Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/18/2010
Publication Date: 10/21/2010
Citation: Kruse, K.A., Combs, D.K., Esser, N.M., Coblentz, W.K., Hoffman, P.C. 2010. Evaluation of Potential Carryover Effects Associated with Limit Feeding Gravid Holstein Heifers. Journal of Dairy Science. 93:5374-5384. Interpretive Summary: Replacement dairy heifers often gain too much weight and become overconditioned when they are offered diets consisting of corn silage or other high-energy forages. Many heifer rearing operations prefer to feed corn silage diets because of its attractive harvest and feeding efficiencies. One way to limit energy intake and prevent overconditioning is to limit-feed these diets. Limit-fed diets are offered for restricted intake, but contain higher nutrient densities. Pregnant Holstein dairy heifers were offered control (unlimited access) or limit-fed diets for 180 days and then evaluated for growth, feed efficiency, rumen digesta volume, nutrient excretion, and lactation performance. Limit-fed heifers consumed less dry mater, had greater gain, and improved feed efficiency when compared to control-fed heifers. Rumen fermentation characteristics and digesta volume were unaffected by limit feeding during the 180-day growth trial. After calving, previous limit-feeding management of heifers did not affect body weight, dry matter intake, rumen digesta volume, and milk or milk-component yields during first lactation. Limit-feeding of replacement dairy heifers offers considerable potential for dairy producers to retain the option of feeding corn silage without overconditioning, or affecting the subsequent productive life of these dairy animals.
Technical Abstract: Ninety-six Holstein heifers (400 ± 6 kg, 15.2 ± .1 mo ) that included 9 fit with ruminal cannula were offered 1 of 3 diets for 180 ± 8 d in a randomized replicated pen design. Dietary treatments included a control diet (C100), and two independent limit-fed (LF) diets. The LF diets included one offered at 85% of C100 intake (L85) without an ionophore, and a second containing an ionophore (325 mg/hd/d of lasalocid) that was offered at 80% of C100 intake (L80+I). Heifers were evaluated for growth, rumen digesta volume, nutrient excretion and subsequent lactation performance. Limit-fed heifers consumed less dry matter, neutral detergent fiber, and had greater respective average daily gains (0.96 or 0.89 vs. 0.81 kg/d), and lower feed:gain ratios (9.1 or 9.3 vs. 13.0 kg/kg) compared to heifers offered the C100 diet. No differences in rumen pH, NH3-N, or volatile fatty acid concentrations were observed between C100 and LF heifers. Rumen digesta volume, density, and weight were unaffected by LF, and feeding L85 or L80+I did not result in carryover effects for rumen digesta volume when these heifers were offered a common high fiber diet immediately after the 180-d growth trial. At parturition, no differences were observed for dystocia index, calf body weight or 7-d postpartum body weight between cows offered LF or C100 diets as heifers. Lactation body weight, dry matter intake (DMI), and feed efficiency of cows did not differ between treatments at 45 or 90 days in milk. Milk yield and milk components also were not different between cows that were offered C100 or LF diets as gravid heifers. At 45 days in milk, rumen digesta volume was greater (99.1 vs. 66.1 L) for cows offered L85 compared to cows offered L80+I as gravid heifers, but this effect was not observed at 90 d in milk. Limit feeding of gravid Holstein heifers for 180 d did not result in any carryover effects during their first lactation for rumen digesta volume, DMI, or milk yield.