title: A regional evaluation of injections of high levels of vitamin A on reproductive performance of sows.
abstract: A regional study involving 443 litters from 182 sows was conducted at 5 cooperating experiment stations to determine the effects of an i.m. injection of vitamin A at weaning and breeding on subsequent litter size of sows. Sows were assigned to 1 of 3 treatments given at weaning and again at breeding: 1) a placebo i.m. injection (2 mL of corn oil), 2) i.m. injection with 250,000 IU of vitamin A (1 mL of vitamin A palmitate in oil), and 3) i.m. injection with 500,000 IU of vitamin A (2 mL of vitamin A palmitate in oil). Corn-soybean meal diets in gestation were formulated to contain 13% CP and 0.60% total Lys. Lactation diets were formulated to contain 17% CP and 0.90% Lys. A common vitamin-mineral premix that supplied 11,000 IU of vitamin A/kg of diet (as-fed) was used by all stations. As expected, station effects were noted for many response measures. Analysis of the data also revealed both treatment x station and treatment x parity interactions for litter size responses. The treatment x parity interactions were stronger than the treatment x station effects, and when the litter size response was separated into early parity sows (parity 1 and 2) and late-parity sows (parity 3 to 6), the treatment x station interactions were no longer present in either subgroup. For sows of parity 1 and 2, litter sizes were increased linearly (P <or= 0.003) for treatment 1 to 3, respectively, for the total (10.15, 12.14, and 13.18), live born (9.70, 11.14, and 12.16), and weaned (8.92, 10.12, and 10.60) piglets. For sows of parity 3 to 6, litter sizes were not affected for treatment 1 to 3, respectively, for the total (11.82, 11.71, and 11.46), live born (10.82, 10.64, and 10.23), and weaned (8.65, 9.01, 8.79) piglets. Piglet BW were affected (P < 0.001) by station and were associated with station differences (P < 0.05) in lactation length. Piglet BW decreased due to vitamin A treatment in parity 1 and 2 sows (linear, P <or= 0.026) and was likely due to the differences observed in litter size. The results of this regional project demonstrated that injection of high doses of vitamin A in young sows at weaning and breeding improves the subsequent number of pigs born and weaned per litter, indicating that vitamin A requirements for maximal performance may vary with age.
authors.affiliation: S-145 Regional Research Committee on Nutrition and Management of Swine for Increased Reproduction Efficiency, Department of Animal and Food Sciences, University of Kentucky, Lexington, Kentucky 40546, USA. mdlind1@uky.edu
authors.forename: M D
authors.initials: MD
authors.lastname: Lindemann
authors.forename: J H
authors.initials: JH
authors.lastname: Brendemuhl
authors.forename: L I
authors.initials: LI
authors.lastname: Chiba
authors.forename: C S
authors.initials: CS
authors.lastname: Darroch
authors.forename: C R
authors.initials: CR
authors.lastname: Dove
authors.forename: M J
authors.initials: MJ
authors.lastname: Estienne
authors.forename: A F
authors.initials: AF
authors.lastname: Harper
mesh_terms: D000367:Age Factors; D000821:Animal Feed; D000818:Animals; D001835:Body Weight; D001947:Breeding / Q000379:methods; D004044:Dietary Proteins / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D005260:Female; D007273:Injections, Intramuscular / Q000662:veterinary; D007774:Lactation / Q000378:metabolism / Q000502:physiology; D008098:Litter Size; D008239:Lysine / Q000008:administration & dosage; D010298:Parity; D011247:Pregnancy; D011897:Random Allocation; D012098:Reproduction / Q000187:drug effects*; D013025:Glycine max; D013552:Swine / Q000254:growth & development / Q000502:physiology*; D014801:Vitamin A / Q000494:pharmacology*; D014815:Vitamins / Q000494:pharmacology; D014886:Weaning; D003313:Zea mays
chemical_list: D004044:Dietary Proteins; D014815:Vitamins; D014801:Vitamin A; D008239:Lysine