Parturition body size and body protein loss during lactation influence performance during lactation and ovarian function at weaning in first-parity sows1

Abstract

We investigated the effect of body protein mass at parturition and different degrees of body protein loss in lactation on sow performance. In a 2 x 2 factorial arrangement, 77 Genex gilts were fed to achieve either a standard or high body mass at parturition and to lose either a moderate (MPL) or high (HPL) amount of protein in lactation. Pregnant gilts were fed either 24.4 MJ of ME, 266 g of CP, and 11 g of lysine/d or 34.0 MJ of ME, 436 g of CP, and 20 g of lysine/d resulting in divergent (P < 0.01) live weights (165 vs. 193 kg) and calculated protein masses (24.3 vs. 30.0 kg) and slightly different backfat depths (20.0 vs. 22.8 mm; P < 0.05) at parturition. Diets fed during lactation were formulated to deliver 731 g of CP and 37 g of lysine/d or 416 g of CP and 22 g of lysine/d to induce differential body protein mobilization. Sows were slaughtered at weaning (d 26), and the weight of the organs and the lean, fat, and bone in five primal cuts was measured. The external diameter of the eight largest follicles on each ovary was recorded, and the follicular fluid from these follicles was collected, weighed, and analyzed for estradiol. Losses in lactational live weight (26 vs. 20 kg; P < 0.01) and calculated protein mass (17.8 vs. 10.7%; P < 0.001) were greater, and the carcass lean mass at weaning was 10% lighter (P < 0.05) in HPL sows. Backfat (5.1 +/- 0.8 mm; P = 0.29) and calculated fat mass (25.8 +/- 1.5%; P = 0.84) losses did not differ between treatments. Both sow body mass (P < 0.05) and lactation protein loss (P < 0.01) affected litter growth rate. Litter growth rate decreased (P < 0.05) at the end of lactation in HPL sows once these sows had lost 10 to 12% of their calculated protein mass. Ovarian follicular development was most advanced in high body mass sows that lost the least protein; these sows had the heaviest (P < 0.05) uterine weight and highest (P < 0.05) follicular fluid estradiol concentration. Follicular development was least advanced in standard body mass sows that lost the most protein. These sows had the lowest (P < 0.05) muscle:bone ratio at weaning and likely lost the largest proportion of their muscle mass compared with the other treatments. In conclusion, ovarian function at weaning and litter performance was higher in high body mass sows and in sows that lost the least protein in lactation, suggesting that a larger lean mass may delay the onset of a decrease in performance in sows that lose protein in lactation.

Dietary protein restriction during lactation in primiparous sows with different live weights at farrowing: II. Consequences on reproductive performance and interactions with metabolic status

“…The detrimental effect of protein restriction has already been reported on ovulation rate at the first estrus after weaning [10]. It is also consistent with data showing an impaired folliculogenesis at or after weaning in sows that lost a high amount of body protein during lactation compared with sows that lost a moderate amount of protein [11,35,36]. Such impairment was illustrated by a lower proportion of large follicles and reduced concentrations of oestradiol and/or IGF-I in follicular fluid.…”

“…Such impairment was illustrated by a lower proportion of large follicles and reduced concentrations of oestradiol and/or IGF-I in follicular fluid. Clowes et al [11] also reported that the sow's body mass at parturition has a greater effect on ovarian characteristics than protein loss during lactation. This was in agreement with the fact that heavy sows in the present experiment were less affected by protein loss than light sows, concerning ovulation rate.…”

“…Clowes et al [11] conjectured that the availability of certain AA in the peripheral circulation could directly influence ovarian function. This is supported in the present experiment by the positive relationship observed between several AA and ovulation rate.…”

“…In lactating primiparous sows, a severe deficit in dietary protein has been demonstrated to compromise lactation [6] and subsequent reproduction, especially the weaningto-estrus interval (WOI) [5,8,9]. However, this detrimental effect on WOI or ovarian function at weaning was not observed in primiparous sows that had large body reserves at farrowing [10,11]. Evidence exists that WOI is influenced not only by body reserve loss during lactation, but also by absolute amounts of reserves at farrowing and weaning [12][13][14][15].…”

Impact of feed restriction on the performance of highly prolific lactating sows and its effect on the subsequent lactation

“…Sows under severe catabolism present reduced IGF-1 levels (Patterson et al, 2011), inducing the mobilization of endogenous protein (Zak et al, 1997). Protein mass losses >12% during lactation may reduce follicle number and diameter, and decrease IGF-1 levels in sows submitted to dietary protein restriction during lactation (Clowes et al, 2003a and2003b). Schenkel et al (2010) recently reported reduced size of the next litter when sow's body mass and protein mass losses exceeded 8% and 9%, respectively.…”