Effect of intensified feeding of heifer calves on growth, pubertal age, calving age, milk yield, and economics

Abstract

The objective of this study was to determine if increasing the energy and protein intake of heifer calves would affect growth rates, age at puberty, age at calving, and first lactation milk yield. A second objective was to perform an economic analysis of this feeding program using feed costs, number of nonproductive days, and milk yield data. Holstein heifer calves born at the Michigan State Dairy Cattle Teaching and Research Center were randomly assigned to 1 of 2 dietary treatments (n=40/treatment) that continued from 2 d of age until weaning at 42 d of age. The conventional diet consisted of a standard milk replacer [21.5% crude protein (CP), 21.5% fat] fed at 1.2% of body weight (BW) on a dry matter basis and starter grain (19.9% CP) to attain 0.45 kg of daily gain. The intensive diet consisted of a high-protein milk replacer (30.6% CP, 16.1% fat) fed at 2.1% of BW on a dry matter basis and starter grain (24.3% CP) to achieve 0.68 kg of daily gain. Calves were gradually weaned from milk replacer by decreasing the amount offered for 5 and 12 d before weaning for the conventional and intensive diets, respectively. All calves were completely weaned at 42 d of age and kept in hutches to monitor individual starter consumption in the early postweaning period. Starting from 8 wk of age, heifers on both treatments were fed and managed similarly for the duration of the study. Body weight and skeletal measurements were taken weekly until 8 wk of age, and once every 4 wk thereafter until calving. Calves consuming the intensive diet were heavier, taller, and wider at weaning. The difference in withers height and hip width was carried over into the early post-weaning period, but a BW difference was no longer evident by 12 wk of age. Calves fed the intensive diet were younger and lighter at the onset of puberty. Heifers fed the high-energy and protein diet were 15 d younger at conception and 14 d younger at calving than heifers fed the conventional diet. Body weight after calving, daily gain during gestation, withers height at calving, body condition score at calving, calving difficulty score, and calf BW were not different. Energy-corrected, age-uncorrected 305-d milk yield was not different, averaging 9,778 kg and 10,069 kg for heifers fed the conventional and intensive diets, respectively. However, removing genetic variation in milk using parent average values as a covariate resulted in a tendency for greater milk from heifers fed the intensive diet. Preweaning costs were higher for heifers fed the intensive diet. However, total costs measured through first lactation were not different. Intensified feeding of calves can be used to decrease age at first calving without negatively affecting milk yield or economics.

Relationship of post-weaning growth and age at puberty in crossbred beef heifers

“…The puberty weights obtained in this experiment are close to those reported by Samadi et al (2014), in which the authors found values of approximately 357 kg in Brahman heifers. Rincker et al (2011) subjected dairy heifers at an ADG of 0.95 kg during 180 days before the date predicted for puberty and observed puberty at 270 days. The accumulated weight gain at eleven months of age from the different genotypes had not been sufficient to show their development potential in body weight.…”

Heifer fertility and carry over consequences for life time production in dairy and beef cattle

“…The animals with the fastest growth rate produced lower 305-day milk yields in their first lactation compared with the slowest growth (9387 v. 9873 kg). Another trial by Davis Rincker et al (2011) found that pre-weaned heifers provided with a higher energy and protein diet did not alter their energy-corrected, ageuncorrected 305-day milk yield in comparison with those fed a conventional diet (averaging 10 069 and 9778 kg, respectively) although this difference became significant when the genetic values of the heifers were taken into account. Similarly, Soberon et al (2012) reported that for every 1 kg increase in ADG during the pre-weaning period, first lactation milk yield increased by 850 and 1113 kg in two different herds studied, showing a consistent positive effect of good early growth on subsequent milk production.…”

“…Feeding whole milk or milk replacer to support rapid pre-weaning growth rates enables heifers to achieve breeding size earlier. For example, calves with an ADG of 0.8 kg/day pre-weaning calved 27.5 days earlier than calves fed for gains of 0.55 kg/day (RaethKnight et al, 2009) while heifers fed for a pre-weaning ADG of 0.64 kg/day conceived and calved at a younger age when bred at the same BW as calves with growth rates of 0.44 kg/day (Davis Rincker et al, 2011). Shamay et al (2005) fed more milk pre-weaning and compared whole milk with milk replacer.…”

A Study of Dairy Heifer Rearing Practices from Birth to Weaning and Their Associated Costs on UK Dairy Farms

“…The decision to feed a restricted or enhanced feeding programme not only has financial implications, but also affects feed efficiency and growth [8]. Studies examining intensified feeding programmes have found that heifers attain puberty, conceive and calve earlier, and produce more milk during their first lactation than heifers fed conventional feeding programmes [9]. Heinrichs and Heinrichs [10] also showed that a 1 kg increase in dry matter intake (DMI) at weaning produced a 286.7 kg increase in first lactation milk yield and that the age at which calves began to consume >900 g/day was associated with an increased lifetime production of milk and milk constituents.…”