Does duration of teat use in first parity affect milk yield and mammary gene expression in second parity?
Citation
Farmer, C., Amezcua, M., Bruckmaier, R., Wellnitz, O., Friendship, R. (2017). Does duration of teat use in first parity affect milk yield and mammary gene expression in second parity?. Journal of Animal Science, [online] 95(2), 681-687. http://dx.doi.org/10.2527/jas2016.1119
Plain language summary
We know that if a teat is not suckled in first lactation it will produce less milk in second lactation. But for how long must a teat be suckled in first lactation to avoid such a negative effect? Most recent results show that if a teat is suckled for only 2 days in parity 1, its milk yield will not be reduced in parity 2. When comparing lactation lengths of 2, 7 or 21 days in first parity, milk yield of sows in second parity was not affected. There is therefore no advantage to leaving piglets for more than 2 days on a teat in terms of milk yield from that teat in the next parity. This finding is crucial for swine producers because it will impact the management of first-parity sows that have a poor body condition. It would indeed be possible to remove some piglets from thin primiparous sows as of day 3 of lactation in order for these sows to improve their body condition, knowing that milk yield from the less-used teats will not be compromised in the subsequent lactation. This is information that will prove most useful for producers in the decision making relative to management of first-parity sows.
Abstract
It was recently shown that a teat that is not used in the first lactation will have a reduced development and milk yield in the second lactation. In the current study, the impact of imposing a suckling period of 2, 7, or 21 d during the first lactation on piglet performance, milk composition, endocrine status, and mammary gene expression of sows in their second lactation was studied. Pregnant Yorkshire gilts were divided into 3 groups according to lactation length: 1) 2-d lactation (2D; n = 20), 2) 7-d lactation (7D; n = 20), and 3) 21-d lactation (21D; n = 21). After weaning, sows were bred and kept for a second parity. In both lactations, litters were standardized to 12 piglets with 12 functional teats and surplus teats were sealed. In the second lactation, piglets were weighed on d 2, 7, 14, 21 (weaning), 31, and 56 postpartum, and sow feed intake was recorded. On d 110 of gestation and on d 21 of lactation, mammary biopsies were performed on 10 sows per treatment to obtain parenchymal tissue samples for determination of mRNA abundance for PRL, PRLR-LF, STAT5A, STAT5B, LALBA, and IGFBP-5 genes. Milk samples and jugular blood samples were also obtained from sows on d 21 of lactation. Standard composition analyses (DM, fat, protein, and lactose) were done in milk. Concentrations of prolactin, IGF-1, glucose, and urea were measured in blood. There was a tendency for 21D sows to consume more feed than 2D or 7D sows during the first week of lactation (P < 0.10). There was no treatment effect on BW of piglets at any time until d 56 (P > 0.10). Concentrations of prolactin, IGF-1, urea, and glucose in sows on d 21 of lactation were not affected by treatment (P > 0.10). Dry matter, fat, protein, and lactose contents in milk were not altered by treatment (P > 0.10). On d 110 of gestation, PRL gene expression was greater (P = 0.05) in 21D sows than in 7D sows. On d 21 of lactation, gene expression of STAT5B was greater (P = 0.05) and that of IGFBP-5 tended to be lower (P < 0.10) in 7D sows than in 2D sows. The mRNA abundance of LALBA also tended to be lower (P < 0.10) in 2D sows than in 7D sows. Results indicate that increasing the duration of lactation from 2 d to 7 d or to 21 d in first-parity sows did not improve growth rate of their piglets in the subsequent lactation. This suggests that suckling of a teat for 2 d during the first lactation is sufficient to ensure optimal mammary development.