As the hemp industry continues to develop in the United States, there is an increasing interest in feeding byproducts of industrial hemp production to livestock. A completely randomized design experiment using crossbred finishing heifers (initial body weight [BW] ± SE = 494 ± 10 kg) was conducted to determine the effects of feeding hempseed cake in a corn-based finishing diet (10% forage) formulated to meet or exceed ruminally degradable and metabolizable protein requirements on growth performance, carcass characteristics, feeding behavior, and plasma parameters. Dietary treatments were the inclusion of 20% (dry matter [DM] basis) of dried corn distillers grains plus solubles (DDGS, n = 16) or hempseed cake (HEMP, n = 15). Cattle were housed in two pens, had ad libitum access to feed and water, and individual intakes and feeding behavior were monitored using the Insentec feeding system. Cattle were fed treatment diets for 111 d, and every 14 d BW were measured and blood samples were collected. Blood plasma was analyzed for glucose, urea nitrogen, and individual amino acids, and results were analyzed using repeated-measures analysis in SAS. Final BW, average daily gain, gain:feed, and hot carcass weight decreased (P ≤ 0.05) by 2.3%, 7.7%, 7.7%, and 2.6%, respectively, in heifers fed the HEMP diet than in heifers fed the DDGS diet. Net energy for maintenance and gain (Mcal/kg of feed, DM basis), estimated based on heifer intake and performance, were greater (P = 0.02) for the DDGS diet than for the HEMP diet. All other performance and carcass characteristics were not different (P ≥ 0.20) between treatments. Heifers fed the HEMP diet had greater (P < 0.05) plasma urea nitrogen concentration in samples from each collection day compared with heifers fed the DDGS diet, although there was a treatment-by-day interaction (P < 0.01) because of variability in the magnitude of treatment differences over time. Plasma glucose concentration was not influenced (P = 0.17) by dietary treatment. Plasma concentrations of total amino acids, nonessential amino acids, and essential amino acids were not different between treatments (P ≥ 0.09), although there were several interactions between treatment and day (P ≤ 0.04) for individual amino acids. These data suggest that hempseed cake has a lower net energy for maintenance and gain relative to DDGS when adequate metabolizable protein is supplied, while still providing adequate nutrition to support the acceptable performance of finishing cattle.
Keywords: animal performance; finishing cattle; hempseed cake; nutrition; plasma metabolites.
This experiment evaluated the effects of dietary inclusion of hempseed cake in comparison with dried corn distillers grains plus solubles (DDGS) on growth performance, feeding behavior, carcass characteristics, and blood parameters in finishing heifers. Angus-crossbred heifers were assigned randomly to one of two treatments (20% hempseed cake [HEMP] or 20% DDGS; dry matter basis) and were fed for 111 d until slaughter. Heifers receiving the DDGS treatment had greater final body weights, average daily gain, gain efficiency, dietary concentration of net energy for maintenance and gain, and carcass weight than heifers fed the HEMP treatment. All other carcass characteristics, as well as feeding behavior, were not influenced by treatment. Plasma urea nitrogen was greater in heifers fed the HEMP diet compared with the DDGS diet, while glucose was not influenced by treatment. Several plasma amino acid concentrations were influenced by treatment. Although the inclusion of hempseed cake decreased growth performance, it could be a viable alternative feed source for cattle.
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