybutyrate (BHBA), AGNE and total bilirubin (TBIL) were determined for the biochemical analyzes. Anemia was classified according to hemoglobin values <7 g / dL and globular volume <24%. The prevalence of anemia was higher in the period 60 days postpartum affecting 18.3% of the animals, the pattern of anemia presented was normocytic, normochromic, regenerative. RBC, PCV and hemoglobin were lower (P <0.05) for animals with anemia. While the animals with MPA and lameness the value of the erythrogram was very similar throughout the postpartum period. No difference was observed between the groups according to the values of NEFA, BCS and loss of BCS during the periods performed in the postpartum period. In conclusion the anemic animals presented the values of the physical examination according to the physiological limits, the anemia did not cause productive losses in the affected animals. It was not evidenced that animals with MPA and claudicants presented a greater reduction of blood crass, excluding the occurrence of inflammatory anemia, and although the prevalence of anemia increased during postpartum, it was not possible to characterize the main cause of the reduction of hematological values between the categorizations. In the second study, blood was sampled from 336 animals (252 multiparous and 84 primiparous) between 21 and 30 days in lactation (DEL) on 7 farms in the State of São Paulo with the objective of characterizing the prevalence of anemia in dairy cows, prevalence of anemia in different categorizations such as: lactation number, BCS at the time of collection, dystocia, retention of fetal membranes, mastitis, digestive problem, lameness and acetonemia, , as well as the analysis erythrogram, biochemical profile, BCS, and milk production among animals with and without anemia. In conclusion, the prevalence of anemia was low (16.3%) and no association with the categorizations performed in this study, it was not possible to characterize the cause of anemia through biochemical analysis.
Os objetivos deste estudo foi caracterizar o padrão hematológico e produtivo durante o periparto em vacas com e sem anemia, assim como avaliar o eritrograma em animais que apresentaram metrite puerperal aguda (MPA), claudicação, acetonemia, valores de ácidos graxos não esterificados aumentados (AGNE) e vacas com diferentes categorizações de escore de condição corporal (ECC). No estudo 1, foram utilizadas 50 vacas Holandesas (29 multíparas e 21 primíparas), foram realizadas colheitas sanguíneas e exame físicos em 13 momentos diferentes: 18 ± 3, 12 ± 2, 5 ± 1, e 2 ± 1 antes do parto, parto, e 7, 14, 21, 30, 45 e 60 dias após o parto. Foram realizadas avaliações do eritrograma sendo mensurado a contagem de hemácias (RBC), concentração de hemoglobina, volume globular, além dos valores hematimétricos absolutos do volume corpuscular médio (VCM), concentração hemoglobínica corpuscular média (CHCM), hemoglobina corpuscular média (HCM) e RDW, para as análises bioquímicas foram determinadas a concentração sérica de ferro, betahidróxidobutirato (BHBA), AGNE e bilirrubina total (TBIL). Anemia foi classificada de acordo com os valores de hemoglobina < 7 g/dL e o volume globular < 24 %. A prevalência de anemia foi maior no período 60 dias após o parto afetando 18.3% dos animais, o padrão da anemia apresentado foi normocítica, normocrômica, regenerativa. Os valores das contagens de hemácias, volume globular e hemoglobina foram menores (P < 0.05) para os animais com anemia. Enquanto os animais com MPA e com claudicação, o valor do eritrograma foi muito semelhante ao longo do pós-parto. Não foi observado diferença entre os grupos de acordo com os valores de AGNE, ECC e perda de ECC durante as coletas realizadas no pós-parto. Em conclusão os animais anêmicos apresentaram os valores do exame físico de acordo com os limites fisiológicos, a anemia não provocou perdas produtivas nos animais afetados. Não foi evidenciado que animais com MPA e claudicantes apresentassem maior redução da crase sanguínea, excluindo a ocorrência de anemia inflamatória, sendo que embora a prevalência de anemia aumentasse durante o pós-parto não foi possível caracterizar a causa principal da redução dos valores hematológicos entre as categorizações realizadas. No estudo 2, foram realizadas coletas sanguíneas em 336 animais (252 multíparas e 84 primíparas) entre 21 e 30 dias em lactação (DEL) em 7 fazendas no Estado de São Paulo com objetivo de caracterizar a prevalência de anemia nos animais, prevalência de anemia em diferentes categorizações realizadas como: distocia, retenção dos anexos fetais, mastite, problema digestivo, claudicação, acetonemia, ECC no momento da coleta e número de parto, assim como a análise do eritrograma, bioquímico e ECC e produção de leite entre os animais com e sem anemia. Em conclusão a prevalência de anemia foi baixa prevalência (16.3 %) e nenhuma associação com as categorizações realizadas nesse estudo, adicionalmente não foi possível caracterizar por meio de análises bioquímicas a causa da anemia.

