Lipid Metabolism, Carcass Characteristics and Longissimus dorsi Muscle Fatty Acid Composition of Tropical Crossbred Beef Cattle in Response to Desmanthus spp. Forage Backgrounding

Abstract

Lipid metabolism, carcass characteristics and fatty acid (FA) composition of the Longissimus dorsi (loin eye) muscle were evaluated in tropical crossbred steers backgrounded on Desmanthus spp. (desmanthus) with or without feedlot finishing. It was hypothesized that steers backgrounded on isonitrogenous diets augmented with incremental proportions of desmanthus will produce carcasses with similar characteristics and FA composition. Forty-eight Brahman, Charbray and Droughtmaster crossbred beef steers were backgrounded for 140 days on Rhodes grass (Chloris gayana) hay augmented with 0, 15, 30 or 45 percent desmanthus on dry matter basis. Lucerne (Medicago sativa) hay was added to the 0, 15 and 30 percent desmanthus diets to ensure that they were isonitrogenous with the 45 percent desmanthus diet. After backgrounding, the two heaviest steers in each pen were slaughtered and the rest were finished in the feedlot for 95 days before slaughter. Muscle biopsy samples were taken at the beginning and end of the backgrounding phase. Carcasses were sampled at slaughter for intramuscular fat (IMF) content, fat melting point (FMP) and FA composition analyses. Increasing the proportion of desmanthus in the diet led to a linear increase in docosanoic acid (p = 0.04) and omega-6/omega-3 polyunsaturated FA ratio (n-6/n-3 PUFA; p = 0.01), while docosahexaenoic acid decreased linearly (p = 0.01). Feedlot finishing increased hot carcass weight, subcutaneous fat depth at the P8 site and dressing percentage (p ≤ 0.04). The n-6/n-3 PUFA ratio was within the recommended < 5 for human diets. IMF was within the consumer-preferred ≥3% level for palatability. The hypothesis that steers backgrounded on isonitrogenous diets augmented with incremental proportions of desmanthus will produce similar carcass characteristics and FA composition was accepted. These findings indicate that a combination of tropical beef cattle backgrounding on desmanthus augmented forage and short-term feedlot finishing produces healthy and highly palatable meat.

Fortification of diets with omega-3 long-chain polyunsaturated fatty acids enhances feedlot performance, intramuscular fat content, fat melting point, and carcass characteristics of Tattykeel Australian White MARGRA lambs

“…The FMP was determined as described by Mwangi et al ( 28 ) and Pewan et al ( 29 ). Briefly, the muscle samples were placed in an oven at 100°C for 1–2 min to obtain fat that was used for FMP determination.…”

Effects of forage type on the rumen microbiota, growth performance, carcass traits, and meat quality in fattening goats

“…Finishing beef are often fed a forage-based diet in order to improve omega-3 polyunsaturated fatty acids, conjugated linoleic acid, and superior nutritional value ( 13 ). Similarly, in goats, mixed orchard hays can increase beneficial fatty acids and amino acids of meat, suggesting that feeding suitable type of forage is an important strategy for producing high-quality meat ( 14 ).…”

Genetics and nutrition impacts on herd productivity in the Northern Australian beef cattle production cycle

“…2021a ; Peel, 2003 ; Thomson & White, 2006 ). Backgrounding nutrition strategies support frame and muscle development as opposed to fattening ( Mwangi et al. 2021b ), and facilitate year-round supply of stocker cattle to feedlots ( Gaughan et al., 2018 ; Groves, 2020 ).…”

“… Bowen and Chudleigh (2021a) suggested key strategies for improving and sustaining extensive livestock production systems that are drought resilient and more profitable across northern Australia's beef enterprises. These include drought-preparedness ( Rolfe et al., 2021 ), optimal steer sale age, breeder body condition and herd structure, effective phosphorus supplementation ( Bowen et al., 2020 ) and improvement in steer nutrition through tropically adapted perennial legume grass pastures ( Mwangi et al., 2021a ; Mwangi et al., 2021b ). Fordyce et al., (2021) defined the primary business measure of liveweight production for beef cows in northern Australia and reported that liveweight production in breeding beef cows was primarily governed by available nutrition and mating outcome.…”