Sorghum forage is an important alternative to high-quality forage in regions where climatic and soil conditions are less desirable for corn production for silage and producing comparable nutritive value is challenging. The objective of this experiment was to assess the effects of season (spring vs. summer), sorghum variety type (forage sorghum vs. sorghum-sudangrass), and trait [brown midrib (BMR) vs. non-BMR] on dry matter (DM) yield, nutrient composition, and predicted intake and milk yield of whole-plant sorghum forage grown in Florida from 2008 to 2019. Whole-plant sorghum forage was harvested at a targeted 32% of DM, and each year, spring (April) and summer (July) trials were established. A total of 300 forage sorghum and 137 sorghum-sudangrass hybrids were tested for a total of 437 hybrids, of which 199 hybrids contained the BMR trait and 238 were non-BMR. An interaction between season and sorghum variety type was observed for DM yield. Dry matter yield was greater for the spring season than the summer season, with sorghum-sudangrass outperforming forage sorghum only during the spring season. In addition, BMR hybrids had a lower DM yield than non-BMR hybrids, regardless of season and variety type. An interaction between season and trait was observed for predicted neutral detergent fiber digestibility after 30 h of incubation in rumen fluid (NDFD_30h). Predicted NDFD_30h was greater for BMR sorghum in comparison to non-BMR sorghum, but BMR sorghum had slightly greater predicted NDFD_30h when grown in the spring than summer, whereas no seasonal differences were found for predicted NDFD_30h across non-BMR sorghum. An interaction between season, variety type, and trait was observed for predicted dry matter intake at 45 (DMI₄₅), 55 (DMI₅₅), and 65 (DMI₆₅) kg of milk/d. Predicted DMI₄₅ and DMI₅₅ were greater for spring BMR forage sorghum than for spring and summer non-BMR sorghum-sudangrass and were greater for spring BMR forage sorghum than for summer BMR sorghum-sudangrass. Predicted DMI₆₅ was greater for BMR forage sorghum in comparison to all non-BMR hybrids in the spring. Additionally, spring BMR forage sorghum was greater than summer sorghum-sudangrass regardless of trait. An interaction between season and sorghum variety type was observed for milk yield per megagram of forage. Milk yield per megagram of forage was greatest for spring forage sorghum. Sorghum variety type and trait selection are crucial to minimize differences in forage nutritive value of sorghum forage between seasons and improve the performance of high-producing dairy cows.

Our objective was to assess the effect of forage processor roll gap width and storage length on fermentation, nutrient composition, kernel processing score (KPS), and ruminal in situ starch disappearance (isSD) of whole-plant maize silage harvested at different maturities. Samples from a single maize silage hybrid at three harvest maturities (1/4, 1/2, and 3/4 kernel milk line (early, intermediate, and late, respectively)) processed with two roll gap widths (1 and 3 mm) were collected and stored in quadruplicate vacuum pouches for 0, 30, 120, or 240 d. Lactic acid concentrations were greater, and pH was reduced in early and intermediate maturity silage compared to late maturity silage. Ruminal isSD was greatest for early maturity silage, intermediate for the intermediate maturity silage, and lowest for the late maturity silage, but differences in isSD due to maturity were diminished after prolonged storage. Kernel processing score was greatest in late maturity silage processed through a 1 mm roll gap and lowest in late maturity silage processed through the 3 mm roll gap. For early and intermediate maturity silages, no differences in KPS were observed between the two roll gap widths. Minimal effects of maturity and roll gap width on fatty acids (FA) and amino acids (AA) were observed. Concentrations of total AA decreased as storage length progressed. Results support the premise that the silo is a dynamic system that undergoes numerous chemical changes throughout the storage period.

