Supplementation of rangeland primiparous Bos indicus x Bos taurus beef heifers during lactation. 1. Effects on dam milk production and liveweight, bull calf growth, live carcass characteristics and metabolic hormone concentrations
| Autor: | V.E.A. Perry, Raymond J. Rodgers, M.J. Callaghan |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Male
animal diseases medicine.medical_treatment Fatty Acids Nonesterified Biology Blood Urea Nitrogen 03 medical and health sciences 0302 clinical medicine Animal science Food Animals Pregnancy Lactation Grazing medicine Animals Weaning Bull calf Animal Husbandry Small Animals Blood urea nitrogen 030219 obstetrics & reproductive medicine Equine Artificial insemination 0402 animal and dairy science 04 agricultural and veterinary sciences Animal Feed 040201 dairy & animal science Hormones Parity medicine.anatomical_structure Dietary Supplements Body Composition Cattle Female Animal Science and Zoology Dietary Proteins Rangeland Hormone |
| Zdroj: | Theriogenology. 152:69-82 |
| ISSN: | 0093-691X |
| DOI: | 10.1016/j.theriogenology.2020.04.030 |
| Popis: | The practice of feeding replacement-breeding bulls on high energy diets after weaning to meet liveweight (LW) and carcass expectations between 18 and 24 months of age negatively affects reproductive potential. This experiment reports upon the effects of an alternative management strategy aimed at improving calfhood nutrition in rangeland-reared bulls to enhance LW and live carcass characteristics at 2 years. Following artificial insemination (AI cohort; n = 26), or natural mating, subsequent to the addition of bulls at 39 d post-AI (NM cohort; n = 36), primiparous Santa Gertrudis heifers grazing rangeland pastures with bull calf progeny were allocated at parturition to receive either nil supplement (control; CON) or provided with unrestricted access to a pelleted vegetable protein meal-based supplement containing 35% CP (SUPP) until weaning at 199 ± (SD) 26 d. The mean estimated pellet consumption by SUPP heifers during lactation was 2.6 ± (SEM) 0.5 kg DM daily. Grazing diet quality measurements indicated nutritional restriction of CON heifers until at least 115 d of lactation. This was confirmed by lower blood urea nitrogen concentrations at 88 d (P 0.001) and greater mean NEFA (P 0.001) concentrations. Rainfall during mid-lactation subsequently improved grazing diet quality; thus the CON heifers experienced moderate nutritional restriction across lactation, but sufficient to reduce milk yield by 1.6 kg/d (P 0.001) and maternal LW at weaning by 18.4 kg (P 0.001). Bulls reared by SUPP heifers were 17.5 kg heavier at weaning (P = 0.001) and had elevated IGF-I and leptin concentrations between 4 and 4.5 months of age (P 0.05). Effects on metabolic hormones during calfhood were cohort specific, with greater concentrations of IGF-I confined to AISUPP bulls and NMSUPP bulls demonstrating greater concentrations of leptin. Bulls were amalgamated at weaning and grazed common pastures without supplementation until the experiment concluded at 675 d. Pre-weaning plane of nutrition did not affect the LW, carcass fat depth, IGF-I or leptin concentrations of bulls after weaning. Mean eye muscle area (EMA) was greater in SUPP compared to CON bulls (68.5 ± 0.9 cm |
| Databáze: | OpenAIRE |
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