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dc.contributor.authorByrne, C.J.
dc.contributor.authorFair, S.
dc.contributor.authorEnglish, A.M.
dc.contributor.authorCirot, M.
dc.contributor.authorStaub, C.
dc.contributor.authorLonergan, P.
dc.contributor.authorKenny, D.A.
dc.identifier.citationC.J. Byrne, S. Fair, A.M. English, M. Cirot, C. Staub, P. Lonergan, D.A. Kenny, Plane of nutrition before and after 6 months of age in Holstein-Friesian bulls: I. Effects on performance, body composition, age at puberty, and postpubertal semen production, Journal of Dairy Science, Volume 101, Issue 4, 2018, Pages 3447-3459, ISSN 0022-0302,
dc.description.abstractABSTRACTThe aim of this study was to examine the effect of plane of nutrition (1) during the first 6 mo of life and (2) from 6 mo of age to puberty on early growth characteristics, age at puberty, and postpubertal semen production in Holstein-Friesian bulls. Holstein-Friesian bull calves (n = 83) with a mean (standard deviation) age and body weight of 17 (4.4) d and 52 (6.2) kg, respectively, were assigned to a high (Hi) or low (Lo) plane of nutrition for the first 6 mo of life. The Hi and Lo calves received 1,200 and 450 g of milk replacer, respectively; Hi calves were fed concentrate ad libitum and Lo were fed a maximum of 1 kg concentrate daily, and concentrate allowances remained the same after weaning. At 24 wk of age, bulls were reassigned within treatment to either remain on the same diet or to switch to the opposite diet until puberty, resulting in 4 treatment groups: Hi-Hi, Hi-Lo, Lo-Lo, and Lo-Hi. After puberty, all bulls were fed a moderate plane of nutrition until 60 wk of age; thereafter, the diet was ad libitum concentrates until slaughter at 72 wk of age. Bulls were weighed weekly before weaning and every 2 wk after weaning. Scrotal circumference (SC) was measured every 2 wk, beginning at 15 wk of age. Beginning at a SC of 24 cm, electro-ejaculation was carried out every 2 wk to establish the onset of puberty. Semen collection continued monthly after puberty. Thermal images of the scrotum were taken monthly from 28 to 36 wk of age. Scrotal skin thickness (SST) was measured monthly (from 16 wk of age to puberty) using a digital calipers. Bulls on the Hi diet had a higher scrotal temperature and SST at each time point than those on the Lo diet. Average daily gain (ADG) was greatest in Hi-Hi bulls, with Hi-Lo and Lo-Hi having similar ADG but both being greater than Lo-Lo. Bulls on the Hi diet pre-6 mo of age were younger at puberty, regardless of diet offered post-6 mo of age. Bulls offered a Hi diet post-6 mo were heavier at puberty. Neither scrotal temperature nor dietary treatment affected postpubertal semen production variables. In conclusion, a high plane of nutrition during the first 6 mo of age hastened the onset of puberty and the availability of saleable semen, regardless of plane of nutrition post-6 mo of age.en_US
dc.relation.ispartofseriesJournal of Dairy Science;Vol 101
dc.rights© 2018 American Dairy Science Association®.
dc.rightsAttribution-NonCommercial-ShareAlike 4.0 International*
dc.subjectsemen qualityen_US
dc.subjectage at pubertyen_US
dc.titlePlane of nutrition before and after 6 months of age in Holstein-Friesian bulls: I. Effects on performance, body composition, age at puberty, and postpubertal semen productionen_US
dc.contributor.sponsorIrish Department of Agriculture, Food and the Marineen_US
dc.source.journaltitleJournal of Dairy Science

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