title: Recombinant porcine somatotropin for sows during late gestation and throughout lactation.
abstract: Two experiments were conducted to evaluate whether administration of recombinant porcine somatotropin (pST) to sows (Hampshire-Yorkshire) enhanced lactational performance. In Exp. 1, sows (n = 84) were fed a corn-soybean meal diet (17.8% CP), or a similar diet with 8% added fat, from d 108 of gestation to d 28 of lactation. Half of the sows fed each diet were injected with 6 mg/d of pST from d 108 of gestation to d 24 of lactation. Diets were fed at 2.27 kg/d from d 108 of gestation until farrowing and then were self-fed during lactation. By d 3 of lactation, litter size was standardized at 8 to 10 pigs per litter. Treating sows with pST resulted in a 10-fold increase (P less than .001) in serum somatotropin at 4 h postinjection. Serum glucose was increased (P less than .01) and serum triglycerides, creatinine, and urea N were decreased (P less than .01) by pST. During the summer, apparent heat stress occurred in pST-treated sows, resulting in 14 deaths. Most (10) of the deaths occurred just before, during, or shortly after farrowing. Fewer (P less than .08) deaths occurred when pST-treated sows were fed the diet with added fat. Sows treated with pST consumed less feed (P less than .10) and lost more backfat (P less than .10) during lactation than controls. Increasing the dietary fat did not prevent these changes. Weaning weights of pigs and milk yield of sows (estimated by deuterium oxide dilution) were not affected by pST treatment. In Exp. 2, sows (n = 42) were injected weekly with 0 or 70 mg of pST on d 3, 10, 17, and 24 of lactation. Litters were standardized by d 3 at 8 to 10 pigs, and sows were fed the same control (low fat) diet as in Exp. 1. Sows treated with pST consumed less feed and lost more weight and backfat during lactation than untreated sows. Litter size, average pig weaning weights, and milk yield were not influenced by pST treatment. These data indicate that a 6-mg daily injection of pST from 6 d prepartum to d 24 of lactation or a 70-mg weekly injection of pST from 3 d postpartum to d 24 of lactation does not increase milk production in lactating sows.
authors.affiliation: Department of Animal Sciences, University of Kentucky, Lexington 40546.
authors.forename: G L
authors.initials: GL
authors.lastname: Cromwell
authors.forename: T S
authors.initials: TS
authors.lastname: Stahly
authors.forename: L A
authors.initials: LA
authors.lastname: Edgerton
authors.forename: H J
authors.initials: HJ
authors.lastname: Monegue
authors.forename: T W
authors.initials: TW
authors.lastname: Burnell
authors.forename: B C
authors.initials: BC
authors.lastname: Schenck
authors.forename: B R
authors.initials: BR
authors.lastname: Schricker
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D004041:Dietary Fats / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects; D004971:Estrus / Q000187:drug effects; D005260:Female; D013006:Growth Hormone / Q000008:administration & dosage / Q000009:adverse effects / Q000097:blood / Q000494:pharmacology*; D006358:Hot Temperature / Q000009:adverse effects; D007774:Lactation / Q000187:drug effects*; D008098:Litter Size / Q000187:drug effects; D008892:Milk / Q000032:analysis / Q000378:metabolism; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000187:drug effects*; D011897:Random Allocation; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology; D012621:Seasons; D013312:Stress, Physiological / Q000209:etiology / Q000401:mortality / Q000662:veterinary; D013552:Swine / Q000097:blood / Q000502:physiology*; D013553:Swine Diseases / Q000209:etiology / Q000401:mortality
chemical_list: D004041:Dietary Fats; D011994:Recombinant Proteins; D013006:Growth Hormone