Roughage level and supplemental fat for newly received finishing calves: effects on growth performance, health, and physiological responses. (5th January 2023)

• Record Type: Journal Article
• Authors: Gouvêa, Vinícius N; Oliveira, Mario O; Giacomelli, Hiam Jardel M; Colombo, Eduardo A; Batistel, Fernanda; Santos, Flávio A P; Duff, Glenn C; Marques, Rodrigo S; Cooke, Reinaldo F
• Is Part Of: Journal of animal science. Volume 101(2023)
• Publication Date: 2023-01-05
• Subjects: beef cattle -- fatty acids -- feedlot receiving -- fiber -- morbidity; Livestock -- Periodicals; Livestock; Electronic journals; Periodicals; 636.005
• DOI: 10.1093/jas/skac322
• Languages: English
• ISSNs: 0021-8812

Abstract

Abstract: This experiment evaluated the effects of roughage levels and supplemental fat on intake, growth performance, health, and physiological responses of newly received finishing cattle during 58-d receiving period. A total of 72 crossbred steers (initial body weight [BW] = 200 ± 13 kg) were used in a randomized complete block design with a 2 × 2 factorial arrangement of treatments, consisting of two roughage levels (wheat hay at 30% [R30] or 60% [R60]; dry matter [DM] basis) and two levels of supplemental fat (yellow grease at 0% [−FAT; no additional fat] or 3.5% [+FAT]; DM basis). Upon arrival, calves were individually weighed, blocked by off-truck shrunk BW, and assigned to 24 soil-surfaced pens (three calves per pen). Shrunk BW was also collected on day 58 for the calculation of average daily gain (ADG). Throughout the study, calves were assessed for bovine respiratory disease (BRD). Effects of roughage level × supplemental fat interaction were only observed for diet particle size distribution and estimated physically effective neutral detergent fiber ( pe NDF) of diets ( P ≤ 0.10). Adding fat to R60 diets tended to increase the percentage of particles retained in the 8-mm screen ( P = 0.06) and the estimated pe NDF ( P = 0.10), but did not affect R30 diets. Dietary roughage level did not affect DM intake (DMI; P = 0.85). Calves-fed R30 tended to have greater ADG and final BW than calves-fed R60 ( P ≤ 0.08). Gain efficiency (gain:feed ratio; G:F) was greater for calves-fed R30 than calves-fed R60 ( P = 0.01). Dietary roughage level did not affect morbidity and mortality ( P ≥ 0.11). Supplemental fat did not affect DMI ( P = 0.6) but tended ( P = 0.09) to increase ADG compared to –FAT diets. The G:F was greater for calves-fed +FAT than –FAT ( P = 0.03). The +FAT diet tended ( P = 0.10) to increase the number of retreatments against BRD compared to −FAT, although the total number of antimicrobial treatments required to treat sick calves ( P = 0.78) and the mortality rate ( P = 0.99) were not affected by supplemental fat. Feeding +FAT diet tended ( P ≤ 0.09) to increase plasma concentration of cortisol and immunoglobulin-G compared to –FAT. In summary, feeding 30% roughage diets or adding 3.5% yellow grease (DM basis) as supplemental fat increased G:F during the feedlot receiving period. Abstract : Supplementing 3.5% of yellow grease to receiving feedlot calves increased gain:feed. Lay Summary: The low intake of feed that beef calves exhibit during the first weeks after feedlot arrival results in inadequate nutrient intake, especially energy, which leads to low rates of gain and decreased immune function and likely increases the risks for respiratory diseases. Increasing the energy density of receiving diets (Mcal/kg of dry matter) could result in increased energy intake of newly received finishing cattle. In this experiment, we evaluated the effects of two roughage levels (wheat hay at 30% [R30] or 60% [R60]; dry matter [DM] basis) combined with two levels of supplemental fat (yellow grease at 0% [−FAT; no supplemental fat] or 3.5% [+FAT]; DM basis). Calves-fed R30 tended to have greater average daily gain and final body weight than calves-fed R60. Gain efficiency (gain:feed ratio; G:F) was greater for calves-fed R30 than calves-fed R60. Feeding +FAT tended to increase average daily gain compared to −FAT diet, and G:F was greater for calves-fed +FAT than −FAT. In summary, feeding 30% roughage diets or adding 3.5% of yellow grease increased G:F during the feedlot receiving period, with minimal impact on morbidity rate from respiratory disease.