Strategies to improve the nutritive value of whole-plant corn silage in diets for finishing beef cattle

Whole-plant corn silage (WPCS) is a major source of forage for feedlot beef cattle in Brazil. During the ensilage process, the type of harvesting equipment and the silo sealing, cause changes in the silage and affect its nutritional value. Nonetheless, two trials were conducted to evaluate the effect of processing and inclusion level of WPCS and sealing strategies on the performance of finishing beef cattle. In the first trial, the objective was to evaluate the effect of WPCS processing with self-propelled or pull-type forage harvester on the performance of beef cattle in diets with high and low forage inclusion. The WPCS was harvested with approximately 30% dry matter (DM) with pull-type forage harvester (PTFH, without kernel processor, New Pecus PRF 2-4555) or self-propelled forage harvester (SPFH, with kernel processor, New Holland FR 500), adjusted for theoretical length of cut of 10 mm. Storage time was 219 days. Sixty Nellore bulls (405 kg ± 29,1 kg, 24 months old) were distrusted in blocks and allocated in 20 pens (3 animals per pen) for 102 days (12 days of adaptation + 90 days of diets comparison). The experimental diets were: 1) 15% WPCS harvested with PTFH; 2) 33% WPCS harvested with PTFH; 3) 15% WPCS harvested with SPFH; 4) 33% WPCS harvested with SPFH. Silage samples were collected from the silo panel to evaluate composition, fermentation products, temperature, density, pH and losses. Dry matter intake (DMI) was measured daily, whereas shrunk body weight (SBW) and other animal variables were measured at the beginning, middle and end of the diet comparison period. Silage data were presented as mean and standard deviation, and animal performance was analyzed as a randomized complete block design. The inclusion of 33% WPCS increased DMI by 10% (9.88 vs. 10.91 kg DM/d) and average daily gain by 14% (1.386 vs. 1.585 kg/d). different sealing strategies. Dry matter intake (DMI) was measured daily, while SBW and other animal variables were measured at the beginning, middle and end of the feeding trial period. Silage and animal performance data were analyzed as a complete randomized block design. The silages stored under OB film protected with PE120 showed higher mold counts. Losses during silage feed-out were higher for films protected with PE120. During storage, the sealing strategy with anti-UV cover showed 9.60°C higher at 11:00 am and 4.22°C higher at 4:00 pm, compared to cover by PE120 film. The highest silage temperatures were verified in the upper layer, and the highest densities, in the bottom layer of the silo. Animals that received a diet containing silage from the PE120+OB treatment showed greater daily variation in DMI. The DMI, average daily gain and other carcass characteristics were similar between treatments. The results suggest that the protection of both films with an anti-UV or PE120 cover, equally affected silage quality and animal performance. Abstract Whole-plant corn silage (WPCS) is the main source of forage for beef cattle in confinement in Brazil. Forage harvester cause modifications to the WPCS that affect animal performance. The objective of this study was to evaluate the extent of the effect of processing WPCS with either a self-propelled or a pull-type forage harvester on the performance of beef cattle in diets with high and low forage inclusion. The WPCS was harvested to reach approximately 30% dry matter (DM) with pull-type forage harvester (PTFH, without kernel processor, New Pecus PRF 2-4555) or self-propelled forage harvester (SPFH, with kernel processor, New Holland FR 500), both adjusted for theoretical length of cut of 10 mm. After 219 days of storage, the silos were opened for feeding to 60 Nellore bulls (405 kg ± 29.1 kg, 24 months of age). The cattle were blocked by initial shrunk body weight (SBW), distributed in 20 pens (3 animals per pen) for 102 days (12 days of adaptation + 90 days of diets comparison). The experimental diets were set in a factorial design: 1) 15% WPCS harvested with PTFH; 2) 33% WPCS harvested with PTFH; 3) 15% WPCS harvested with SPFH; 4) 33% WPCS harvested with SPFH. Silage samples were collected from the exposed feed face to measure chemical composition, fermentation products, temperature, density, pH and losses. Dry matter intake (DMI) was measured daily, whereas SBW and other animal variables were measured at the beginning, middle and end of the diet comparison period. Silage data were presented as mean and standard deviation, and animal performance was analyzed as a randomized complete block design. The 33% WPCS diet increased DMI by 10% (9.88 vs. 10.91 kg DM/d) and average daily gain by 14% (1.386 vs. 1.585 kg/d). Gain and carcass weight also improved with 33% WPCS in the diet. In addition, the increase in rumination, chewing, number of meals, and intake rate were results of a greater inclusion of WPCS in the diet. The performance and carcass characteristics of the cattle were similar for both harvesters. The interaction between harvesters and level of inclusion showed that cattle fed the 15% WPCS processed with SPFH preferred particles longer than 19 mm and medium particles between 8-19 mm. There was selection against fine particles. The estimated net energy of maintenance and the total digestible nutrients of the silage were higher when the diet changed from 15 to 33% WPCS. Pressure and oxygen saturation in blood samples increased, while fecal pH decreased, for cattle of treatment with 15% WPCS. In conclusion, the greater inclusion of WPCS in the diet improved the performance of finishing beef cattle. The forage harvester used WPCS processing did not influence the performance of beef cattle in feedlot. Abstract The study compared the performance of beef cattle fed diets based on whole-plant corn silage (WPCS) sealed with thin films, with or without oxygen barrier (OB), protected with an anti-ultraviolet (anti-UV) cover or double-sided polyethylene (PE) film. The WPCS was harvested at 32% dry matter (DM) and packed in four duplicate silos (total of eight silos) simultaneously. The silos were divided transversally, and four treatments were applied to each one, as follows: 45 µm OB film protected with anti-UV cover (anti-UV +OB); 45 μm OB film protected with 120 μm double-sided PE film (PE120+OB); 50 μm PE film protected with anti-UV cover (anti-UV+PE50); 50 μm PE film protected with 120 μm double-sided PE film (PE120+PE50). The storage time of the first four silos was 300 days and the other four, 347 days. Silage samples were taken from the external surface of the silo to determine silage composition, fermentation products, microbial count, temperature, pH and dry matter loss. Sixty-four Nellore bulls (456 ± 42.8 kg) were blocked by initial shrunk body weight (SBW) and allotted in individual pens for 103 days (13 days of adaptation to facilities + 90 days of feeding trial). The experimental diets contained (on a DM basis) 70% concentrate and 30% corn silage from the different sealing strategies. Dry matter intake (DMI) was measured daily, while SBW and other animal variables were measured at the beginning, middle and end of the feeding trial period. Silage and animal performance data were analyzed as a complete randomized block design. The silages stored under OB film showed higher mold counts. Losses during silage feed-out were higher for films protected with PE120. The anti-UV cover showed temperatures 9.60°C higher at 11:00 am and 4.22°C higher at 4:00 pm, during storage, compared to PE120. The highest silage temperatures were verified in the upper layer, and the highest densities, in the bottom layer of the silo. Animals fed a diet with silage from the PE120+OB treatment showed greater daily variation in DMI. The DMI, average daily gain and other carcass characteristics were similar between treatments. In conclusion, the protection of both thin films with an anti-UV or PE120 coating attenuated the influence of silo covering film on animal performance.