School of Agriculture, Food and Ecosystem Sciences - Theses

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Author: Tritton, Sally Margaret Jane × End date: 1997 × Start date: 1990 × Type: Masters Research thesis × Subject: Feeding and feeds × Subject: Swine ×

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    The influence of concentrations of dietary lysine and energy offered during lactation on the lactation and subsequent reproductive performance of the first-litter sow
    Tritton, Sally Margaret Jane ( 1996)
    The first-litter sow has lower lactation and subsequent reproductive performance than older parity animals. The experimental work in this thesis was conducted to elucidate the influence of dietary energy and protein concentration during lactation on the lactation and subsequent reproductive performance of first-litter sows, whose litters were weaned at 3-4 weeks of age. In the first experiment, 140 first-litter sows were offered one of five diets, ranging in lysine content from 6.2 to 15.1 g/kg. Voluntary feed intake and sow liveweight loss were unaffected by dietary lysine concentration. However sow backfat loss was lowest for sows offered the lowest lysine diet and tended to plateau at a dietary lysine level of 10.6 g/kg. Piglet preweaning growth responded in a curvilinear manner to increasing lysine concentration. The results also indicated for sows nursing 9 or more piglets, that weaning to mating interval decreased with increasing sow dietary lysine concentration. Subsequent litter size was significantly higher for sows offered the two higher lysine diets during lactation, compared to the two lower lysine diets (10.7 vs 9.6 born alive, P<.05; s.e.d. 0.5). In the second experiment, 175 first-litter sows were offered one of five diets with a similar lysine:digestible energy (DE) ratio (0.88 to 0.85 g/MJ) but ranging in DE content from 12.6 to 15.1 MJ/kg. Voluntary food intake and piglet growth rate during lactation were unaffected by DE content of the diets. Sow liveweight loss during lactation declined with increasing energy content up to 13.8 MJ DE/kg. Backfat loss during lactation tended to be highest for sows offered the diet of lowest DE content and declined with increasing energy content up to 15.1 MJ DE/kg. The subsequent weaning to remating interval and litter size were unaffected by dietary DE content. In the third experiment, 204 first-litter sows were offered diets containing either 8.1 or 13.3 g lysine/kg during lactation. Voluntary food intake in lactation, piglet preweaning growth, sow liveweight and backfat loss during lactation, weaning to mating interval and subsequent litter size, were unaffected by dietary lysine concentration of the lactation diet. The number of corpora lutea and embryos were also not influenced by dietary lysine concentration during the preceding lactation. However, the data from those sows whose preweaning litter growth was in excess of 40 kg demonstrated a significant improvement in number of corpora lutea at the higher dietary lysine level. The results indicate that sow liveweight and fat losses during lactation appear to be more responsive to changes in DE concentration than changes in dietary lysine level. However, lysine concentration may limit piglet growth rate, weaning to mating interval and subsequent litter size. The results also suggest that improvements in subsequent litter size, observed when sows are offered high dietary lysine levels during lactation, may be due to an improvement in ovulation rate. These experiments suggest that current amino acid recommendations for lactating first-litter sows are inappropriate and may be constraining both milk production and subsequent reproductive performance.