Protein requirements for pregnancy in dairy cows

• Autor(a) principal: Provazi, Felipe de Paiva
• Data de Publicação: 2019
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: https://locus.ufv.br//handle/123456789/29381
• topic: Crescimento fetal; Feto; Gestação; Exigências Nutricionais dos Animais

The data that compose the protein requirements for the pregnancy are scarce. The objective of the present study was to estimate the nutritional requirements of protein for maintenance, weight gain, and pregnancy of crossbred Holstein × Gir dairy cows. Sixty-two cows were used. We used the comparative slaughter technique to estimate the requirements for pregnancy. Six animals were used as reference group and they were slaughtered at the beginning of the experiment to estimate initial empty body weight and initial body composition. The remaining cows were divided into two groups: pregnant (n = 44) and non-pregnant (n =12). Pregnant and non-pregnant cows received two different diets: maintenance (MA) and ad libitum (AD). Pregnant cows were slaughtered at four different days of gestation (DG): 139, 199, 241, and 268. The non-pregnant cows were slaughtered at 199, 241, and 268 days of gestation. The pregnant cows had the gravid uterus collected and weight. The gravid uterus was dissected into fetus, placenta, uterus, and fetal fluids. The metabolizable protein for requirements of maintenance was 3.60 g/EBW 0.75 /d. The adjusted equation to estimate the net protein requirements for gain (NE g ) was: NE g (g/day) = 0.592554 × (EBW open-0.268 ). The efficiency of use of metabolizable protein for gain (k g ) was 35.30%. The equation to predict the net protein requirements for gain (NP g) was: NP g (g/day) = 0.0001767 × exp (0.02666 × DG) . The efficiency of use of metabolizable protein for pregnancy (k gest was 65.30%. Differences are observed when comparing our values for MP m , NP g , NP gest , K g and K gest data with other systems and studies. These differences may be due to differences in the calculation method and breed animals used. We suggest the equations and efficiency factors proposed in this study for accurate protein requirement estimates for pregnant dairy cows. Keywords: Fetal growth. Fetus. Gestation