Several indicators of animal welfare were measured to determine the impact of relocation on lactating dairy cows. In experiment one, locomotion was scored on a 4-point scale where 1 = normal and 4 = lame. Cleanliness was scored on a 4-point scale where 1 = little or no manure visible and 4 = heavy plaques of manure on 3 body regions: udder, lower leg, and flank/upper leg. In experiment two, milking parlor behaviors observed were cow reactivity (REACT), latency to enter the parlor (LAT), and plasma cortisol (CORT). REACT was evaluated on a numeric scale (0 = ideal milker to 3 = steps and kicks frequently) to define behavior during udder preparation, claw fitting, and milking. LAT was the time necessary for each cow to enter the milking parlor. In these studies, the effects of treatment or breed on MY, lameness, parlor behaviors, stress, and cow cleanliness were monitored. In experiment one, cows with access to a rubber mat in front of the feed bunk had lower locomotion scores and cleaner lower legs. There were no breed effects on locomotion, but Jerseys had cleaner lower legs than Holsteins. The effect of the new facility on locomotion occurred gradually. Cows with higher locomotion scores had decreased milk production, but the results were not significant. In experiment two, relocation caused an increase in plasma cortisol and LAT. Milk yield decreased the p.m. on the day of relocation, but overall milk yield was not affected. Jerseys had lower plasma cortisol levels and latency to enter the parlor, but had a greater decline in p.m. milk yield the day of relocation. In conclusion, alternative flooring may alleviate some locomotion problems caused by relocation to a new facility. Additionally, moving to a new facility may have an effect on behavior and stress, but these effects are short-lived and effects on overall milk production minimal.
Master of Science

The objective of this thesis was to investigate housing and management risk factors associated with the prevalence of hock injuries in freestall herds (n = 76) in two areas of intensive dairy production, Northeastern US (NE-US) and California (CA). One group of high-production multiparous cows (n = 38) was monitored for hock injuries on each farm and data on management, facility and stall design were collected. Risk factors associated with the overall proportion of cows having injuries or severe injuries at the univariable level were submitted to multivariable general linear models. In NE-US, overall hock injuries increased with the percentage of stalls with fecal contamination (OR = 1.26; CI = 1.02 to 1.54, for a 10% increase), and with the use of sawdust bedding (OR = 3.47; CI = 1.14 to 10.62), and decreased with deep bedding (OR = 0.05; CI = 0.02 to 0.14), sand bedding (OR = 0.06; CI = 0.02 to 0.15), bedding DM ≥ 83.9% (OR = 0.08; CI = 0.03 to 0.20), and access to pasture during the dry period (OR = 0.17; CI = 0.05 to 0.53). In the multivariable model, only the presence of deep bedding remained significant. Severe hock injuries increased with the use of automatic scrapers (OR = 2.29; CI = 1.11 to 4.71) and the percentage of stalls with fecal contamination (OR = 1.14; CI = 1.00 to 1.31, for a 10% increase), and decreased with sand bedding (OR = 0.22; CI = 0.10 to 0.49), deep bedding (OR = 0.24; CI = 0.11 to 0.52), bedding DM ≥ 83.9% (OR = 0.28; CI = 0.14 to 0.58), and access to pasture during the dry period (OR = 0.42; CI = 0.18 to 0.97). The multivariable model included the use of automatic scrapers and deep bedding. In CA, stall stocking density (OR = 1.41; CI = 1.00 to 2.01, for a 10% increase) and bedding concavity (OR = 1.08; CI = 1.01 to 1.16, for a 2.5-cm decrease) were associated with an increase of hock injuries. In general, deep-bedded and well-maintained stalls significantly reduced the risk of hock injuries.

PERFORMANCE OF DAIRY COWS FED SOYBEAN SILAGE The objective of this research was to determine the feeding values of forage soybean (cv. Kodiak, full pod stage) silage to lactating dairy cows. Two diets with a 50:50 forage:concentrate ratio were formulated to meet nutrient requirements of dairy cows in early lactation. Soybean silage (SS) or a fourth cut alfalfa silage (AS) comprised 72% of the forage in each diet, with corn silage comprising the remaining 28%. Twenty Holsteins cows in early lactation were used in a Switchback design to determine the effects of dietary treatments on milk yield and milk composition. Four lactating cows fitted with ruminal cannulae were used in a Switchback design to determine effects of dietary treatments on ruminal fermentation and total tract nutrient digestibilities. Cows fed SS consumed less (P < 0.05) feed and produced less (P < 0.05) milk than cows fed AS. However, energy-corrected milk and milk efficiency were similar for both dietary treatments. Milk fat percentage and milk urea nitrogen were higher (P < 0.05) in milk of cows fed SS than in milk of cows fed AS. However, milk protein and lactose concentrations were similar for both dietary treatments. Ruminal pH and NH3 N were lower (P < 0.05) in cows fed AS than in cows fed SS. However, total and molar proportions of volatile fatty acids were not influenced by dietary treatments. Total tract digestibility of DM, OM, CP, NDF, and GE were similar for dietary treatments. Results of the present study revealed the potential of forage soybean silage as a forage source of dairy cows. More research is needed to determine the optimum stage of development at harvest to improve the nutritive value of soybean silage for dairy cows.
ÉVALUATION DE LA PERFORMANCE DE VACHES LAITIÈRES ALIMENTÉES AVEC DE L'ENSILAGE DU SOYA Le but de cette recherche était de déterminer la valeur nutritive de l'ensilage de soya (cv. Kodiak, Gousses remplies) lorsque servit à des vaches laitières en lactation. Deux diètes avec un ratio fourrage : concentré 50 : 50 ont été formulées afin de rencontrer les besoins nutritifs de vaches laitières en début de lactation. De l'ensilage de soya (ES) ou de l'ensilage de quatrième coupe de luzerne (EL) représentait 72% du fourrage dans chacune de ces diètes, alors que le 28% résiduel était comblé par de l'ensilage de mais. Vingt vaches de race Holstein en début de lactation ont été utilisées sous un plan de permutation de traitements afin de déterminer les effets des deux différentes diètes sur la production et la composition du lait. Toujours à l'aide d'un plan de permutation de traitements, quatre vaches munies d'une fistule ruminale permanente ont été utilisées afin de déterminer les effets des deux différentes diètes sur la fermentation ruminale et la digestibilité totale des nutriments. Les vaches recevant une diète ES avaient une consommation volontaire moindre (P < 0.05) et produisaient moins de lait (P < 0.05) que celles recevant une diète EL. Toutefois, les valeurs du lait corrigé et d'efficacité laitière étaient comparables pour les deux diètes. Le pourcentage de gras du lait et l'urée du lait des vaches recevant une diète ES étaient plus élevés (P < 0.05) que ceux des vaches recevant une diète EL. Toutefois, les pourcentages de protéine et de lactose du lait étaient similaires pour les deux diètes. Le pH et le NH3 N au niveau du rumen étaient plus bas (P < 0.05) pour les vaches recevant une diète EL que celles recevant une diète ES. Le type de diète n'a pas eu d'influence sur les proportions totales et molaires des acides gras volatils. Des valeurs semblables ont été observées en ce qui concerne$

