Abstract
Simple SummaryThe nutrients requirements of dairy cattle is the most used system to formulate dairy cattle diets. However, these guidelines were developed based on research using mostly purebred Holstein in temperate conditions and did not determine nutrient requirements of crossbred Holstein × Gyr or Gyr animals raised in a tropical environment. Studies conducted in tropical conditions demonstrated that breed largely affected the nutrient requirements of crossbred and Gyr cattle, which limits the use of this system. Our objective was to evaluate the effects of two feeding levels and three breed compositions on nutrient intake, digestibility, performance, and methane emissions of prepubertal (10-month-old) dairy heifers. We observed that feeding diets to allow gains of 400 and 800 g/day resulted in greater daily gain than the formulated, overestimating the nutritional requirements of the heifers. Overall, breed composition did not affect dry matter intake, but it did result in differences in nutrients digestibility coefficients and feed efficiency. Feeding prepubertal heifers above maintenance requirements was the main driver in reducing CH4 intensity in confinement conditions.The dairy Nutrients Requirements of Cattle (NRC) was developed using data from purebred Holsteins and it might not accurately predict the performance of crossbred cattle. Our objectives were to evaluate the effects of two feeding levels (FLs) and three breed compositions (BCs) on nutrient intake, digestibility, performance, and methane (CH4) emissions of prepubertal dairy heifers. We used thirty-six heifers from three BCs: purebred Holstein (H), purebred Gyr (G), and F1 Holstein × Gyr (HG). Each BC had 12 animals and the experiment was designed as twelve incomplete three by three Latin squares, in a factorial arrangement three by two, with three BCs and two FLs (400 and 800 g/day). Total tract nutrient digestibility was determined using total fecal collection and DMI was individually measured. The data were analyzed using the PROC MIXED in SAS. Dry matter intake of all nutrients increased from the medium to high feeding level and the nutrients digestibility coefficients did differ among BCs. Achieved body weight gain in the medium FL treatment was greater than those predicted using the NRC, suggesting that crossbred and Gyr heifers have similar performance to Holsteins. Breed composition does not influence body weight gain of confined dairy heifers, but Holstein heifers fed a medium FL had higher feed efficiency and reduced CH4 emissions intensity.
Highlights
The first experiments that focused on breeding Zebu cattle (Bos indicus) with Holstein breed (Bos Taurus) were published in 1940 and aimed to improve milk production, fertility, and rusticity of dairy animals in tropical countries [1]
This crossbred is the main basis of the Girolando (Holstein × Gyr) genotype and, due to the good adaptability and milk production, this cross has been widely used in tropical conditions nowadays [2]
We aimed to evaluate the effects of performance level and breed composition on nutrient intake, digestibility, performance, and methane emissions of prepubertal dairy heifers of three breed compositions (BCs) fed at two different feeding levels (FLs)
Summary
The first experiments that focused on breeding Zebu cattle (Bos indicus) with Holstein breed (Bos Taurus) were published in 1940 and aimed to improve milk production, fertility, and rusticity of dairy animals in tropical countries [1]. This crossbred is the main basis of the Girolando (Holstein × Gyr) genotype and, due to the good adaptability and milk production, this cross has been widely used in tropical conditions nowadays [2]. An intensification of on-farm data collection of this crossbred should be considered to fill this gap regarding intake and utilization of nutrients of Girolando raised in tropical conditions since these cows produce around 80% of the milk in Brazil [4]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call