Giving lactating sows altrenogest reduces low birthweight piglets
A team of Brazilian researchers evaluated the effect of altrenogest supplementation during lactation on reproductive performance of primiparous sows. They published about their findings in Theriogenology.
Genetic selection for hyperprolific sows has increased the proportion of low birthweight piglets, birthweight variation within the litter, and pre-weaning mortality. Dietary supplementation of altrenogest is known to be beneficial for oestrus synchronisation. However, little is known about altrenogest impact on reproductive performance of primiparous sows.
Data collection
The researchers used 96 pregnant primiparous sows for this trial. They used bump feeding strategy in the last third of pregnancy to improve piglets’ birthweight and maintain sows’ adequate body condition. The team randomly allocated sows into 2 experimental groups. They fed 20 mg altrenogest during the last 6 days of lactation to the first group of sows and provided no supplements to the other group.
They performed oestrus detection twice daily and artificially inseminated sows after the onset of oestrus. The team recorded body weight and body condition score of sows before the trial and when entering the farrowing room. They collected blood samples for plasma progesterone analysis and recorded total placental weights to determine placental efficiency. In addition, they documented the total number of piglets born, born alive, stillborn, and mummified, total litter birthweights, and the individual piglet birthweight.
Moreover, they calculated the ratio between the number of piglets born in the first and second farrowing to determine the occurrence of the second litter syndrome. Finally, they euthanised 10 primiparous sows for morphological analysis of the genital tracts.
Impact on production and reproduction performance
Dietary supplementation of altrenogest had no impact on the body weights and body condition scores of primiparous sows. In addition, short-term altrenogest treatment at the end of lactation had no improving impact on the reproduction performance of sows.
Impact on plasma progesterone levels and birthweight
Supplementing altrenogest increased plasma progesterone concentrations earlier after oestrus onset. In addition, altrenogest reduced the proportion of male piglets in the low birthweight category.
Impact on the genital tract of sows
Dietary supplementation of altrenogest increased the length of uterine tubes of sows, and the proportion of endometrial glands and blood vessels. On the other hand, feeding altrenogest decreased the proportion of connective tissue and glandular area in the genital tract of sows.
Conclusions
The authors concluded that short-term altrenogest supplementation in the last week of lactation, reduces the proportion of low birthweight piglets. This reduction is due to the increase in progesterone levels after oestrus onset and improvement in the uterine environment which are important for embryo survival and development.
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