Automatic sampling and analysis of milk composition for on-line metabolic profiling has been proposed as a means of monitoring individual cows to detect and correct problems in nutritional management. Acetone, urea, fat, protein and citrate in milk were investigated independently and jointly as potential indicators for monitoring the dairy cow. A series of experiments and milk analysis were conducted to investigate sources of variation within and between cows, nutritional effects on milk composition and whether dietary changes could be detected through changes in milk composition. Novel methods for on-line acetone and urea analysis were also tested. Significant diurnal variation was found in fat, acetone and urea but not in citrate or protein. Acetone and citrate were the most variable constituents; day-to-day variation was 64.3% of mean acetone and 16.4% of mean citrate. Between cow variation was significant in all milk constituents monitored, in terms of means and normal concentration ranges, highlighting the need for individual cow management. Individual variation could be determined by establishing normal ranges of milk constituents for each cow, so that deviations from normal can be detected. Dietary changes at the group and individual cow levels were not detectable and individual responses to dietary changes were unpredictable. Changing the starch to fibre ratio in the diet had no effect on milk acetone and effects on urea, fat and protein were only significant when dietary changes were extreme. Energy output, in terms of FCM, was more closely correlated with fat: protein ratio (R2=0.3) than with acetone (R2=0.006), so the use of acetone as an indicator of metabolic status is inconclusive. Further research on a larger scale is needed to determine whether on-line monitoring will be feasible for nutritional management and economically justified in practice.

Many concerns over the welfare of dairy cattle occur during the time around parturition. As cows transition from a pregnant to a lactating state, they are at high risk of disease and other painful conditions. In most intensive housing systems, these ‘transition’ cows are also kept in environments designed for the ease of management, with little consideration given to the expression of natural behaviours. This thesis addresses two main themes that are currently missing from the transition cow literature: 1) using knowledge of behaviour to improve management and housing practices, and 2) using behaviour as an indicator of poor health. Chapters 3, 4 and 5 address the first theme, and provide evidence that common management practices that disturb cows during parturition may interfere with calving; cows moved from a group pen into an individual pen during a late stage of labour spent more time standing in the hour before calving and experienced prolonged stage II labour compared to those moved earlier. Next, two preference studies were used to determine the type of environments that cows prefer during parturition. Results suggest that cows prefer to be in an undisturbed, secluded environment during labour and calving. To address the second theme, Chapter 2 describes the growing evidence in the human and laboratory animal literature that social behaviour can be useful as both an indicator of illness, as well as an early predictor of disease. Yet, there is little research to date making this link in farm animals. The remaining chapters describe studies that used behaviour to identify cows with three major health problems: infectious disease, dystocia and lameness. Cows with infectious diseases ate less, spent more time lying and secluded themselves from a nearby group pen, all common sickness behaviours in other species. Feeding, social and standing behaviours were also found to predict cows at-risk for dystocia and lameness well before diagnosis. Collectively, these results provide evidence that a better understanding of transition cow behaviour can be useful to both improve housing and management, as well as identify cows at-risk for poor health.

