The impacts of diet deprivation and subsequent over-allowance during gestation on mammary gene expression and development and lactation performance were determined by Chantal Farmer from Agriculture and Agri-Food Canada and co-authors there and with La COOP Fédérée.

In their paper published in Journal of Animal Science, the researchers explain that gilts were reared under a conventional (control, CTL; n=59) or an experimental (treatment, TRT; n=56) dietary regimen during gestation.

The experimental regimen provided 70 per cent (restriction diet, RES) and 115 per cent (over-allowance diet, OVER) of the protein and digestible energy (DE) contents provided by the CTL diet. The RES diet was given during the first 10 weeks of gestation followed by the OVER diet until farrowing.

Some gilts (14 CTL and 14 TRT) were slaughtered on day 110 of gestation, and the others were allowed to farrow. Of these remaining sows, 28 (14 CTL and 14 TRT) were slaughtered on day 21 of lactation, and the rest underwent a second lactation.

At each slaughter, mammary tissue was collected for compositional analyses and assessment of gene expression. Milk samples were collected on day 17 of the first lactation. Litter size was standardised to 11±1, and piglets were weighed weekly until day 18 in both parities.

The bodyweight and back fat thickness of TRT first-parity sows were less than those of CTL sows in gestation (P<0.05), and their bodyweight was also lower in lactation (P<0.05). The bodyweight of TRT second-parity sows was still less at mating (P<0.05) and tended to be less on day 1 of lactation (P<0.10) than CTL sows.

There were no differences in piglet growth between CTL and TRT litters in either parity.

Mammary development and mammary gene expression were affected by treatment. There was less parenchymal tissue (P<0.01) at the end of the first gestation in TRT than in CTL sows but parenchymal tissue composition was not altered by treatment.

Relative abundance of IGF-1 (P<0.05), ornithine decarboxylase (P<0.05), signal transducer and activator of transcription 5B (P<0.05), and whey acidic protein (WAP; P<0.01) genes in parenchyma at the end of the first gestation was lower in TRT than in CTL sows, and the effect on WAP genes was still present at the end of the first lactation (P<0.01).

Mammary composition at the end of the first lactation and milk composition were unaffected by treatment.

In conclusion, Farmer and co-authors report that feed deprivation and subsequent over-allowance in gestation had unfavourable effects on sow bodyweight, back fat, mammary development and mammary gene expression at the end of gestation but piglet growth rate over the two parities was not affected by the dam's feeding regimen.

Reference

Farmer C., M-F. Palin and Y. Martel-Kennes. 2014. Impact of diet deprivation and subsequent overallowance during gestation on mammary gland development and lactation performance. J. Anim. Sci. 92(1):141-151. doi: 10.2527/jas.2013-6558

January 2014