Effects of corn silage and grain expressing α-amylase on ruminal nutrient digestibility, microbial protein synthesis, and enteric methane emissions in lactating cows

Lactational performance, ruminal fermentation, and enteric gas emission of dairy cows fed an amylase-enabled corn silage in diets with different starch concentrations

This study investigated the effects of feeding an amylase-enabled corn silage (ACS) on the performance and enteric gas emissions in lactating dairy cows. Following a 2-wk covariate period, 48 mid-lactation Holstein cows were assigned to 1 of 3 treatments in a 10-wk randomized complete block design experiment. Treatments were diets containing the same proportion of corn silage (40% of dietary DM) as follows: (1) a conventional hybrid corn silage control (CON), (2) ACS replacing the control silage (ADR), and (3) the ADR diet replacing soybean hulls with ground corn grain to achieve the same dietary starch concentration as CON (ASR). Control corn silage and ACS were harvested on the same day and contained 40.3% and 37.1% DM and (% of DM): 37.2% and 41.0% NDF and 37.1% and 30.0% starch, respectively. Enteric gas emissions were measured using the GreenFeed system. Two cows were culled due to health-related issues during the covariate period. Ruminal fluid was collected from 24 cows (8 per treatment) using the orogastric ruminal sampling technique. When compared with CON, cows fed ADR had increased DMI during experimental wk 3, 4, and 9, but treatment did not affect milk or ECM milk yields (39.0 kg/d on average; SEM = 0.89). Compared with CON, feed efficiency (per unit of milk, but not ECM) tended to be lower for ADR, whereas milk true protein concentration (a tendency) and yield were lower for ASR. Milk urea N was decreased by both ADR and ASR diets relative to CON. Compared with CON, daily CH4 emission and emission intensity were increased by ADR but not ASR. Total protozoal count tended to be increased by both diets formulated with ACS when compared with control corn silage. Total-tract digestibility of dietary NDF was greater for ASR, and that of ADF was greater for both ADR and ASR versus CON. The molar proportion of acetate (a tendency) and acetate-to-propionate ratio were increased by ADR, but not ASR, when compared with CON. Replacement of CON with ACS (having lower starch concentration) in the diet of dairy cows increased DMI during the initial weeks of the experiment, maintained ECM, tended to decrease feed efficiency, and increased enteric CH4 emissions, likely due to increased intake of digestible fiber, compared with CON.

Effects of a genetically modified corn hybrid with α-amylase and storage length on fermentation profile and starch disappearance of whole-plant corn silage and earlage

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.

Effects of feeding α-amylase-expressed corn silage and grain on performance, enteric methane production, and carcass characteristics in beef steers

An experiment was conducted to evaluate the effects of feeding Enogen feed corn (EFC) silage or EFC grain with different grain processing (dry-rolled corn vs. whole-shelled corn) in feedlot cattle diets. Total 68 Angus cross-bred steers were blocked by body weight and the treatments (diets) were randomly assigned to steers in each block: a basal diet with isoline corn silage and isoline dry-rolled corn grain (IIR); the basal diet with EFC silage and isoline dry-rolled corn grain (EIR); the basal diet with EFC silage and EFC dry-rolled grain (EER); and the basal diet with EFC silage and EFC whole-shelled grain (EEW). Isoline refers to the isogenic counterpart of Enogen corn silage or grain. Steers received the assigned treatment over 32 wk of the entire experiment (backgrounding and finishing) until harvested. Part of the steers (eight blocks) in each treatment were used to measure CH4 production (g/d) using the GreenFeed and CH4 production per unit of DMI. All data were analyzed using a mixed procedure of SAS in a randomized complete block design, considering diet as a fixed effect and block as a random effect. Steers fed the EIR diet increased (P = 0.03) DMI compared to IIR during the backgrounding phase. However, feeding EFC silage or grain did not affect body weight, average daily gain, and feed efficiency during backgrounding and finishing phases. Feeding EEW decreased (P ≤ 0.05) body weight, average daily gain, feed efficiency, and tended to decrease (P = 0.06) hot carcass weight compared to EER during the finishing phase. Methane production per unit of DMI decreased (P = 0.02) for steers fed EIR compared with steers fed IIR only during the backgrounding phase. Feeding EFC grain had no effect on CH4 production (g/d) in both phases. In conclusion, feeding EFC silage or grain did not improve the performance of beef steers during the backgrounding and finishing phases in the current experiment condition. Methane production per unit of DMI was reduced for steers fed EFC silage compared with isoline corn silage only during the backgrounding phase.