COVER STOR ▶▶▶Y


Mineral requirements for calves in the tropics


Minerals are extremely important in animal nutrition. However, there is lack of information regarding mineral requirements for pre- weaned dairy calves raised under tropical conditions. Here we take a closer look at what Holstein and Gyr crossbred calves need in terms of macrominerals.


BY PROF MARCOS INÁCIO MARCONDES, UNIVERSIDADE FEDERAL DE VIÇOSA, BRAZIL


M


Mineral EBW 0.50 Ca


40


P 40 K 40 Mg


40 70


P 70 K 70 Mg


70 100


P 100 K 100 Mg


100 Na 100


6.61 4.78 1.47 1.36


Na 40 3.58 Ca


6.7


5.29 2.15 1.7


Na 70 4.24 Ca


6.95 5.81 2.83 2.04 4.95


12.53 8.81 2


12.18 9.26 2.67 2.58 6.65


12.17 9.74 3.35 2.9


7.28


inerals play essential functions in the body (i.e., structural, physiological, catalytic, regulatory, and immune response), although they are found in small concentrations compared with


Table 1 – Dietary requirements (g/d) of Ca, P, K, Mg, and Na.


EBG


Present study BR-CORTE (2016) 1.00


0.50


12.07 6.38 3.29


2.25 1.24 6.1


2.22


10.56 6.89 4.76 1.75 2.73


10.09 7.43 6.24 2.26 3.25


1.00


23.18 11.91 4.52 1.76 3.72


19.45 12.3 5.95 2.27 4.21 17.8


12.78 7.4


2.78 4.72


NRC (2001) 0.50


12.13 8.23 2.83 2.18 1.56


11.58 8.4


4.25 2.77 2.12


11.58 8.83 5.67 3.37 2.68


1.00


23.28 13.64 3.76 3.56 2.38


21.44 13.18 5.18 4.16 2.94


20.69 13.25 6.6


4.75 3.5


Based on the estimates proposed by this study, BR-CORTE (2016)), and NRC (2001)) for different empty BW (EBW; kg) and empty body gain (EBG; kg/d).


20 ▶DAIRY GLOBAL | Volume 6, No. 2, 2019


other nutrients such as fat and protein. Therefore, a deficien- cy in minerals can compromise the productivity and repro- ductive performance of livestock. However, there is not a lot of information available regarding the mineral requirements for pre-weaned dairy calves raised under tropical conditions. In practice, diet formulation is hence based on mineral re- quirements reported by international councils, where NRC (2001) is the most commonly used publication for formulat- ing diets for growing dairy calves. The NRC (2001) suggests fixed recommendations of mineral concentrations in the diet of pre-weaned dairy calves regardless of bodyweight, genetic makeup, or animal performance. The only nutrient require- ments developed for cattle living under tropical conditions are those of BR-CORTE (2016). However, this system only esti- mates the nutrients for beef breeds and estimates the net mineral requirements for growing Zebu calves up to 180 days of age and not for calves below 90 kg.


Holstein×Gyr crossbred calves Diet formulation, based on assumptions and old studies from the 1950s, 70s and 80s, is not recommended and never leads to the best possible diet. In addition, dairy cattle have under- gone intense genetic selection over the last decade, which


PHOTO: CRV LAGOA


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36