RESUMEN

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.

RESUMEN

The objective of this study was to assess the control feasibility of Streptococcus agalactiae subclinical mastitis and its impact in reducing somatic cell counts (SCC) of bulk milk tank. During the lactation, 33 cows positive for Streptococcus agalactiae in microbiological culture were treated with three applications of intramammary antimicrobial containing 100.000 UI of penicillin and 150 mg of novobiocin, in an interval of 12 hours. Individual and bulk tank milk samples were collected for somatic cell count (SCC) analysis and milk yield was measured before and after treatment. Statistical analyses were performed with SAS System, version 9.2. All cows treated against S. agalactiae had microbiological cure and reduction of SCC, indicating the effectiveness of treatment. SCC in bulk tank was reduced from 829,000 to 513,000 cells/ml.

Asunto(s)

RESUMEN

The objective of this study was to assess the control feasibility of Streptococcus agalactiae subclinical mastitis and its impact in reducing somatic cell counts (SCC) of bulk milk tank. During the lactation, 33 cows positive for Streptococcus agalactiae in microbiological culture were treated with three applications of intramammary antimicrobial containing 100.000 UI of penicillin and 150 mg of novobiocin, in an interval of 12 hours. Individual and bulk tank milk samples were collected for somatic cell count (SCC) analysis and milk yield was measured before and after treatment. Statistical analyses were performed with SAS System, version 9.2. All cows treated against S. agalactiae had microbiological cure and reduction of SCC, indicating the effectiveness of treatment. SCC in bulk tank was reduced from 829,000 to 513,000 cells/ml.(AU)

Asunto(s)

RESUMEN

Durante o aleitamento a recomendação adotada mundialmente consiste no fornecimento da dieta líquida de modo restrito, em aproximadamente 10% do peso corporal (PC) do bezerro,com o objetivo de junto com o desaleitamento precoce, reduzir custos com a alimentação e incentivar o consumo precoce de concentrado.Entretanto, o fornecimento restrito durante a fase de aleitamento proporciona baixo ganho médio diário (GMD), riscos de doenças e comportamentos indicativos de fome crônica,reduzindo o bem-estar dos bezerros.

Asunto(s)