Hempseed meal (HSM) is left after oil extraction of hemp and may act as a protein source in livestock. The first phase of this research evaluated variation in nutritive value and in vitro dry matter digestibility (IVDMD) of HSM from various sources in North America; the second phase utilized IVDMD to evaluate the efficacy of hempseed meal as an ingredient in ruminant feed. In phase one, the source had no contribution to variance for neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), or crude protein (CP) (p ≥ 0.20). However, batch within source contributed to variation for NDF (50%), ADF (37%), ADL (13%), and CP (31%; p ≤ 0.01). Irrespective of differences in nutritive value, there was no contribution to variation (p = 0.23) of any measured response on in vitro true digestibility (53.0%). In phase two, two experiments evaluated HSM IVDMD as (1) a concentrate replacement or (2) a protein replacement in rations at varying rates. In the first experiment, IVDMD decreased (p < 0.05) with increasing levels of HSM. In the second experiment, IVDMD decreased (p < 0.01) as HSM inclusion increased. Although IVDMD decreased as HSM inclusion increased, values still met the digestibility threshold for ruminant rations, indicating that HSM has potential as an alternative protein ingredient.

Ruminant in vitro methodologies use washing with neutral detergent solution (NDS) after incubation to mimic ruminant digestion, which is physiologically different compared to that of horses. Our objectives were to determine if washing feed samples with NDS before in vitro fermentation (PRE) would suppress fiber digestion versus a post-incubation wash (POST), and to compare in vitro digestibility of forage-based feed mixtures with added soluble carbohydrates (CARB), soluble protein (PROT), or soluble carbohydrates and soluble protein (C + P) to only-forage samples (CONT). Dried, ground feed mixtures sealed in ANKOM filter bags were placed in Daisy^II incubators for 48 h in a split–split-plot batch culture design. Digestibility was determined as in vitro neutral detergent fiber digestibility (IVNDFD), in vitro acid detergent fiber digestibility (IVADFD), in vitro hemicellulose digestibility (IVHD), and in vitro true digestibility (IVTD). The PRE treatment decreased IVHD for CARB versus POST (p = 0.007). Pooling all mixtures, PRE decreased IVTD (p = 0.001), IVADFD (p = 0.036), and IVHD (p = 0.001) and tended to decrease IVNDFD (p = 0.072). The CARB mixture increased IVTD versus all other mixtures (p < 0.001). Pre-washing with NDS suppressed in vitro fermentation by removing soluble carbohydrates. Without removal of soluble carbohydrates to mimic in vivo digestion, fiber digestibility is likely overestimated.

Saccharomyces cerevisiae yeast products are used to stabilize dairy cattle rumen environments. In this study, multiparous lactating Holstein–Jersey cross cows in late lactation (n = 12; ±150 DIM) were used in a replicated 4 × 4 Latin square design over four 21 d periods to evaluate yeast supplementation on dry matter intake (DMI), milk production, milk components, rumen pH, and redox potential (E_h). A subset of four ruminally cannulated cows were selected for rumen measurements. Treatments included no additive (CON), 14 g yeast culture additive (YCA), 5 g active dry yeast (ADY), and 5 g ADY + 5 g yeast extract additive (YEA) top-dressed once daily. Data were analyzed using GLIMMIX in SAS 9.4, with significance at p ≤ 0.05 and tendencies at p ≤ 0.15. Dry matter intake did not differ among treatments (p > 0.15) but decreased over time (p < 0.05). Milk production, efficiency, lactose, and total solids were not affected (p > 0.15). YCA tended to increase milk fat and fatty acid fractions compared with CON (p < 0.15). Protein in milk was greater in CON (p < 0.05; p < 0.05) than YCA and YEA. Active dry yeast treatments increased the frequency of a buffered rumen (p < 0.05) and promoted a more reducing ruminal environment, characterized by lower redox potential and conditions favorable for anaerobic fermentation (p < 0.05). Overall, supplementing active dry yeasts to dairy cows in late lactation did not affect DMI, production efficiency, or milk quality, but may maintain rumen pH stability.

Mesquite (Prosopis L.) is considered an invasive browse species in most of the American Southwest. Mechanical intervention removes yields an excess of organic debris. Anecdotal evidence in the past has supported using such browse as feed for livestock. Thus, our objectives were to (1) determine the nutritive value and fermentation characteristics of silage produced with mesquite biomass, and (2) evaluate solvent treatment of mesquite biomass prior to ensiling. In Experiment 1, we evaluated mesquite inclusion rate (0, 250, 500, 750, or 1000 g kg⁻¹ DM), length of fermentation (28, 56, or 84 d), and silage inoculant. In Experiment 2, we evaluated the effects of mesquite pre-treatment with acid (H₂SO₄) or alkali (NaOH) solutions. Concentrations of NDF, ADF, and ADL, as well as IVTD, decreased (p < 0.05) with increasing mesquite inclusion. However, 250 g mesquite kg⁻¹ DM did not differ from grass silage. There was no effect (p > 0.05) of inoculation, though increasing length of incubation did increase (p < 0.05) VFA production and decrease (p < 0.05) silage pH. Solvent treatment did not improve ensiling properties. Results are interpreted to mean that mesquite biomass may be effectively incorporated into silage at levels up to 250 g kg⁻¹.

Mesquite (Prosopis glandulosa Torr.) is considered an invasive browse species in most of the American Southwest. Over the past several decades, mesquite has spread rapidly in Texas, leading to destruction of native grasslands. In addition to trying to manage its encroachment on grazinglands, producers have been known to use mesquite wood in times of drought as a feed source for livestock, specifically in cow/calf production. This also represents a potential sustainable solution to dealing with debris from brush control measures. Thus, our objective was to evaluate the inclusion of chipped mesquite wood as a partial grass replacement in silage production. This experiment used a factorial treatment structure of silage inoculant (yes, no), grass replacement (0, 25, 50, 75, 100%), and length of incubation (28, 56, 82 d). Bermudagrass [Cynodon dactylon (L.) Pers. cv. Coastal] was used as the grass base in the silage mixtures. Samples were incubated in a convection incubator at 29.4°C for their respective incubation lengths. Following incubation, each sample was assayed for NDF, ADF, ADL, CP, and IVTD, as well as a silage acid profile. There was no effect of inoculation, grass replacement, or incubation time (P ≥ 0.13) on CP (μ = 10%), nor was there an effect of inoculation or grass replacement (P ≥ 0.67) on NDF (μ = 70%). Both ADF and ADL increased (P < 0.05) with increasing inclusion of mesquite wood. In vitro true digestibility decreased (P < 0.05) with increasing inclusion of mesquite wood (50% from grass silage; 40% from mesquite silage). Results are interpreted to mean that mesquite wood may be used as a grass replacement in silage production at low inclusion levels.