Effect of grain feeding on fat colour and other carcass characteristics in previously grass-fed Bos indicus steers

Abstract

One hundred Brahman cross steers were Subcutaneous fat depth at 105 and 175 days (17.3 mm) removed from pasture and fed a high grain diet for a was greater than at 35 and 70 days (14.5 mm) and finishing period of 0, 35, 70, 105, or 175 days. The significantly (P<0.05) greater than at the initial steers were then slaughtered and assessed for slaughter (12.5 mm). subcutaneous fat depth, fat colour, meat colour, Fat colour was correlated (in the subcutaneous and marbling, and p-carotene and lutein concentrations in intermuscular fat, respectively) with p-carotene the fat and serum.(r = 0.61 and 0.55) and lutein (r = 0.53 and 0.52) The average liveweight gain was 0.7 kg/day. After concentrations, and in the serum, with p-carotene 35 days of grain feeding, fat colour was significantly (r = 0.49) concentration. Objective assessment of fat (Pc0.05) decreased from 3.9 to 2.4 when assessed using colour, the Minolta b* value, was also correlated (in the grading chips ranging from 0 (polar white) to 9 (creamy subcutaneous and intermuscular fat, respectively) with yellow). There was a trend to a further decline in fat p-carotene (r = 0.85 and 0.80) and lutein (r = 0.74 and colour over longer finishing periods (1.7 at 105 days 0.73) concentrations and was correlated with p-carotene and 2.0 at 175 days), although 1 steer had a fat colour (r = 0.61) concentrations in the serum. It was score of 6 at 70 days and 1 at 105 days slaughter, and demonstrated that grain feeding had an effect on another had a score of 4 at 175 days. Steers fed for changing bovine fat colour, and although p-carotene was 175 days had higher marbling but darker meat than predominant in serum, both p-carotene and lutein those fed for the other finishing periods (P<0.05). contributed to the yellowness in bovine carcass fat.

Genetic variation in fatness and fatty acid composition of crossbred cattle1

“…The study by Strachen et al (1993) supports this observation by reporting that with Australian Bos indicus steers, fat color score was reduced from 3.9 to 2.4 after only 35 d of grain feeding. Because most cohorts only gained 1 mm P8 fat per month (not reported), but presumably entered the feedlot with fat color scores equivalent to the 1997 steers, it appeared that β-carotene was being removed from the fat in addition to simply being diluted by fattening.…”

Effect of dietary vitamin A on plasma and liver carotenoid concentrations and fat colour in Angus and Angus crossbred cattle

“…This may be because the PC concentration was too high to allow further loss of carotenoids or there was a non-labile pool of carotenoids in the fat. The changes in the carotenoid concentration in the fat were similar to those found by Forrest (1981) but contrast with those found by Seiner et al (1992) and Strachan et al (1993), who found fat carotenoid concentration decreased for 97-105 days in steers fed low carotenoid diets. In contrast to these results, Yang et al (1993) found no decreases in the carotenoid concentration in subcutaneous fat or the objectively measured fat colour in steers fed a low carotenoid diet for 56 days, despite the serum carotenoid concentration decreasing to 0.4 291 Carotenoid concentrations in plasma and fat, and fat colour in the cattle in Experiments 1-3, were higher than reported by Australian workers.…”

“…However, at the end of the feedlot period their cattle had blood carotenoid concentrations of 0.1-0.8 ng/ml which were similar to the concentration in Experiment 3. The carotenoid concentration in subcutaneous fat of 1.6 ± 0.1 |ag/g after steers were on the feedlot for 112 days in Experiment 3 was similar to the 1.09-1.41 ug/g found for cattle before they entered feedlots in Australia (Strachan et al 1993;. Their steers had subcutaneous fat carotenoid concentrations of 0.29 ± 0.02 jxg/g after 105 days on a feedlot.…”

“…In contrast to these results, Yang et al (1993) found no decreases in the carotenoid concentration in subcutaneous fat or the objectively measured fat colour in steers fed a low carotenoid diet for 56 days, despite the serum carotenoid concentration decreasing to 0.4 291 Carotenoid concentrations in plasma and fat, and fat colour in the cattle in Experiments 1-3, were higher than reported by Australian workers. They found blood carotenoid concentrations of 2.3-2.6 ug/ml in cattle entering their feedlots (Yang et al 1992;Yang et al 1993;Seiner et al 1992;Strachan et al 1993) compared with 7.4 ± 0.4 ug/ ml for cattle in Experiment 3. However, at the end of the feedlot period their cattle had blood carotenoid concentrations of 0.1-0.8 ng/ml which were similar to the concentration in Experiment 3.…”

Effects of forage‐ and grain‐based feeding systems on beef quality: A review

“…Fat colour is related to the genotype, sex, and age of the animal, as well as its diet (Pearson 1966;Morgan & Everitt 1969;Walker et al 1990). Cattle absorb carotenoids from their diet and deposit them into adipose tissue (Yang et al 1992), and since grains contain low levels of carotenoids (compared with fresh pasture) it is not surprising that as the amount of grain in the ration of pasture-fed beef increases, or the duration of grain-feeding increases, the yellow pigmentation of fat declines (Craig et al 1959;Forrest 1981;Walker et al 1990;Strachan et al 1993). Davis et al (1981) found that even when the intake of grain-fed steers was restricted so that they would grow at the same rate as pasture-fed steers, grain-feeding for 111-125 days still produced whiter fat.…”