Determination of energy and protein requirements for crossbred Holstein × Gyr preweaned dairy calves

Abstract

The objective was to quantify the energy and protein nutritional requirements of Holstein × Gyr crossbred preweaned dairy calves until 64 d of age. Thirty-nine Holstein × Gyr crossbred male calves with an average initial live weight (mean ± SEM; for all next values) of 36 ± 1.0 kg were used. Five calves were slaughtered at 4 d of life to estimate the animals' initial body composition (reference group). The remaining 34 calves were distributed in a completely randomized design in a 3 × 2 factorial arrangement consisting of 3 levels of milk (2, 4, or 8 L/d) and 2 levels of starter feed (presence or absence in diet). At 15 and 45 d of life, 4 animals from each treatment were subjected to digestibility trials with total collection of feces (for 72 h) and urine (for 24 h). At 64 d of age, all animals were slaughtered, their gastro-intestinal tract was washed to determine the empty body weight (EBW; kg), and their body tissues were sampled for subsequent analyses. The net energy requirement for maintenance was estimated using an exponential regression between metabolizable energy intake and heat production (both in Mcal/EBW per d) and was 74.3 ± 5.7 kcal/EBW per d, and was not affected by inclusion of starter feed in the diet. The metabolizable energy requirement for maintenance was determined at the point of zero energy retention in the body and was 105.2 ± 5.8 kcal/EBW per d. The net energy for gain was estimated using the EBW and the empty body gain (EBG; kg/d) as 0.0882 ± 0.0028 × EBW × EBG. The metabolizable energy efficiency for gain (k) of the milk was 57.4 ± 3.45%, and the k of the starter feed was 39.3 ± 2.09%. The metabolizable protein requirement for maintenance was 3.52 ± 0.34 g/BW per d. The net protein required for each kilogram gained was estimated as 119.1 ± 32.9 × EBW. The metabolizable protein efficiency for gain was 77 ± 8.5% and was not affected by inclusion of starter feed in the diet. In conclusion, the energy efficiency for gain of milk is higher than that of starter and the net protein required per unit protein gain increases with empty body weight.

Energy requirements for pregnant dairy cows

“…Efficiency of use of metabolizable energy for pregnancy was estimated by the iterative method. The obtained value for k preg was 14.1 ± 0.41%, which is very close to values obtained by Ferrell et al [1], 14%; Lage [40], 12.5% and BR-CORTE [4], 12%. The NRC [6] uses k preg suggested by Ferrell et al [1].…”

“…Lage [ 40 ] found NE preg , represented by retained energy in gravid uterus and mammary gland for Holstein × Gyr cows of 2.70, 2.71, and 2.88 Mcal/day at 180, 210 and 240 days of pregnancy, respectively. Net energy requirements obtained by Lage [ 39 ] are closer to NRC [ 6 ] when compared to our values.…”

“…Calf body weight (35 kg) was obtained according to average weight of Holstein × Gyr calves from Silva et al [40] and Azevedo et al [41]. The NRC [6] uses a linear regression equation to estimate NE preg considering days of pregnancy and calf body weight, and the fetus accounts for approximately 80% of uterine dry weight [3].…”

The Potential of Using Temperate–Tropical Crossbreds and Agricultural by-Products, Associated with Heat Stress Management for Dairy Production in the Tropics: A Review

“…The breed’s performance in Southeast Asian countries ranges from 1710 to 1978 kg of milk/lactation [ 36 , 54 ]. Another well-established breed is the Holstein × Gyr breed, where several requirement and feed efficiency studies have been conducted in recent years [ 55 , 56 , 57 ]. The breed was observed to produce an average milk yield of 5118 and 5211 kg/lactation of 1/2 and 7/8 Holstein composition, respectively [ 38 ].…”

Influence of starter crude protein content on growth and body composition of dairy calves in an enhanced early nutrition program

“…Blome et al (2003) and Bartlett et al (2006) demonstrated that increasing dietary CP in milk replacer increased lean tissue gain and decreased fat content of empty body (EB) gain. However, few studies have determined changes of body composition and EB gain in calves fed both starter feed and milk or milk replacer (Meyer, 2005;Silva et al, 2017).…”