title: Impact of amino acid nutrition during lactation on luteinizing hormone secretion and return to estrus in primiparous sows.
abstract: The impact of the dietary amino acid regimen of primiparous sows on LH secretion and weaning-to-estrus interval was evaluated. Thirty-six sows, nursing litters of 13 pigs, were allocated daily 6 kg of a corn-soybean meal diet containing a high (HP, 1.20% lysine) or low (LP, .34% lysine) protein content during a 23-d lactation. Dietary lysine concentration was achieved by altering the ratio of corn and soybean meal in the diet. Plasma LH, ACTH, and estradiol-17beta were evaluated at 15 min, hourly, and at 6-h intervals, respectively, during 6-h periods on d 0, 5, 10, 15, and 20 of lactation. Sows were checked daily for estrus from weaning to 45 d postweaning. Sows fed the LP and HP diets consumed 4.41 and 4.98 kg of feed daily during lactation. The LP sows weighed less (P < .05), had lighter (P < .05) litters at weaning, and had (P < .05) extended weaning-to-estrus intervals. Mean and baseline LH concentrations and LH pulses/6 h were lower (P < .01) in LP sows, and the differences between LP and HP sows were established by d 10 of lactation. Plasma estradiol and ACTH concentrations were not altered by diet. Mean LH concentrations on d 5 and 10 of lactation were correlated (r = -.54 and -.56, respectively, P < .01) with weaning-to-estrus interval. Also, mean LH concentrations on d 10 were correlated (P < .05) with the magnitude of dietary lysine deficiencies relative to demand for milk synthesis on d 0 to 5 and d 5 to 10 (r = -.39 and -.49, respectively). Inadequate dietary amino acid intake in sows during early lactation results in lower LH secretion by d 10 postpartum and is associated with increased weaning-to-estrus interval.
authors.affiliation: Department of Animal Science, Iowa State University, Ames 50011, USA.
authors.forename: D B
authors.initials: DB
authors.lastname: Jones
authors.forename: T S
authors.initials: TS
authors.lastname: Stahly
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood; D000596:Amino Acids / Q000008:administration & dosage* / Q000494:pharmacology; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001835:Body Weight; D004044:Dietary Proteins / Q000494:pharmacology*; D004958:Estradiol / Q000097:blood; D004971:Estrus; D005260:Female; D007774:Lactation; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism*; D010298:Parity; D013552:Swine / Q000097:blood / Q000502:physiology*
chemical_list: D000596:Amino Acids; D004044:Dietary Proteins; D004958:Estradiol; D000324:Adrenocorticotropic Hormone; D007986:Luteinizing Hormone