ABSTRACT
The objectives of this study were: (1) to evaluate feed efficiency indexes and their relationships with body measurements and blood and ruminal metabolites in the pre-weaning period; (2) to determine if such measurements can be used as feed-efficiency markers during the pre-weaning period. Holstein-Gyr heifer calves (n = 36), enrolled between 4 and 12 weeks of age, were classified into two residual feed intake (RFI) and residual body weight gain (RG) groups: high efficiency (HE; RFI, n = 10; and RG, n = 9), and low efficiency (LE; RFI, n = 10; and RG, n = 8). Calves were fed whole milk (6 L/day) and solid feed ad libitum. Body developments were measured weekly and feed intake (milk and solid feed) daily during the whole period. Blood samples were collected at 12 weeks of age and analyzed for glucose, insulin and ß-hydroxybutyrate (BHB). Samples of ruminal content were collected on the same day and analyzed for pH, NH3-N, and volatile fatty acids (VFA). Among the growth characteristics, only the initial hip width differed between the RFI groups, and withers height differed between the RG groups. Concentration of BHB was greater and glucose: insulin ratios tended to be greater in LE-RG animals. Butyric acid proportions were similar among RFI groups, but tended to be greater for HE-RG than for LE-RG. Overall, correlation coefficients between RFI or RG and blood, rumen, or morphometric markers were low. Thus, it is unlikely that measurements of metabolic indicators, per se, will be useful in the early identification of more efficient animals. Understanding the underlying physiological basis for improved feed efficiency in dairy heifers requires further investigation.
ABSTRACT
The aim of this study was to evaluate the consumption, performance, feed efficiency, glucose concentration, and the cost per kilogram of weight gain of crossbred Holstein-Gyr heifers (n = 33) subjected to one of the three waste milk step-down strategies: 6L-30d/4L-60d/2L-90d (T1), 6L-45d/4L-60d/2L-90d (T2), and 8L-30d/6L-60d/3L-90d (T3). Heifers were weaned at the age of 91 days. Water and starter were provided ad libitum. The average waste milk intake was higher in T3 than in T1 and T2 strategies until 30 days and between 60 and 90 days. The starter intake did not differ among the strategies until 45 days, but it was higher in strategy T1 than in strategy T3 between 60 and 90 days. The waste milk step-down strategy did not influence the total dry matter intake, average daily gain, body weight, and feed efficiency. Glucose concentrations in plasma varied within a range that could be considered normal and were similar among the treatments. The average cost per kilogram of weight gain was the lowest in strategy T1 (US$3.0) compared to that in the other strategies (T2, US$3.2, and T3, US$3.6). The 6L-30d/4L-60d/2L-90d waste milk step-down strategy was the most effective, since it increased the starter intake, led to normal glucose concentrations in plasma, and caused similar weight gain compared with the other strategies; however, it had a lower cost per kilogram.
Subject(s)
Animal Feed/analysis , Animal Husbandry , Cattle/physiology , Milk , Animal Husbandry/economics , Animal Nutritional Physiological Phenomena , Animals , Animals, Newborn/physiology , Body Weight , Brazil , Dairying , Diet/veterinary , Female , Tropical Climate , Weaning , Weight GainABSTRACT
Nos últimos anos, além do histórico aumento dos custos de produção, a pecuária leiteira nacional vem lidando com novos desafios,como a crescente percepção dos consumidores quanto à segurança alimentar, bem-estar animal e impactos ambientais da agropecuária. Nesse cenário de margens de lucro reduzidas, só existe um caminho a ser seguido: o aumento da eficiência dos sistemas de produção de leite.
Subject(s)
Animals , Animal Husbandry/methods , Efficiency , Milk , Nutrition Programs , Technology/methods , Animal Welfare , Heart Rate , Environment , Thermography/veterinaryABSTRACT
Tecnologias inovadoras e biotecnologias contribuem significativamente para o avanço em pesquisa animal,permitindo a identificação da variabilidade animal e o desenvolvimento de produtos,processos e serviços para aplicação do conceito de pecuária de precisão nas fazendas leiteiras.
Subject(s)
Animals , Animal Husbandry/methods , Technological Development/analysis , Thermography/veterinary , Animal Welfare/organization & administration , Blood Circulation , Diagnosis , Pathology, Veterinary , Body Temperature Regulation , ThermographyABSTRACT
Tecnologias inovadoras e biotecnologias contribuem significativamente para o avanço em pesquisa animal,permitindo a identificação da variabilidade animal e o desenvolvimento de produtos,processos e serviços para aplicação do conceito de pecuária de precisão nas fazendas leiteiras.
Subject(s)
Animals , Thermography/veterinary , Technological Development/analysis , Animal Husbandry/methods , Animal Welfare/organization & administration , Body Temperature Regulation , Blood Circulation , Thermography , Diagnosis , Pathology, VeterinaryABSTRACT
Nos últimos anos, além do histórico aumento dos custos de produção, a pecuária leiteira nacional vem lidando com novos desafios,como a crescente percepção dos consumidores quanto à segurança alimentar, bem-estar animal e impactos ambientais da agropecuária. Nesse cenário de margens de lucro reduzidas, só existe um caminho a ser seguido: o aumento da eficiência dos sistemas de produção de leite.