Dairy cows contribute to climate change primarily through enteric methane (CH₄) emissions. Several mitigating strategies have been evaluated, including the inhibitor 3-nitrooxypropanol (3-NOP). Our objectives were to (1) evaluate the effect of feeding 3-NOP in dairy diets on lactation performance and income over feed costs (IOFC) per cow and per farm, and (2) discuss the potential implications for dairy producers. Data from 15 articles (16 experiments) met the selection criteria, with a total of 412 lactating cows used. The analysis calculated the mean difference data from the 3-NOP treatment mean minus the control treatment mean from that of the NOP-supplemented group. A mixed effects model was fitted to the data. The model included 3-NOP supplementation as fixed effect, and study as a random effect. The 3-NOP dose (mg/kg DM) was included as an explanatory variable. The presence of bias was evaluated by Egger's test, but no publication biases were observed for any of the responses of interest. Income over feed costs per cow per day was calculated based on statistically significant changes in feed consumption, milk yield, and values of milk fat and protein produced less costs for diets feeding 3-NOP. The effects of changes in IOFC were evaluated for herds with different numbers of milking cows (100, 250, and 1,000 lactating cows). Dairy cows fed 3-NOP had 0.5 kg/d lower DMI and a reduction in milk yield of 0.7 kg/d compared with control cows. Milk fat and protein yields were unaffected for dairy cows supplemented with 3-NOP compared with control. Similarly, the ECM yield and feed efficiency were unaffected for dairy cows supplemented with 3-NOP compared with control. However, dose of 3-NOP was negatively associated with the 3-NOP effect size on these performance-related parameters. Feeding 3-NOP caused a reduction of 27.9% for CH₄ production at an average 3-NOP dose of 80.3 mg/kg DM. Given changes in DMI, milk yield, and milk fat and protein, supplementation of 3-NOP decreased mean IOFC by $0.35 cow^-1/d^-1 for a cow producing 39 kg/d. These effects on IOFC indicate that under present economic conditions, dairy farmers will need to be compensated by participation in carbon credits programs, provided other incentives for emissions reduction, or both. Reduction of methane emissions with 3-NOP supplementation requires compensation of -$128,320/yr for a dairy with 1,000 milking cows. In addition, the breakeven compensation for use of 3-NOP varied from -$0.42 cow^-1/d^-1 to -$0.21 cow^-1/d^-1 based on feed and milk component values from 2014 to 2023. Future research is warranted to evaluate long-term effects of feeding 3-NOP on the productivity of dairy cows.

The objective of this study was to evaluate the effects of supplementing an essential oil blend (0.16 g/kg DM of carvacrol, eugenol, thymol, and capsaicin) and monensin (17.6 mg/kg DM TMR) on lactation performance, feeding behavior, and rumen fermentation of high-producing dairy cows. Sixty-four multiparous Holstein cows (89 ± 21 DIM and 729 ± 68 kg of BW at covariate period initiation), including 16 cannulated cows, and 32 gate feeders were enrolled in a study with a completely randomized design and a 2 × 2 factorial arrangement. Cows and gate feeders were randomly assigned to treatments (4 cannulated cows and 12 cows not cannulated for a total of 16 cows, and 8 gate feeders per treatment). Cows were allowed 1 wk to acclimate to gate feeders followed by a 2 wk covariate period. During the acclimation and covariate periods, all cows were fed a diet containing EOB and MON. Following the covariate period, cows were enrolled in a 10 wk treatment period during which cows were randomly assigned to 1 of 4 treatments: 1) a combination of the essential oil blend and monensin (EOB-MON), 2) the essential oil blend alone (EOB), 3) monensin alone (MON), or 4) neither the essential oil blend nor monensin (CON). Data were analyzed using a mixed model with week as a repeated measure and fixed effects of essential oil blend, monensin, week, and all their interactions. Cow (treatment) was included as a random effect. The average covariate period value of each variable was used as a covariate. A 3-way interaction was observed for DMI, where DMI was lowest for CON and MON for wk 1, but then was lowest for EOB during wk 4, 9, and 10. Supplementing the essential oil blend also decreased body weight during wk 4 and 10 and tended to decrease body weight change but increased the maximum pH in the rumen. Monensin tended to improve milk production and lactose yield, but decreased milk fat concentration without affecting milk fat yield. Thus, feeding monensin appears to improve milk yield, while maintaining or increasing component yields. However, feeding dairy cows a combination of carvacrol, eugenol, thymol, and capsaicin decreased DMI for 3 out of 10 wks at the expense of body weight gain.