Thesis (PhD)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: In this study, five trials were conducted to examine in vitro and in vivo degradation, excretion and absorption parameters of melamine (MEL) in dairy cows that have not been studied before or where limited information is available. The first two trials were in vitro studies conducted to determine the extent of MEL degradation in rumen liquor and the effects of MEL on ruminal ammonia (NH3) and volatile fatty acid (VFA) concentrations. For both trials, rumen liquor was collected from ruminally cannulated lactating Holstein cows. For the first and second trial, rumen liquor was collected from three and two cows, respectively. For both trials, Erlenmeyer flasks contained 1 g substrate and 100 mL incubation medium consisting of 20 mL rumen liquor and 80 mL reduced buffer solution. In the first trial, each flask contained 100 mg of MEL, resulting in an initial MEL concentration of 1000 mg/L. The flasks were incubated at 39° C for 0 (Control), 6, 24 or 48 hours under strictly anaerobic conditions. In all the trials, MEL concentrations were determined by LC/MSMS. MEL degradation was low after 6 and 24 h of incubation (3.2 and 5.5%, respectively) and increased to 13.6% after 48 h of incubation. In the second trial where VFA and NH3 concentrations were determined, the flasks contained either 0 (Control), 0.2 (T1) or 0.4 mg (T2) of MEL. The flasks were incubated for 6, 24 or 48 h. Treatment had no effect on individual or total VFA concentrations or NH3 concentrations at 6 and 48 h. At 24 h, T2 resulted in an inexplicable higher NH3 concentration. This study showed that the addition of melamine would not result increased rumen NH3 concentrations in vitro. Melamine would also not affect the production of different VFA’s. Therefore, it was concluded that the rumen micro-organisms present in rumen liquor would be unable to utilize MEL as a source of nitrogen and that the microbial production of VFA’s remains unaffected by the presence of MEL. In the third trial, MEL excretion in lactating cows was determined. Five cows were randomly allocated to treatments according to a 5 x 5 Latin square design. Cows received the treatment diets for 7 d followed by 8 d of MEL withdrawal during each of the five periods. The experimental treatments were formulated to provide a daily MEL intake of 0 (M0), 500 (M1), 1000 (M2), 5000 (M3) or 10000 mg (M4) via 15 kg of dairy concentrate pellets. Calculations based on the work of Newton & Utley (1978) suggested that a melamine intake of 0.16 g/kg of live weight would not result in detrimental health effects of ruminant animals. Therefore, a 600 kg lactating dairy cow should not be at risk when consuming 100 g of melamine. In this trial, the highest melamine treatment (M4 = 10 g/d) included a 10-fold safety factor from the suggested safe amount from the work of Newton & Utley (1978) and should not pose a health risk to the cows. Treatments had no effect on DMI, milk yield or milk composition. MEL was detected in the milk 8 h after initial MEL ingestion, increased rapidly and peaked on d 3 and was undetectable after 8 d. Treatments had no effect on MEL excretion efficiencies which ranged from 1.5 to 2.1%. The mean apparent digestibility of MEL was 78%. Mean faecal and urinary MEL excretions were 22 and 54 % of ingested MEL, respectively. Higher milk, urine and faecal MEL concentrations were observed with higher levels of dietary MEL. It was concluded that MEL appeared in the milk soon after first ingestion and a withdrawal period of 8 d was required for all milk, faecal and urine samples to reach undetectable levels of MEL. Urine and faeces were the primary routes for MEL excretion. The fourth trial was conducted to determine MEL absorption by the mammary gland in lactating dairy cows through arterio-venous (A-V) difference. Five cows received 10 g of MEL/d for three consecutive days. Day 3 of the trial was selected for commencement of blood sampling as previous studies (Cruywagen et al., 2009; Shen et al., 2010; Sun et al., 2011) reported the milk melamine concentration to reach a peak on d 3 of continuous melamine consumption by dairy cows. Early on d 3, catheters were inserted into the caudal superficial epigastric vein (milk vein) and caudal auricular artery. The blood sampling period commenced after residual milk removal from the udder following oxytocin administration. Blood from both locations were collected hourly for 9 hours. Following the final blood collection, oxytocin was administered again, catheters were carefully removed and cows were milked immediately thereafter. All blood samples were centrifuged and the decanted plasma was analysed for MEL, as well as for amino acid contents to calculate mammary blood flow. The positive MEL flux (calculated from A-V difference) confirmed net absorption of MEL into the mammary gland with an efficiency of absorption of 0.29%. Melamine excretion into milk was 5.63 mg/h. The mean plasma and milk MEL concentrations were 5.2 and 3.9 mg/kg, respectively. Melamine excretion efficiency to milk, expressed as percentage of the ingested amount, was 1.47%. It was concluded that melamine ingested by cows will result in net MEL absorption by the mammary gland, but that the absorption efficiency is low. The final trial of the study aimed to determine the effects that fermentation processes during the manufacturing of cheese, yoghurt and kefir would have on their MEL content if these products were made from MEL contaminated milk. Another objective was to determine if MEL in cheese would be degraded during the curing process. Cheese, yoghurt and kefir were made from milk with a MEL content of 6.77 mg/kg. The cheese was then cured for 2 wk at 6° C. The MEL contents of the yoghurt and kefir were 6.76 and 6.78 mg/kg, respectively, indicating that the different fermentation processes used in yoghurt and kefir production had no effect on their MEL content and that MEL was not degraded during the short fermentation periods. The percentage of milk MEL partitioned to whey and cheese were 97.4 and 6.5 %, respectively. It was concluded that the different fermentation processes involved during the manufacturing of yoghurt and kefir from MEL tainted milk did not decrease the MEL concentration. The milk MEL was predominantly partitioned to whey, with little MEL transferred to cheese. It was also concluded that MEL was not degraded in cheese during a 2-wk curing period. It was finally concluded that dietary MEL is readily absorbed by dairy cows and mainly excreted via the urine. The mammary gland has a low affinity for MEL absorption and approximately 2% of ingested MEL is excreted in the milk. When cheese is made from MEL tainted milk, the majority of MEL will concentrate in the whey fraction and only 6.5% will be present in the cheese.
AFRIKAANSE OPSOMMING: Vyf proewe is gedoen om in vitro- en in vivo-degradering, uitskeiding en absorpsie parameters van melamien (MEL) na te gaan waaroor daar min of geen inligting bekend was nie. Die eerste twee proewe was in vitro-studies, uitgevoer om die mate van MEL degradeerbaarheid in rumenvloeistof na te gaan, asook die invloed van MEL op rumen-NH3 en vlugtige vetsuur (VVS)-konsentrasies. Vir beide proewe is rumenvloeistof van lakterende, rumengekannuleerde Holsteinkoeie verkry. Vir die eerste en tweede in vitro-studies, was rumenvloeistof verkry vanaf drie en twee koeie, onderskeidelik. In albei proewe is 1 g substraat in Erlen-meyerflessies afgeweeg en 100 mL inkubasiemedium bygevoeg wat uit 20 mL rumenvloeistof en 80 mL van ‘n buffermedium bestaan het. In die eerste proef is 100 mg MEL by die substraat gevoeg, sodat die aanvanklike MEL konsentrasie in die flessies 1000 mg/L was. Die flessies is by 39° C geïnkubeer vir 0 (Kontrole), 6, 24 of 48 ure, onder streng anaerobiese kondisies. Met die beïndiging van die inkubasieperiode is 100 mL van ‘n 0.2 M perchloorsuuroplossing bygevoeg om enige melamien wat nie gedegradeer was nie, op te los. In al die proewe is melamienbepalings by wyse van LC/MSMS gedoen. Melamiendegradering was laag na 6 en 24 h inkubasie (3.2 en 5.5%, respektiewelik) en teen 48 h inkubasie het dit toegeneem tot 13.6%. In die tweede proef het die flessies 0 (Kontrole), 0.2 (T1) of 0.4 mg (T2) melamien bevat. Behandeling het geen invloed op individuele of totale VVS-konsentrasies by enige van die inkubasietye gehad nie en ook nie op NH3-konsentrasies by 6 en 48 h nie. Om een of ander onverklaarbare rede het die T2-behandeling gelei tot hoër NH3-konsentrasies by 24 h. Die gevolgtrekking is gemaak dat die byvoeging van MEL geen effek op rumen NH3-konsentrasies het nie en dat die mikroorganismes in die rumen nie daartoe in staat sal wees om MEL as ‘n stikstof-bron sal kan benut nie. In die derde proef is die uitskeiding van MEL in melkkoeie ondersoek. Vyf lakterende Holsteinkoeie is ewekansig aan vyf behandelings toegeken in ‘n 5 x 5 Latynsevierkantontwerp. Gedurende elke periode het koeie die behandelings vir 7 d ontvang, gevolg deur ‘n 8 d MEL-onttrekkingsperiode. Die eksperimentele diëte is geformuleer om ‘n daaglikse MEL-inname van 0 (M0), 500 (M1), 1000 (M2), 5000 (M3) of 10000 mg (M4) per koei/dag te verseker, toegedien via 15 kg/d van ‘n suiwelkonsentraat in pilvorm. Berekeninge gebasseer op die werk van Newton & Utley (1978) stel voor dat ‘n MEL inname van 0.16 g/kg lewende massa, geen negatiewe effek op herkouers se gesondheid sal hê nie. Dus, ‘n koei wat 600 kg weeg, sal geen skade lei deur die inname van 100 g MEL nie. In hierdie proef was die hoogste MEL behandeling (M4 = 10g/d) tien keer laer as die voorgestelde veiligheidsvlak van Newton & Utley (1978). Behandeling het geen invloed op DMI, melkopbrengs of melksamestelling gehad nie. Melamien is so gou as 8 h na eerste inname in die melk waargeneem, waarna die konsentrasie vinnig toegeneem het en ‘n piek na 3 d bereik het. Behandeling het geen invloed op die uitskeidingsdoeltreffendheid van melamien in melk gehad nie en waardes het gewissel van 1.5 tot 2.1%. Die gemiddelde skynbare verteerbaarheid van MEL was 78%. Die gemiddelde mis- en uriene-MEL-konsentrasies was 22 en 54%, onderskeidelik. Hoër melk-, mis- en uriene-MEL-konsentrasies is waargeneem namate die MEL-inhoud van die diëte gestyg het. Die gevolgtrekking is gemaak dat MEL spoedig na eerste inname in die melk verskyn en dat ‘n onttrekkingsperiode van 8 d benodig word voordat melk-, mis- en uriene-MEL onwaarneembare vlakke bereik. Uriene en mis is die primêre uitskeidingsroetes van ingenome MEL. Die vierde proef is onderneem om MEL-absorpsie in die melkklier met behulp van arterio-veneuse (A-V) verskille te ondersoek. Vyf koeie het elk 10 g MEL/d vir drie agtereen-volgende dae ontvang. Dag 3 van die proef is gekies vir bloedkolleksies aangesien vorige studies (Cruywagen et al., 2009; Shen et al., 2010; Sun et al., 2011) gewys het dat melk MEL op dag 3 van MEL inname, piek konsentrasies beryk. Vroeg gedurende die oggend van d 3 is kateters in die kaudale oppervlakkige epigastriese aar (melkaar) en die kaudale aurikulêre slagaar geplaas. Die bloedtrekkingsperiode het ‘n aanvang geneem direk nadat die koeie volledig uitgemelk is na toediening van oksitosien om te verseker dat soveel as moontlik residuele melk verwyder word. Monsters van veneuse-, sowel as arteriële bloed, is 9-uurliks geneem. Na die finale bloedtrekking is oksitosien weer toegedien, die kateters is versigtig verwyder en die koeie is direk daarna weer gemelk. Al die bloedmonsters is gesentrifugeer en plasmamonsters is ontleed vir MEL, asook vir aminosuursamestelling ten einde bloedtoevoer na die uier te bereken. Die positiewe fluks (bereken van A-V verskil) het bevestig dat netto MEL absorpsie in die melkklier plaasvind, met ‘n doeltreffendheid van 0.29%. Melamienuitskeiding in die melk was teen ‘n tempo van 5.63 mg/h. Die gemiddelde plasma- en melk-MEL konsentrasies was 5.2 en 3.9 mg/kg, onderskeidelik. Die uitskeidingsdoeltreffendheid van MEL na melk, uitgedruk as persentasie van ingenome MEL, was 1.47%. Die gevolgtrekking is gemaak dat MEL wat deur koeie ingeneem word, tot netto MEL-absorpsie in die melkklier sal lei, maar dat die absorpsiedoeltreffendheid baie laag is. In die finale proef is daar gepoog om die invloed van fermentasieprosesse gedurende die vervaardiging van kaas, joghurt en kefir op die produkte se melamieninhoud na te gaan indien die produkte van melamienbevattende melk gemaak sou word. ‘n Tweede doel van hierdie proef was om te bepaal of MEL in kaas gedegradeer kan word tydens rypwording. Kaas, joghurt en kefir is gemaak van melk wat ‘n MEL-inhoud van 6.77 mg/kg gehad het. Die kaas is vervolgens vir twee weke by 6° C rypgemaak. Die MEL-inhoud van die joghurt en kefir was 6.76 en 6.78 mg/kg, onderskeidelik, wat daarop dui dat die onderskeie fermentasieprosesse wat tydens die bereiding van joghurt en kefir plaasvind, geen invloed op hul MEL-inhoud gehad het nie en dat MEL nie gedurende hierdie kort fermentasieperiodes gedegradeer is nie. Die persentasie MEL na wei en kaas versprei was 97.4 en 6.5%, onderskeidelik. Die gevolgtrekking is gemaak dat die verskillende fermentasieprosesse betrokke tydens die vervaardiging van joghurt en kefir wat van melamienbesmette melk gemaak word, nie die MEL-konsentrasie verlaag het nie. Tydens die vervaardiging van kaas, word die MEL hoofsaaklik na die weikomponent versprei en baie min na kaas. Melamien word ook nie in kaas afgebreek gedurende ‘n verouderingsproses van twee weke nie. Die finale gevolgtrekkings is gemaak dat MEL maklik deur melkkoeie geabsorbeer word en dat die hoof uitskeidingsroete via urine is. Die uier het ‘n lae affiniteit vir MEL absorpsie en ongeveer 2% van ingenome MEL is in die melk uitgeskei. Wanneer kaas van MEL besmette melk gemaak word, sal die meerderheid van die MEL in die weifraksie konsentreer, met slegs 6.5% teenwoordig in die kaas.
The Hennie Steenberg Trust Fund, the Ernst and Ethel Erickson Trust and the National Research Foundation (NRF) for their financial support

