Swine foetal myogenesis in different gestation periods

Effects of oestrous synchronization with altrenogest in gilts on endometrial and embryonic characteristics

The use of altrenogest (ALT) supplementation for oestrous synchronization improves subsequent reproductive performance of gilts and sows. However, the causes of this improvement in reproductive performance after ALT treatment are not fully/clearly understood. The objective of this study was to evaluate the effects of ALT supplementation for oestrous synchronization in gilts on the endometrial glands and embryonic development characteristics at 28 days of pregnancy. Pregnant gilts were divided into two experimental treatments: Control (did not receive ALT; n = 9 gilts) and ALT (ALT feeding at 20 mg/day for 18 days; n = 9 gilts). At 28 days of pregnancy, six gilts from each treatment were slaughtered, and reproductive tracts were immediately evaluated. There was no statistical difference (P > 0.05) between treatments regarding ovulation rate, number of embryos, number of vital embryos and number of non-vital embryos. Embryo weight, length and embryonic vesicle weight were lower in ALT treatment compared with Control (P < 0.01), and it was lower in the cervical uterine region compared with apex uterine region, respectively (P < 0.05). Higher values of gland duct area, gland duct perimeter, percentage of the glandular area and total endometrial area were observed in ALT treatment compared with Control (P < 0.05). The use of ALT during 18 days for oestrous synchronization in gilts increased the gland duct area, perimeter and total endometrial area but did not increase the embryo number and embryo size at day 28 of pregnancy.

Supplementing 2 g per day bovine lactoferrin from late gestation until weaning did not improve lactation performance of mixed parity sows

Context Lactoferrin is a non-haem binding protein that possesses antimicrobial, antioxidant and anti-inflammatory properties. A previous study showed lactoferrin supplementation from early gestation to weaning improved lactation performance in primiparous sows; however, it is unknown whether the supplementation within a more specified duration (from late gestation to weaning) can improve lactation performance in multiparous sows, which limits its commercial application. Aims This experiment investigated the effects of 2 g/day bovine lactoferrin supplementation from late gestation to weaning on lactation performance in mixed parity sows. Methods Forty-seven primiparous sows and 167 multiparous sows (up to parity 5; Large White × Landrace, PrimeGro Genetics, Corowa, NSW) were allocated to either a Control diet (2 g/day casein) or Lactoferrin supplement diet (2 g/day lactoferrin) when entering the farrowing house in late gestation (101 ± 4.6 days, mean ± s.d.) balanced by parity (2.4 ± 1.80, mean ± s.d.). Sows were housed individually in farrowing crates and fed the experimental diets until weaning (26 ± 2.5 days, mean ± s.d.). Farrowing outcomes and lactation performance were recorded. Key results Lactoferrin supplementation did not affect the number of piglets born alive, number of stillborn piglets, number of mummified fetuses, the percentage of born-light piglets (≤1.1 kg) or piglet pre-fostering survival rate. Cross-fostering within the first 48 h standardised the litter size and litter weight between dietary treatments. Piglet pre-weaning survival rate, litter weight gain, average daily gain of piglets, or coefficient of variation of piglet growth rate was not affected by lactoferrin supplementation. Daily feed intake during lactation, bodyweight and backfat thickness of sows at weaning were similar between the dietary treatments. Conclusions Two grams per day lactoferrin supplementation from late gestation to weaning did not affect lactation performance in mixed parity sows. Implications The effectiveness of lactoferrin supplementation may depend upon the duration of supplementation, which should be optimised in future studies.