Effects of feeding varying levels of hempseed meal on dry matter intake, rumen fermentation, in vitro digestibility, blood metabolites, and growth performance of growing meat goats

Abstract

Objective: The objective of this study was to evaluate the effect hempseed meal (HSM; a by-product of hemp oil production) supplementation has on DMI, rumen fermentation, in vitro true digestibility, blood metabolites, and growth performance of growing meat goats over a 60-d feeding trial. Materials and Methods: Forty castrated Boer cross goats 4 to 5 mo of age with an average BW of 25.63 ± 0.33 kg were randomly assigned to 1 of 4 treatments (n = 10/treatment): control (0), 11%, 22%, and 33% HSM of the total diet on a DM basis. The forage to concentrate ratio was maintained at 50.2:49.8 on a DM basis, and timothy hay was used as a forage source. Diets were pelleted as TMR. Data were collected for DMI, rumen fermentation, blood metabolites, and growth performance for the 60-d feeding trial. Data were analyzed utilizing the GLM procedures of SAS (SAS Institute Inc.). Orthogonal contrasts for increasing HSM inclusion rates were used to determine linear and quadratic effects within the data. Results and Discussion: The DMI was similar among treatments (P > 0.05). Total live weight gain (kg) decreased linearly (P < 0.05) with increasing inclusion rate of HSM (10.75, 9.53, 8.48, and 7.80 kg for 0, 11, 22, and 33%, respectively). The ADG values followed the same trend (P < 0.05; 0.179, 0.159, 0.141, and 0.130 kg for 0, 11, 22, and 33%, respectively). Similarly, G:F decreased linearly (P < 0.05) with increasing HSM inclusion rates (0.116, 0.101, 0.090, and 0.085). Acetic, propionic, butyric, valeric, iso-valeric, iso-butyric acid, and total VFA concentrations decreased linearly (P < 0.05) with the increasing inclusion rate of HSM. Serum albumin and total protein showed quadratic responses (P < 0.05) with increasing levels of HSM, whereas BUN and creatine kinase levels increased linearly (P < 0.05). Implications and Applications: These findings provide new insights into the feeding value of HSM for meat goats; however, further research needs to be conducted to determine the optimal level of HSM supplementation.