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The objective of this study was to evaluate the effects of dietary fiber source and direct-fed microbial supplementation on lactation performance and feeding behavior of high-producing dairy cows. Sixty-four multiparous Holstein cows (3.5 ± 1.6 lactations; 76 ± 22 DIM and 735 ± 67 kg of BW at covariate period initiation) 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 (16 cows and 8 gate feeds per treatment). Cows were allowed 1 week to acclimate to feeding gates followed by a 2-week covariate period. During the acclimation and covariate periods, all cows were fed the same diet to meet or exceed the nutrient requirements. Following the covariate period, cows were enrolled in a 8-week treatment period during which cows were randomly assigned to 1 of 4 treatments consisting of forage inclusion in the diet, either 45.8% (LF) or 56.7% (HF) of DM, and the supplementation of 75 mL/hd/d of a direct-fed microbial (DFM) containing herbal extracts (mallow, mint, and sage), L. plantarum, L. buchneri, Saccharomyces cerevisiae, and sugar cane molasses (Valibiom Mix, Valibiotics, Traiskirchen, Austria) or without supplementation (CON). The average covariate period value of each variable was used as a covariate. Three-way interactions were observed for DMI and feed efficiency. Dry matter intake was 2 to 3 kg greater for LF-DFM than HF-CON and HF-DFM during wk 2, 3, 5, and 8 of the treatment period. Milk production was 2.1 kg/d greater for LF than HF diets. Both milk fat and MUN concentrations were greater for HF than LF diets. Conversely, milk protein concentration was lower for HF than LF diets. The respiration rate measured in the morning was lower with DFM supplementation than CON. Rectal temperature measured in the morning and averaged for the day were greater for LF than HF diets. Under the conditions of the present study, feeding high-forage diets may be an alternative for producers to reduce feeding costs depending on the price of purchased feeds. However, non-forage fiber sources (i.e., soy hulls) must be considered when producers are challenged by either forage shortages or forage with a lower nutritive value. Additionally, DFM supplementation reduced respiration rate in the morning and affected meal behavior of lactating cows., (The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

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., (The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

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 (DMI 45 ), 55 (DMI 55 ), and 65 (DMI 65 ) kg of milk/d. Predicted DMI 45 and DMI 55 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 DMI 65 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., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)