# Impacts of feeding milk replacer containing 20% or 24% protein and fat on growth and feed efficiency of beef × dairy crossbred calves

## TL;DR

Feeding beef × dairy crossbred calves a higher-protein and -fat milk replacer improved their growth and feed efficiency without affecting digestion health.

## Contribution

This study provides new empirical evidence on optimal feeding strategies for beef × dairy crossbred calves using different milk replacer compositions.

## Key findings

- Feeding MR24 increased average daily gain by 23.4% during the preweaning period.
- MR24 improved feed efficiency by 9.80% over the 56-day experiment.
- MR24 had no negative impact on fecal scores or scouring incidence.

## Abstract

Summary: Best feeding practices have largely yet to be established for the increasing proportion of beef × dairy calves produced on dairy farms. Therefore, the current study sought to compare the effects of feeding milk replacers (MR) containing 20% (MR20) and 24% (MR24) crude protein (CP) and fat to beef × dairy calves. Forty calves received 1 of 2 MR treatments and calf starter (CS) starting from day 2 to 5 of age (day 1 of the experiment) until weaning 49 days later, at which point calves were offered solely CS until day 56. This study observed that the average daily gain (ADG) of crossbred calves receiving MR24 increased 23.4% and 23.6% during the preweaning and total experiment, respectively. Additionally, feeding MR24 to crossbred calves increased feed efficiency (gain/feed, kg/kg) by 9.80% during the entire 56-day period compared with MR20. Milk replacer treatment had no impact on fecal scores of beef × dairy crossbred calves during the preweaning period or entire experiment.

Summary: Best feeding practices have largely yet to be established for the increasing proportion of beef × dairy calves produced on dairy farms. Therefore, the current study sought to compare the effects of feeding milk replacers (MR) containing 20% (MR20) and 24% (MR24) crude protein (CP) and fat to beef × dairy calves. Forty calves received 1 of 2 MR treatments and calf starter (CS) starting from day 2 to 5 of age (day 1 of the experiment) until weaning 49 days later, at which point calves were offered solely CS until day 56. This study observed that the average daily gain (ADG) of crossbred calves receiving MR24 increased 23.4% and 23.6% during the preweaning and total experiment, respectively. Additionally, feeding MR24 to crossbred calves increased feed efficiency (gain/feed, kg/kg) by 9.80% during the entire 56-day period compared with MR20. Milk replacer treatment had no impact on fecal scores of beef × dairy crossbred calves during the preweaning period or entire experiment.

•24% CP and 24% fat milk replacer improved ADG in beef × dairy calves.•24% CP and 24% fat milk replacer increased gain per feed and energy and protein intake.•24% CP and 24% fat milk replacer increased starter intake during late preweaning.•Fecal scores and scouring incidence were not affected by milk replacer composition.

24% CP and 24% fat milk replacer improved ADG in beef × dairy calves.

24% CP and 24% fat milk replacer increased gain per feed and energy and protein intake.

24% CP and 24% fat milk replacer increased starter intake during late preweaning.

Fecal scores and scouring incidence were not affected by milk replacer composition.

It is becoming more prominent for dairy producers to breed their lower genetic merit cows and heifers to beef sires to increase the value of calves when they are sold to beef markets. However, data are currently lacking on optimal feeding strategies for rearing these crossbred calves until weaning. Therefore, the objective of the current study is to compare the effects of feeding 2 milk replacers (20% CP and 20% fat [MR20] vs. 24% CP and 24% fat [MR24]) on calf growth, feed efficiency, and scouring frequency. Forty individually housed 2- to 5-d-old Angus × Holstein crossbred calves with a BW ranging from 34.0 to 47.6 kg were randomly assigned to 1 of 2 milk replacer (MR) treatments. Calves were fed 2.84 L of their respective MR twice per day (5.68 L total) from d 1 to 42 of the experiment and 2.84 L once per day from d 43 to 49. Feeding crossbred calves MR24 increased ADG and gain per feed by 23.6% and 9.80%, respectively, compared with calves fed MR20 from d 1 to 56. Feeding crossbred calves MR24 tended to increase calf starter intake and total feed intake compared with calves receiving MR20. Results suggest feeding a MR of higher nutritive value is a simple and effective strategy to increase weight gain and feed efficiency of beef × dairy calves.