Doctor of Philosophy
Department of Animal Sciences and Industry
Barry J. Bradford
The transition period in dairy cows is characterized by dramatic increases in nutrient requirements for lactation and substantial metabolic stress. The disturbed metabolic balance, coupled with suppressed immune function, contributes to markedly elevated incidence of health disorders. Several lines of evidence suggest that increased inflammation is common during the transition period. Unlike the classical inflammation associated with acute infection, the postpartum inflammatory state is low-grade and often of metabolic origin. This metabolic inflammation plays a key role in numerous disorders; an improved understanding of inflammatory pathways in transition cows may improve our ability to predict and prevent disorders. To mimic metabolic inflammation, in Experiment 1, we administered low amounts of recombinant bovine tumor necrosis factor-α (rbTNFα), a pro-inflammatory cytokine, to early lactation cows, and evaluated whether rbTNFα affects milk production, metabolism, and health. We found that rbTNFα administration increased systemic inflammation, decreased feed intake and milk yield, and increased incidence of disorders. Conversely, preventing excessive inflammation has the potential to improve productivity and health of dairy cows. To identify nutritional strategies that could enhance metabolism and immunity, we evaluated the efficacy of several feed additives. In Experiment 2, we evaluated effects of chromium propionate, rumen-protected lysine and methionine, or both on metabolism and immunity in lactating dairy cows, and found that supplementation of these nutrients may enhance neutrophil function. In Experiment 3, we determined whether supplementation of yeast product to transition cows could enhance production, metabolism, and immunity, and found that yeast product modulated feeding behavior, metabolism, immunity, and uterine inflammation. Overall, a greater understanding of the role of metabolic inflammation in the transition period and the nutritional strategies that could modulate these signals may improve the production and health of dairy cows.

