Agroscope, Swine Research Group, 1725 Posieux, Switzerland; Department of Animal Sciences, Laval University, Quebec G1V 1A6, Canada.
AB Vista, Marlborough, Wiltshire SN8 4AN, United Kingdom.
Animal. 2024 Apr;18(4):101130. doi: 10.1016/j.animal.2024.101130. Epub 2024 Mar 12.
To maximize the efficiency of dietary P utilization in swine production, understanding the mechanisms of P utilization in lactating sows is relevant due to their high P requirement and the resulting high inorganic P intake. Gaining a better knowledge of the Ca and P quantities that can be mobilized from bones during lactation, and subsequently replenished during the following gestation, would enable the development of more accurate P requirements incorporating this process of bone dynamics. The objective was to measure the amount of body mineral reserves mobilized during lactation, depending on dietary digestible P and phytase addition and to measure the amount recovered during the following gestation. Body composition of 24 primiparous sows was measured by dual-energy x-ray absorptiometry 2, 14, 26, 70 and 110 days after farrowing. Four lactation diets were formulated to cover nutritional requirements, with the exception of Ca and digestible P: 100% (Lact100; 9.9 g Ca and 3.0 g digestible P/kg), 75% (Lact75), 50% without added phytase (Lact50) and 50% with added phytase (Lact50 + FTU). The gestation diet was formulated to cover the nutritional requirements of Ca and digestible P (8.2 g Ca and 2.6 g digestible P/kg). During the 26 days of lactation, each sow mobilized body mineral reserves. The mean amount of mobilized bone mineral content (BMC) was 664 g, representing 240 g Ca and 113 g P. At weaning, the BMC (g/kg of BW) of Lact50 sows tended to be lower than Lact100 sows (-12.8%, linear Ca and P effect × quadratic time effect) while the BMC of Lact50 + FTU sows remained similar to that of Lact100 sows. During the following gestation, BMC returned to similar values among treatments. Therefore, the sows fed Lact50 could recover from the higher bone mineral mobilization that occurred during lactation. The P excretion was reduced by 40 and 43% in sows fed Lact50 and Lact50 + FTU, respectively, relative to sows fed Lact100. In conclusion, the quantified changes in body composition during the lactation and following gestation of primiparous sows show that bone mineral reserves were mobilized and recovered and that its degree was dependent on the dietary P content and from phytase supplementation during lactation. In the future, considering this potential of the sows' bone mineralization dynamics within the factorial assessment of P requirement and considering the digestible P equivalency of microbial phytase could greatly limit the dietary use of inorganic phosphates and, thus, reduce P excretion.
为了最大限度地提高猪生产中饲料磷的利用效率，了解哺乳期母猪磷利用的机制是很重要的，因为它们的磷需求很高，导致无机磷摄入也很高。更好地了解哺乳期可以从骨骼中动员出来的钙和磷的数量，以及随后在接下来的妊娠期间补充的数量，将能够开发出更准确的磷需求，纳入这一骨骼动力学过程。目的是测量哺乳期根据日粮可消化磷和植酸酶添加量从体内动员的矿物质储备量，并测量随后在妊娠期间恢复的量。在分娩后 2、14、26、70 和 110 天，通过双能 X 射线吸收法测量 24 头初产母猪的身体成分。配制了四种哺乳期日粮，以满足营养需求，但不包括钙和可消化磷：100%（Lact100；9.9 g 钙和 3.0 g 可消化磷/千克）、75%（Lact75）、50%无添加植酸酶（Lact50）和 50%添加植酸酶（Lact50+FTU）。妊娠日粮的配方是为了满足钙和可消化磷的营养需求（8.2 g 钙和 2.6 g 可消化磷/千克）。在 26 天的哺乳期内，每头母猪都会动员体内的矿物质储备。动员的骨矿物质含量（BMC）的平均值为 664 克，代表 240 克钙和 113 克磷。在断奶时，Lact50 母猪的 BMC（BW/kg）趋于低于 Lact100 母猪（线性钙和磷效应×二次时间效应-12.8%），而 Lact50+FTU 母猪的 BMC 仍与 Lact100 母猪相似。在接下来的妊娠期间，BMC 在处理之间恢复到相似的值。因此，饲喂 Lact50 的母猪可以从哺乳期更高的骨矿物质动员中恢复过来。与饲喂 Lact100 的母猪相比，饲喂 Lact50 和 Lact50+FTU 的母猪的磷排泄量分别减少了 40%和 43%。总之，初产母猪哺乳期和随后妊娠期间身体成分的定量变化表明，骨矿物质储备被动员和恢复，其程度取决于日粮磷含量和哺乳期植酸酶的添加。将来，在综合评估磷需求时考虑母猪骨矿化动力学的这种潜力，并考虑微生物植酸酶的可消化磷当量，可以极大地限制日粮中无机磷酸盐的使用，从而减少磷排泄。
