Reproductive traits as cause of variation in milk yield

Authors

  • Maria Armênia Ramalho de Freitas Instituto de Zootecnia, Estação Experimental de Zootecnia de Ribeirão Preto, SP
  • Raysildo Barbosa Lobo Universidade de São Paulo, Faculdade de Medicina, Ribeirão Preto, SP
  • Vera Lúcia Cardoso Instituto de Zootecnia, Estação Experimental de Zootecnia de Ribeirão Preto, SP

Abstract

Production data recorded over a period of 15 years for Holstein cows were analyzed in order to establish the effect of gestation length, calving interval before lactation, and days open during the current lactation on milk and butterfat yield. The herd studied is maintained in a region of the State of São Paulo, Brazil, which, during the period analyzed, had a mean yearly temperature of 200C, mean yearly rainfall of 1,230 mm, and less than 85% relative humidity. Farm management is satisfactory, with plentiful feed based on silage and green fodder, and supplementation provided according to yield. Nonadjusted means of milk yield, fat yield and fat percentage for 2,987 observations over 318 lactation days with twice daily milking were: 4,456 ±28kg (CV =34%); 165.0± 1.1 kg (CV =32%) and 3.60 ±0.01 (CV = 11%), respectively. The reproductive traits analyzed showed the following mean values and standard errors (in days): 278 ± 0.6, 438 ± 2.1 and 160 ±20 for gestation length (GL), calving interval (Cl) and days open (DO), respectively. Analysis of variance by least squares method included the following effects in addition to the previously mentioned reproductive traits: progeny sex, month and year of calving, cow age and lactation length (linear, quadratic and cubic effects). All effects included in the model were significant, except progeny sex and gestation length. The effect of Cl on milk and fat yield was best described by linear and quadratic equations, whereas the effect of DO on milk yield was best described by quadratic and cubic equations. In general, yield increased with Cl preceding lactation up to about 400 days and with number of days open during the current lactation up to 150 days, with no definite tendency shown after this period.

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Published

2014-01-29

Issue

Section

ANIMAL REPRODUCTION

How to Cite

Reproductive traits as cause of variation in milk yield. (2014). Bulletin of Animal Husbandry, 42(1), 131-140. http://35.198.24.243/index.php/bia/article/view/635

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