Master of Science
Animal Sciences and Industry
Jeffrey S. Stevenson
Using an activity monitoring system (AMS) equipped with an accelerometer, 2 experiments were conducted to test the hypotheses that: (1) altering progesterone before inducing luteolysis or (2) exposing cows to estradiol cypionate (ECP) or testosterone propionate (TP) after luteolysis would increase occurrence and intensity of estrus. In experiment 1, cows (n = 154) were fitted with an AMS collar and a pressure-sensitive, rump-mounted device (HW) and assigned to 3 treatments: 1) CL only; 2) no CL + progesterone insert (CIDR); or 3) CL + 2 CIDR to achieve different concentrations of progesterone. Progesterone concentration 24 through 120 h post-treatment was greatest (P < 0.01) in CL + 2 CIDR, followed by CL, and no CL + CIDR cows. Estrus occurred 11 to 12 h earlier (P < 0.01) in no CL + CIDR compared with CL-bearing cows. Estrus intensity was greater (P < 0.05) after CL + 2 CIDR than CL only cows. The AMS and HW determined 68 and 62% of qualifying cows to be in estrus (estrus was defined: follicle ≥ 10 mm at PGF[subscript 2α] and progesterone ≤ 0.5 ng/mL 72 h later), respectively. In experiment 2, cows (n = 203) were equipped with an AMS and a friction-activated, rump-mounted patch (Estrotect patch; ET) and assigned to receive 1 mg ECP, 2 mg TP, or control 24 h after PGF[subscript 2α]. Estradiol 24 h post treatment was greater (P < 0.01) in ECP compared with controls. Estrus expression detected by ET in all cows tended (P = 0.10) to be greater for ECP compared with controls. More (P < 0.05) qualifying cows were detected in estrus after ECP compared with controls. Compared with controls and in response to ECP, estrus occurred 17 to 20 h earlier (P < 0.01) and was of greater (P < 0.05) intensity. The AMS and ET determined 71 and 74% of cows to be in estrus, respectively. Of cows exposed to the AMS, HW, or ET, 62 to 74% were detected in estrus and more than 94% subsequently ovulated. In contrast, of the residual cows not detected in estrus, 60 to 76% ovulated in the absence of detected estrus. Only ECP was successful in inducing more estrus expression and, proportions detected in estrus never exceeded 80%. Given the large proportion of cows ovulating in the absence of estrus, further research is warranted to determine if conception is achievable by inseminating cows not detected in estrus by 80 h post-PGF[subscript 2α].