The objective of this experiment was to evaluate the effects of dietary starch concentration by replacing high-moisture corn with soy hulls and a direct-fed microbial (DFM) containing Bacillus subtilis 810 and Bacillus licheniformis 809 on the lactation performance, feeding behavior, total-tract nutrient digestibility, and enteric CH₄ emissions of dairy cows. Sixty-four multiparous Holstein cows (67 ± 24 DIM and 729 ± 60 kg of BW at the beginning of the covariate period) were randomly assigned to 1 of 4 treatments with a 2 × 2 factorial arrangement for a 12-wk treatment period, after a 1-wk acclimation period and 2-wk covariate period. Treatments consisted of diets with 21% starch and no DFM (RS-CON), 21% starch and DFM (RS-DFM), 27% starch and no DFM (NS-CON), and 27% starch and DFM (NS-DFM). Data were analyzed as a completely randomized design using a mixed model including a covariate and dietary starch, DFM supplementation, week, and their 2- and 3-way interactions as fixed effects. Cow within treatment was a random effect. Diets with 21% starch increased DMI and milk fat concentration but decreased feed efficiency. Cows fed DFM tended to have greater lactose concentration than those not fed DFM (CON). Milk yield and milk protein concentration did not differ. The eating rate was lower and meal length was greater for DFM than CON. Cows fed 27% starch had a lower eating time, meal length, intervals between meals, and smaller meal sizes than 21% starch diets. Meal frequency increased with greater starch. Diets with 27% starch reduced CH₄ emissions and intensity and tended to reduce CH₄ yield. Digestibility of DM, OM, CP, ether extract, and NDF was greater for DFM than CON diets. The replacement of high-moisture corn with soy hulls increased milk fat concentration but not milk yield. Diets with 27% starch decreased CH₄ production and improved feed efficiency compared with 21% starch diets. Additionally, feeding cows DFM improved total-tract nutrient digestibility compared with CON.

Two experiments were conducted to evaluate the effects of a genetically modified corn hybrid with α-amylase expressed in the kernel (AMY) on fermentation profile, aerobic stability, nutrient composition, and starch disappearance of whole-plant corn silage (WPCS) and earlage. Both hybrids, AMY and an isogenic corn hybrid (ISO), were grown in 10 replicated plots (5 for WPCS and 5 for earlage). Samples of each plot were collected at harvest, homogenized, and divided into 5 subsamples which were randomly assigned to 5 storage lengths (0, 30, 60, 90, and 120 d). Both datasets (WPCS and earlage), were analyzed separately as a completely randomized block design in a factorial arrangement of treatments, with a model including the fixed effects of hybrid, storage length, and their interaction, and the random effect of block. Minor differences on fermentation profile were observed between AMY and ISO for WPCS and earlage. An interaction between hybrid and storage length was observed for DM losses in WPCS, where losses were similar at 30, 60 and 90 d, but lower for AMY compared with ISO at 120 d. No effect of hybrid was observed on yeast and mold counts for WPCS or earlage. The aerobic stability of WPCS was greater for AMY than ISO. For earlage, AMY had greater DM losses and aerobic stability than ISO. An interaction between hybrid and storage length was observed for ammonia-N in both WPCS and earlage, where ammonia-N was similar at 0 d but greater for AMY than ISO throughout later storage lengths. A similar interaction was observed for water-soluble carbohydrates (WSC) concentrations in WPCS, where ISO had greater WSC than AMY at 0 d but was similar throughout later storage lengths. However, AMY earlage had a greater WSC concentration throughout storage length, but a lesser magnitude after ensiling. Starch concentration was greater for AMY than ISO in WPCS and earlage. Greater starch disappearances at 0 h and 6 h were observed for ISO in WPCS and earlage. Minor effects on fermentation profile, microbial counts, aerobic stability and nutrient composition suggests that AMY can be ensiled for prolonged periods with no concerns for undesirable fermentation or nutrient losses. However, in situ starch disappearance was lower for AMY compared with ISO.