As Nellore cattle are the most used breed in Brazil, a study was conducted to optimise the requirements are for macrominerals and trace elements. This information can be used to optimise performance in these type of cows.
Minerals play a vital role in livestock animals. In beef cattle, most research in the requirements has been done in using breeds that are uncommon in Brazil, such as Angus and Hereford cattle. A research team from the Universidade Federal de Viçosa in Brazil therefore set up a study with Nellore cattle to determine nutrient requirements for this breed. Nellore is the most utilised cattle breed in Brazil.
In the study 87 Nellore animals were used to estimate net requirements for the maintenance and growth of beef cattle as well as the retention coefficients of 13 minerals: macrominerals (Ca, P, Mg, K, Na, and S) and trace elements (Cu, Fe, Mn, Se, Zn, Co, and Cr). The study consisted of 2 experiments: 1 with bulls and 1 with heifers and steers,
The researchers hypothesised that knowledge of the net requirements for maintenance and growth as well as the true retention coefficient will improve the precision of setting requirements for all minerals. The net requirements for maintenance and the true retention coefficient were estimated by using the regression between apparent retention and intake for each mineral.
Average daily gain (ADG) in the study was between 0 and 1.95 kg/d, and dry matter intake (DMI) between 1.18 and 11.1 kg/d.
It was further shown that the net requirement for maintenance (μg/kg BW) and retention coefficients (%) were 163 and 85 for Cu, 2,097 and 53 for Fe, 32.3 and 24 for Mn, 3.72 and 48 for Se, 669 and 0.80 for Zn, 18.4 and 86 for Co, and 22.9 and 78 for Cr. The dietary requirements of macrominerals (g/kg DMI) were 5.12 for Ca, 2.38 for P, 0.96 for Mg, 2.40 for K, 0.79 for Na, and 1.47 for S.
The researchers conclude that the use of the true retention coefficient improves the estimates of dietary requirements for Na, K, Mg, and S due to the considerable excretion of these minerals in urine. Also, the use of the net requirements for maintenance and growth and the true retention coefficient for the majority of the trace minerals resulted in different estimates than those obtained from the literature. This is the first study using Nellore cattle to estimate mineral requirements; considering that Nellore cattle are the most common breed in Brazil and that Brazil is a major beef producer globally, this knowledge can help producers to improve animal performance by supplying the correct amount of minerals.
[Source: PLOS ONE]
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