Academic literature on the topic 'Split weaning'

An experiment was undertaken to investigate the influence of split-weaning of litters 7 d before full weaning on the growth of piglets and the reproductive performance of sows. The litters of 27 Yorkshire × Landrace sows were assigned to be either split-weaned (heaviest piglets removed at 21 d of lactation; n = 13) or to act as controls (all piglets weaned at 28 d of lactation; n = 14). The influence on sow and litter performance was monitored. During lactation, mean sow feed intakes in the split-weaned and control groups were 6.9 ± 0.1 and 6.7 ± 0.2 kg d−1, respectively. The diet was formulated to provide 12.3 MJ DE kg−1 and 15.7% crude protein. Nursing piglets were allowed free access to a 20% crude protein creep feed from 7 d of age. Weaned piglets were fed ad libitum a commercial starter diet containing 18% crude protein. Split-weaning had no effect on either the weaning to estrus interval or subsequent litter size (4.5 ± 0.1 vs. 4.3 ± 0.4 d and 12.7 ± 0.9 vs. 13.0 ± 0.9 pigs, for split-weaned and control sows, respectively). However, while control sows lost weight between 21 and 28 d of lactation, the split-weaned sows gained weight (P < 0.02). There was no treatment effect on body weights of nursing piglets but weaning of the heavy piglets at 21 d resulted in a lower (P < 0.05) body weight at 28 d. On days 21 and 28, four sows from each group were blood sampled via indwelling vena caval cannulae at hourly intervals for 10 h. Also, samples were taken every 15 min for 4 h on these days. No treatment effect was noted for mean serum concentrations of luteinizing hormone (LH) or follicle stimulating hormone (FSH). Similarly, there was no effect on LH pulse frequency or amplitude. It is concluded that, in the absence of excessive sow weight loss or prolonged weaning to estrus intervals, the introduction of a split-weaning regime will not enhance sow or litter performance. Key words: Split-weaning, piglet growth, sow performance

The mechanisms of increased growth of small piglets following split weaning were studied using a total of 10 sows and 100 piglets. Sows and their litters were allocated to a treatment group (piglets split-weaned) or control group (no piglets split-weaned). At day 22 of lactation, piglets in each litter were classified as either 'heavy' or 'light', with equal numbers in each group. 'Heavy' piglets were removed from sows at day 22 (s.e.m. 0.17) in split-weaned litters while 'light' piglets remained with their mothers for an extra week. At 29.5 (s.e.m. 0.21) days of age, sows from both split-weaned and control litters were weaned. Milk consumption was estimated between days 16 and 19 and on day 24 of lactation by weighing piglets before and after sucking. During milk letdown, the teats that piglets sucked from were noted. A video recorder was used to determine the frequency of natural sucklings, the proportion of unsuccessful sucklings, and the time taken for piglets to consume milk during ejection, over a 16-h period before and after split weaning. 'Light' piglets in split-weaned litters grew 61% faster (P < 0.001) than their counterparts in control litters and were 15% heavier (P < 0.01) at weaning. This was explained by a 49% increase in milk intake (64 v. 43 g/sucking, P 5 0.001). Increased milk intake was due to multiple teat swapping with an associated longer duration of sucking during letdown. 'Heavy' piglets weaned at 22 days were lighter at 29 days than their counterparts in control litters (P < 0.01). Gains in growth made by 'light' piglets in split-weaned sows over their counterparts in control litters had disappeared by the time pigs were 9 weeks old, and piglets classed as 'heavy' at day 22 of lactation remained heavier ( P < 0.001) at 62 days of age irrespective of treatment.

With progressive reduction in piglet mortality and increase in the number of piglets reared for litter over recent years, there has been interest in weaning the larger piglets in large litters several days prior to the planned final weaning date in an attempt to improve the growth rate and size of the smaller piglets prior to weaning. Such prior removal of larger piglets before their smaller litter mates are weaned is termed ‘partial’ or ‘split’ weaning’ and this practice was evaluated in a controlled experiment in terms of the liveweight gain to weaning of the smaller piglets within the litter.

’Partial’ or ‘split’ weaning involves the earlier weaning of part of the litter before the normal weaning date. There have been isolated reports which claim that such a practice can reduce final weaning to service and conception interval and increase the size of the subsequent litter. However, these possible effects have not been quantified adequately and accordingly a study was carried out to further evaluate this practice.The study was conducted on a 700 sow commercial unit in Aberdeen-shire with crossbred Large White (LW) x Landrace (LR) sows mated to LW, LR or LW x LR boars. Sows and litters were accomodated in conventional farrowing pens and weaning took place when litters averaged 17 days of age. Following weaning, sows were transferred to dry sow stalls adjacent to boar pens. Newly weaned pigs were transferred to flat-deck nursery accomodation.

