Effects of a Grain Source (Corn Versus Barley) and Starter Protein Content on Performance, Ruminal Fermentation, and Blood Metabolites in Holstein Dairy Calves.

Mehdi Kazemi-Bonchenari,Mehdi Mirzaei,Mahdi Khodaei-Motlagh,Mehdi Hosseinyazdi,Mohammad Hossein Moradi,Adel Pezeshki

doi:10.3390/ani10101722

Mehdi Kazemi-Bonchenari, Mehdi Mirzaei + Show 4 more

Open Access

https://doi.org/10.3390/ani10101722

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Abstract

Simple SummaryDairy calf producers are concerned about feeding barley grain to dairy calves due to its rapid starch fermentation rate in the rumen compared to corn grain. Therefore, corn grain is still the main energy source in starter diets in dairy calves. However, some studies on bull and dairy calves indicated that there are some potentials for including barley grain in their diets with positively influencing the performance and feed efficiency. Optimum protein content in starter diet is an important factor influencing the animal growth response to grain source. This may be due to adequate nitrogen availability rate when starch is rapidly degraded in the rumen. Therefore, we hypothesized that dairy calves may produce different growth response to grain source with various ruminal starch degradation rate (high degradation rate in barley grain vs. low degradation rate in corn grain) when fed with starters with different protein content. Here we show that the average daily gain, feed efficiency, and ruminal fermentation profile were improved in dairy calves fed with barley grain. Furthermore, when dairy calves receive high protein content in their starter diet, barley grain improves growth performance in comparison with corn grain. Our study suggests that barley grain can be included in dairy calf starter diet when a starter with higher protein content is provided. The effects of a grain source (corn grain (CG) vs. barley grain (BG)) and starter protein content (19% vs. 22% CP, dry matter basis) on growth performance, digestibility, ruminal fermentation, and blood metabolites were evaluated in Holstein dairy calves. Forty 3-day-old female calves with a starting body weight of 39.3 kg were subjected to four treatments in a completely randomized design with two by two factorial arrangements. Treatments were: (1) CG + 19% CP (CG-19CP); (2) CG + 22% CP (CG-22CP); (3) BG + 19% CP (BG-19CP); and (4) BG + 22% CP (BG-22CP). All calves were weaned at 59 days of age and remained in the study until 73 days of age. Starter and total DM intake were not affected by grain source and dietary protein content (p > 0.05). The average daily gain and feed efficiency were improved, and ruminal total short-chain fatty acid, propionate, and butyrate concentrations were increased in BG calves compared to CG calves (p < 0.05). The ruminal concentrations of ammonia nitrogen (d 71; p = 0.02) and acetate (d 35; p = 0.02) were increased in CG fed calves compared to BG. The greatest wither height (p = 0.03) and blood insulin concentration (p = 0.03) were seen in BG-22CP treatment. In conclusion, BG has marginal benefit in the height of calves when fed with diet containing 22% CP which may be recommendable in replacement heifer rearing programs.

Highlights

Grains are the main source of energy in dairy calves’ starter diet
Among different starch sources available as feedstuff in dairy calves’ diet, there is a tendency to feed calves with corn grain (CG) rather than other high-starch grains [3,4]. This is likely due to the slower starch degradation rate of CG compared to other high-starch grain sources such as barley grain (BG) which is related to various starch granule structures and shapes, as well as its coverage/linkage with protein or lipid components [5]
This can be critical for dairy calves when they are fed with high-starch grains as they are more susceptible to ruminal pH drop than mature ruminants [8]

Summary

Introduction

Grains are the main source of energy in dairy calves’ starter diet. The energy content of the grains is positively correlated with starch content [1]. Among different starch sources available as feedstuff in dairy calves’ diet, there is a tendency to feed calves with corn grain (CG) rather than other high-starch grains [3,4]. The faster ruminal starch degradation rate of BG compared with CG when the ground grains are fed creates some concerns for inducing subacute ruminal acidosis [3]. This can be critical for dairy calves when they are fed with high-starch grains as they are more susceptible to ruminal pH drop than mature ruminants [8]. Optimum dietary particle size [12], adequate level of forage in the diet [13,14], and proper fermentation rate of starch [15] are major factors influencing the feeding efficiency of high-starch grains in dairy calves

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