Thesis (Ph. D.) -- University of Maryland, College Park, 2007.
Thesis research directed by: Dept. of Animal and Avian Sciences. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Thesis (M.S.)--University of Nevada, Reno, 2008.
"December, 2008." Includes bibliographical references (leaves 27-31). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2009]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.

Thesis (B.S.)--California Polytechnic State University, 2009.
Project advisor: Stan Henderson. Title from PDF title page; viewed on Jan. 21, 2010. Includes bibliographical references. Also available on microfiche.

An estrus synchronization trial was conducted to determine the efficacy of adding an injection of gonadotropin releasing hormone (GnRH) at initiation of the controlled intravaginal drug releasing device (CIDR®) progesterone synchronization protocol in heifers. Nulliparous (n=121) beef heifers were randomly assigned to one of two treatment groups. All heifers received a CIDR® implant at the initiation of the breeding season. Half of the heifers (Select Synch) received an injection of GnRH. Heifers in the Select Synch treatment group had a lower numerical response (76.7% versus 88.3%) to treatment (detected in heat) and an overall lower artificial conception rate (46.0% versus 53.3%), but no statistical difference was detected. Days to conception and artificial insemination conception rates for both groups were similar for all heifers inseminated. Three hundred multiparous Hereford, crossbred and composite beef cows were assigned to one of two breeding groups (Early and Late) based on calving date and randomly assigned to receive an injection of GnRH at the time of CIDR® insertion (Select Synch). The addition of GnRH did not impact the percentage of cows detected in estrus or days to conception. Conception rates were not affected by the addition of GnRH (Select Synch), however cows in the early breeding group were more likely to become pregnant (58% versus 45%) by artificial insemination (P<0.02). An experiment evaluated the efficacy of the CIDR® protocol to synchronize estrus in Arizona Holstein dairy cows (n=696). Cows assigned to the CIDR® protocol (n=337) received a CIDR® insert at the end of the voluntary waiting period (55 days). CIDR®s were removed and an injection of prostaglandin was administered seven days after insertion. There was no difference due to CIDR® treatment in number of services per conception or first service conception rate. CIDR® treatment reduced days to first service, days open at first service, and days open (P<0.02). Warm season had a deleterious effect on number of services, days to first service, first service conception rate and days open (P<0.0001). In summary, estrus synchronization improved postpartum reproductive performance; however, thermal stress continues to be a major barrier to reproductive efficiency.

The objectives of the current study were: 1) to examine serum bPAG concentration during pregnancy, and in the post-partum period in relation to the overall nutritional and metabolic status and post-partum anoestrous period; 2) to investigate bPAG decay models for postulating distribution and metabolism of bPAG in the blood circulation using half-life (t1/2) and to compare the t1/2 values between breeds and nutritional treatments for the clearance of bPAG; 3) to examine the suitability of the radioimmunoassay (RIA) for measuring bPAG in urine, saliva and milk, to investigate temporal relationships between bPAG in these fluids and that in the serum, and to assess the potential of bPAG in these fluids for pregnancy diagnosis in cows. Estimation of total bPAG disappearance from plasma per day during week 1 post-partum did not differ between the breeds. Urinary bPAG, over the same period of time, was lower for Welsh Black than Simmental and Charolais cows (0.45 vs 0.53 and 0.59 nmol (s.e.d 0.03) p<0.05) but not for Aberdeen Angus cows (0.48 nmol); bPAG in saliva was lower for Welsh Black than Charolais and Aberdeen Angus cows (1.65 vs 2.42 and 2.49 nmol (s.e.d 0.11) p<0.05) but not for Simmental cows (1.44 nmol/1), and bPAG measured in milk (whole) was lower for Charolais than Simmental cows (0.26 vs 0.47 nmol (s.e.d 0.06) p<0.05) but not for Aberdeen Angus (0.38 nmol/1) and Welsh Black cows (0.37 nmol/1). Total body elimination of bPAG in urine, saliva and milk accounted only for 5.28 % of the total plasma bPAG. Total body elimination of bPAG in urine, saliva and milk accounted for only 5.28 % of the total plasma bPAG. The remaining 94.72 % of bPAG may have been metabolished and was undetectable by the current RIA technique. A theoretical assessment for potential use of bPAG RIA for pregnancy diagnosis using urine, saliva and milk showed that the minimum detection limits of measuring bPAG in these fluids were reached and / or exceeded by Day 200 of gestation, or later. Consequently, assay of bPAG in these fluids for early pregnancy diagnosis would not be appropriate unless the sensitivity of the assays is improved considerably, or prior assay sample extraction/concentration is carried out.

