471 Feed efficiency of Holstein and Jersey dairy cows in the tropics.

Ríos, Carolina; Reyes-Flores, C; Navedo-Guzmán, N; Curbelo-Rodríguez, Jaime E.; Ortiz-Colón, Guillermo

doi:10.1093/jas/sky404.563

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“…À medida que aumentou a idade das vacas na primeira lactação reduziu a chance de produzir leite com teor de proteína acima de 3,3%, o que pode ser explicado pelo efeito da raça dos animais. As vacas de primeira lactação, do presente estudo, com idade mais elevadas foram predominantemente da raça Holandesa, reconhecidas por serem mais tardias, frente a raça Jersey e suas cruzas e produzirem leite com menor teor de proteína (RIOS et al, 2018). Esse efeito, pode ser ainda mais significativo em fêmeas ao início de lactação, tendo em vista que o metabolismo de mobilização de reservas corporais e conversão em nutrientes no leite são bastante distintos entre as raças Holandês e Jersey (MITCHELL, 2016).…”

Section: Materials E Métodounclassified

Probabilidade de produção de leite com teores de gordura e proteína desejados pela indústria

Pacheco

Sudoski

Morais³

et al. 2020

Bol. Ind. Anim.

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The objective was to estimate the probability of dairy cows producing milk with fat and protein levels above the percentages desired by the industry, as well as the main factors that influence these levels. Milk samples of 78 first-lactation cows from 29 rural properties in the Planalto Norte Catarinense region were analyzed individually. The reference values for the analysis of fat and protein content were 4.0% and 3.3%, respectively. Logistic regression was used for analysis of the variables and the parameters were evaluated using odds ratios. Breed, age, gestation length, and grazing time are the variables that most influence the probability of producing milk with a protein content above 3.3%. Increasing milk production reduces the probability of obtaining milk with a fat content that allows the maximum bonus. Improvements in the cow's body condition increase the probability of obtaining milk with a fat content that meets the industry's requirements for maximum bonus.

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Section: Materials E Métodounclassified