Effects of Grass Hay vs. Silage-Based TMR on Performance of Dairy Calves around weaning

Historically milk fed dairy calves have not been given access to forage during the milk feeding period. However, the move towards feeding higher milk volumes has resulted in renewed interest in providing milk fed calves access to forage. The aim of this study was to compare feed intake and weight gain of dairy calves (n=108) offered two different forages and weaned using three gradual weaning methods. Weaning treatments were assigned to calves within each pen, and each pen was alternately assigned to Hay (mix of tall fescue, orchard grass) or a total mixed ration (lactating cow TMR: 46% concentrate, 32% corn silage, 14% grass silage, 6% alfalfa hay, 2% straw). All calves were offered 12 L/d of milk until d 30; milk was then gradually reduced by 25% of the individual’s average milk intake over 3 d. Milk was further reduced when calves either reached d 62 of age (milk reduced linearly until weaned at d 70), when each calf reached 3 specific forage and starter DMI targets (25% of milk removed at 200 g DM/d, 600 g DM/d, and weaned at 1150 g DM/d), or when each calf reached 200 g DM/d (milk reduced linearly until weaned at d 70). During weaning (d 31-69), Hay and TMR calves ate similar amounts of forage (0.09 vs 0.08 ± 0.01 kg DM/d, respectively) but Hay calves ate more starter (0.85 vs 0.65 ± 0.09 kg DM/d, respectively). Postweaning (d 70-84), Hay calves continued to consume more starter (2.81 vs 2.39 ± 0.1 kg DM/d, respectively) while TMR calves consumed more forage (0.3 vs 0.1 ± 0.02 kg DM/d, respectively). Over the 84 d calf rearing period, Hay calves consumed more DM than TMR calves (126.1 vs. 112.6 ± 3.5 kg DM, respectively), which likely explains the higher final BW of Hay calves (118.5 vs 112.7 ± 1.7 kg, respectively). There was no interaction between forage treatment and weaning method for feed intakes or final BW. We conclude that feeding grass hay over a silage-based TMR can promote starter intake and BW in calves fed a high milk allowance and weaned gradually. We also provide evidence that, despite historical beliefs, high milk fed calves can be offered forage during the milk-feeding period and still maintain high levels of performance.

Key words: forage, gradual weaning, weight gain.

Presented at the 2021 Animal Nutrition Conference of Canada. For information on the next edition, click here.