Chromium can act either as an essential micronutrient or a chemical carcinogen, depending on its oxidation state. Of the two most stable chromium oxidation states, Cr(VI) is a known carcinogen, while Cr(III) is an essential element. Determination of total Cr cannot therefore be used to evaluate food safety of dairy products, as speciation is required for accurate assessment of potential toxicity. In this study, total Cr was determined by DRC-ICP-MS after mineralisation of freeze-dried milk samples. Chromabond NH2 ion-exchange columns were used to separate Cr(VI) from Cr(III). During the separation process, Cr(VI) was selectively adsorbed onto the Chromabond NH2 column. The retained Cr(VI) was subsequently eluted with two column volumes of 2 M HNO3 and diluted to a final volume of 10 mL. After separation, the Cr(VI) was quantified by DRC-ICP-MS, using O2 as the reactive gas, to alleviate polyatomic ion interference. An O2 gas flow rate of 0.85 ml/min and a high-pass rejection parameter q (Rpq) ¼ 0.5, provided the best compromise signal-to-noise ratio. The method was validated through determining the recovery in milk samples spiked with Cr(VI). The recoveries were quantitative and ranged from 96.4 to 99.2%. A whole milk powder reference material (NIST SRM 8435) was used to evaluate the accuracy of the total Cr quantification method. The observed value showed concordance with the certified value. The limits of detection (LOD) were 0.091 and 0.085 mg/L for total Cr and Cr(VI), respectively. These findings are important for the determination of maximum residue levels (MRLs) of Cr(VI) in dairy products.

Three milk, fat yield and final score type records were simulated for each cow in 20 herds of 200 cows over 13 years. At completion of the simulation, cows were ranked by different selection methods and the top 2% were chosen to be bull dams. Preferential treatment was simulated by increasing milk and fat yields by 8, 16, 32, and 48% in separate copies of the simulation. Preferential treatment was given to a limited number of cows in copies of the original herds based on 8 strategies. Cows were chosen to receive preferential treatment for 2nd and 3rd records based on phenotypic records and ETA’s alone and in combination with a phenotypic minimum for final score type. Cows were also chosen to be biased in all records based on phenotypic records of dam, parent average ETA, maternal line and final score type. Bull dam selection methods compared used 2:2:1 milk:fat:type indexes of cow Predicted Transmitting Abilities (PTA), first lactation PTA, (PTA-F), PTA after requiring phenotypic minimums, (PTA-P), 3-generation Pedigree Index (PI-3) and PTA after preselection on 3-generation Pedigree Index (PI-3/PTA). Comparison criterion was average merit on a 2:.2:.1 weighting of true transmitting abilities for milk, fat and type for cows selected in each of 3 replicates of the cow population that were started with different random number seeds. Selection methods PTA and PTA-F gave the highest average true breeding values when no bias was present, and both methods were robust to bias levels of 8 and 16% mean response, and continued to give the best results at these levels for all bias patterns studied. In general, selection on PI-3 and PTA-P gave poor results and should not be considered viable selection methods. Selection ability of PTA was greatly decreased at the 32 and 48% bias levels. Selection on PTA-F continued to be effective when bias did not occur in the first lactation or when bias was based on type score, while selection on PI-3PTA was unaffected by bias at any level. Requiring a high level of 3-generation Pedigree Index before selection on PTA appears useful for selecting bull dams when very high levels of bias are present.
Master of Science

The objective of the first study was to quantify the effects of feeding Schizochytrium sp. microalgae (SP-1, Alltech, Inc., Nicholasville, KY) on milk fat and DHA content. Eight cows were fed: 0, 100, 300, or 600 g of algae per day. Fat percentage was greater (P < 0.05) for cows on treatments 0 g and 100 g than for cows on treatments 300 g and 600 g (P < 0.05). Docosahexaenoic acid in milk was greater for cows on treatment 300 and 600 than for cows on treatment 0 and 100 (P < 0.05). The objective of the second study was to assess yeast supplementation effects on high and low forage dairy cow diets. Four cows were assigned to 1 of 4 treatments: 1) low forage (LF), 2) low forage with 10 g/d yeast (Yea-Sacc®; Alltech Inc., Nicholasville, KY; LFY), 3) high forage (HF), or 4) high forage with 10 g/d yeast (HFY). Only rumination time and DMI were influenced by treatment (P < 0.01). Dry matter intake was 17.05, 13.41, 19.44, and 20.29 ± 1.40 kg/d and rumination time was 442.88, 323.09, 433.34, and 475.50 ± 21.93 min/d for cows on the LF, LFY, HF, and HFY treatments, respectively.