Ractopamine hydrochloride improves growth performance and carcass composition in immunocastrated boars, intact boars, and gilts

The β-agonist ractopamine is a dietary ingredient that improves growth and increases the lean mass with little change in fat mass in gilts and barrows. Limited data in boars indicate that dietary ractopamine may increase lean tissue and decrease fat deposition, whereas there are no data for immunoca...

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Vydáno v:	Journal of animal science Ročník 87; číslo 11; s. 3536 - 3543
Hlavní autoři:	Rikard-Bell, C, Curtis, M.A, van Barneveld, R.J, Mullan, B.P, Edwards, A.C, Gannon, N.J, Henman, D.J, Hughes, P.E, Dunshea, F.R
Médium:	Journal Article
Jazyk:	angličtina
Vydáno:	Champaign, IL American Society of Animal Science 01.11.2009 Am Soc Animal Sci Oxford University Press
Témata:	Animal productions Animal sciences Animals backfat barrows beta-adrenergic agonists Biological and medical sciences boars body composition body weight Breeding of animals carcass composition carcass weight Castration Castration - veterinary dosage dose response drug effects Feed conversion feed intake Female Food Additives Food Additives - pharmacology Food industries Fundamental and applied biological sciences. Psychology gender differences Genotype & phenotype gilts growth & development Growth Substances Growth Substances - pharmacology Hogs immunologic techniques lean body mass liveweight gain Male Meat and meat product industries medicated feeds pharmacology Phenethylamines Phenethylamines - pharmacology physiology Sex Factors Sus scrofa Sus scrofa - growth & development Sus scrofa - physiology Terrestrial animal productions testes thickness Vertebrates veterinary Weight Gain Weight Gain - drug effects Farming animal Ractopamine Growth Meat product Carcass Body composition Pig boar Vertebrata Meat animals Mammalia Chemical composition Artiodactyla immunocastration Performance Ungulata
ISSN:	0021-8812, 1525-3163, 1525-3163
On-line přístup:	Získat plný text
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Shrnutí:	The β-agonist ractopamine is a dietary ingredient that improves growth and increases the lean mass with little change in fat mass in gilts and barrows. Limited data in boars indicate that dietary ractopamine may increase lean tissue and decrease fat deposition, whereas there are no data for immunocastrated boars. The aims of this investigation were 1) to assess whether the growth performance of all sexes could be maintained over 31 d by using a step-up dietary ractopamine feeding program of 5 mg/kg of ractopamine for the first 14 d, then increasing the dose to 10 mg/kg for a further 17 d, and 2) to determine if dietary ractopamine would increase lean mass in all sexes and decrease fat mass in boars and immunocastrated boars. The study involved 286 pigs randomized and proportionally allocated by breed into 24 groups of 11 or 12 pigs at 17 wk of age, with equal groups of boars, immunocastrated boars, and gilts. Dietary ractopamine decreased (P = 0.005) ADFI during the first 2 wk, particularly in the intact and immunocastrated boars, with the reduction in ADFI being maintained in the immunocastrated boars after the increment in dietary ractopamine. Daily BW gain was not altered by dietary ractopamine during the first 2 wk, but was increased (P < 0.001) after the increment in dietary ractopamine. Dietary ractopamine decreased (P [less-than or equal to] 0.033) feed conversion ratio in all sexes with the response being greater after the increase in dietary ractopamine. Carcass weight was increased (P < 0.001) by dietary ractopamine in all sexes, whereas back fat tended (P = 0.076) to be reduced in the immunocastrated boars. Dietary ractopamine increased (P = 0.018) lean tissue mass by 4.0, 4.8, and 6.5 kg in the intact boars, gilts, and immunocastrated boars, respectively. In the entire and immunocastrated boars, the increase in lean tissue was accompanied with a decrease (P = 0.004) in fat mass. There was little effect of dietary ractopamine on fat mass in gilts. However, carcass percent fat was decreased (P = 0.004) and percent lean increased (P = 0.006) in all sexes. Immunocastration caused a decrease in lean tissue mass and an increase in fat mass and an increase in ADFI in the last one-half of the study. Dietary ractopamine may decrease fat mass in intact and immunocastrated boars and offers an excellent means of maximizing the effects of immunocastration and minimizing the increase in fat mass sometimes observed in immunocastrated boars.
Bibliografie:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 content type line 23
ISSN:	0021-8812 1525-3163 1525-3163
DOI:	10.2527/jas.2009-2002