Abstract Recent increases in litter size in commercial sows have been accompanied by higher pre-weaning mortality (PWM) and lower weaning weights. The objective was to determine effects of litter size and feeding liquid milk replacer during lactation (using an automated feeder) on piglet performance. A split-plot design was used with a 2x2 factorial arrangement of treatments: Milk Replacer (MR; main plot; Unsupplemented vs. Supplemented); Litter Size [LS; sub-plot; Low (2 piglets less than functional teat number) vs. High (2 piglets greater than functional teat number)]. Cross-fostering was carried out at 24 h after birth to create treatment litters with similar gender ratio, proportion of cross-fostered piglets, and average and CV of birth weight. Milk replacer was available from 24 h after birth to weaning. Piglets were weighed on d 1 and 20 (weaning) after birth; all PWM was recorded. Growth data were analyzed using PROC MIXED of SAS; PWM data were analyzed using PROC GLIMMIX. Models accounted for fixed effects of MR, LS, the interaction, and random effects of replicate and replicate by MR interaction. There were no MR by LS interactions (P &gt; 0.05) for any measurement. Supplemented compared with Unsupplemented litters had similar (P &gt; 0.05) litter size at weaning and PWM, but greater (P &lt; 0.05) average piglet and total litter weaning weight (Table 1). The High LS treatment had greater (P &lt; 0.05) litter size and total litter weight at d 1 and weaning, but higher (P &lt; 0.05) PWM and lower (P &lt; 0.05) average piglet weaning weight. In conclusion, supplementing piglets with liquid milk replacer increased weaning weight with no effect on PWM, and increasing litter size above sow teat number had negative effects on both PWM and piglet weaning weight.

In lactation, sows are typically anoestrus, with ovulation occurring three to seven days after weaning at approximately 24 days post-partum. Increasing piglet age to greater than 28 days improves piglet performance and welfare; however, it also results in reduced sow farrowing frequencies, making the commercial adoption of increasing piglet weaning age unsustainable. Stimulating a sow to ovulate in lactation represents a solution as it enables lactation length to be increased whilst maintaining reproductive efficiencies. The aims of the research reported in this thesis were to investigate mechanisms to reliably stimulate a lactation oestrus in multiparous and primiparous sows. Secondly, to determine the effect of these strategies on piglet growth, subsequent pregnancy rate, farrowing rate and litter size. The mechanisms investigated were focused on: reducing the suckling input to the sow through split weaning or low-confinement alternative lactation housing; and fence, or full physical, boar exposure. The importance of a reduced suckling input was demonstrated in Chapter Two. The proportion of sows expressing a lactation oestrus increased as the number of piglets weaned on day 18 of lactation increased from zero, three, five to seven. Additionally, early weaning did not compromise growth of the split weaned piglets, with both early and late weaned piglets experiencing similar body weights by day 40 of age. Chapter Three evaluated the effect of full physical boar exposure commencing at day 10, 14 or 18 postpartum on the incidence of lactation oestrus in primiparous and multiparous sows. A high proportion of multiparous sows expressed a lactation oestrus in response to boar exposure compared to first parity sows; however, the summer months impacted this expression. No benefits of commencing boar exposure before day 18 post-partum on lactation oestrus expression were observed. Chapter Four coupled full physical boar exposure with split weaning of piglets at day 18 post-partum within a commercial piggery. Boar exposure was effective at stimulating a lactation oestrus in multiparous sows whereas primiparous sows require, in addition to boar exposure, a reduction in suckled litter size. A high incidence (24%) of lactating multiparous sows that received no stimulation spontaneously ovulated before weaning resulting in a prolonged weaning to oestrus interval. These results suggest that for the modern sow, weaning is not necessary for ovulation. Lastly, Chapter Five demonstrated that low confinement lactation housing from seven days post-partum, in combination with fence line boar exposure, was not sufficient to stimulate a lactation oestrus. Overall, split weaning to seven piglets in conjunction with physical boar exposure resulted in the highest proportion of lactation oestrus expression with this response greater in multiparous sows than primiparous sows. Season affected the proportion of lactation oestrus expression, and this requires further investigation. Furthermore, the incidence of spontaneous ovulation during lactation suggests that the inhibition of LH release during lactation is less severe in modern genotypes. In conclusion, this thesis has demonstrated that boar exposure effectively stimulates lactation oestrus with a further increase observed when a distinct reduction in the suckling stimulus has occurred, particularly in the multiparous sow.
Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Animal and Veterinary Sciences, 2015.

This paper is Winnicott’s account of the Depressive Position as a normal stage in the development of healthy infants, an achievement mostly belonging to the weaning age. It does not mean healthy infants pass through a stage of depression. Emotionally unhealthy, depersonalized babies lack the preconditions for this achievement. The mother holds the situation in time, so that the baby may experience ‘excited’ relationships and meet the consequences. Integration in the child’s mind of the split between the child-care environment and the exciting environment (the two aspects of mother) depends on good-enough mothering and the mother’s survival. The baby experiences this while the mother is holding the situation and the infant realizes that the ‘quiet’ mother was involved in the full tide of instinctual experience, and has survived. Instinctual experience brings anxiety and guilt but clinically children are sometimes without a sense of guilt, although they can go on to develop it. In the inner world of the individual who has achieved the depressive position there is on balance a reduced depressive mood and their reaction to loss is grief, or sadness. Where there is some degree of failure at the depressive position the result of loss is depression. The child who has reached the depressive position can get on with the problem of triangular interpersonal relationships: the classical Oedipus complex.