Carcass and meat quality of young Angus steers with different growth potential finished exclusively grass-fed or corn supplemented.

Beef cattle production has a large variety of systems with different performance and technology levels. This study compared young Angus steers carcass and meat quality traits of high growth potential early-finished animals fed exclusively on pasture with low growth potential late-finished animals. Besides the grazed forage, the low growth potential group received corn grain at 0.8% of their body weight right after the slaughtering of the first group. Following weaning, the 20 steers grazed pastures composed of oat, ryegrass, and clovers. At winter's onset, animals were moved to native pastures improved with fescue and clovers. The supplemented period of late steers began when the first group of ten early-finished animals reached the requirements for slaughter. Supplementation ended when the animals got the slaughter requirements. The high growth potential steers showed a ribeye area (P < 0.0001) and a Longissimus muscle width highly significantly (P < 0.0001) superior to the low growth group. However, corn-supplemented animals showed better dressing percentage (P < 0.0001), subcutaneous fat thickness (P < 0.0001), marbling (P < 0.0001), and muscle (P = 0.0033) scores, but lower shear force (P = 0.0001). The finishing system did impact fat lightness (L*; P = 0.0234) at the slaughter time. Grass-fed animals showed higher red-green color parameter (a*) values than corn supplemented on fat at 24 h (P = 0.0439) but lower hue angle (P = 0.0418). The consumer panel showed better results for tenderness and general acceptability for supplemented animals beef compared to grass-fed. The supplementation resulted in a higher carcass standardization. It also provided higher PUFA: MUFA and n-6: n-3 ratios, and a higher amount of n-3. Supplemental corn grain did not have adverse effects upon the beneficial effects to human health of the grass-fed beef.

Sire effects on carcass and meat quality traits of young Nellore bulls.

Meat quality is being increasingly demanded by consumers in recent years. Several factors can affect meat quality, ranging from animal traits such as breed and genetic heritage to pre- and post-slaughter processes. This study investigated the influence of Nellore bulls on carcass and meat quality traits. We used 475 young uncastrated males, the progeny of 54 bulls, to evaluate characteristics of the following carcass traits: hot carcass weight, rib-eye area, and fat thickness. We also evaluated the following beef quality traits: marbling, color, drip loss, cooking loss, and shear force at 0, 7, and 14 days of aging. Bulls had a significant influence (P≤0.05) on rib-eye area, fat thickness, marbling, drip loss at 14 days of aging and color at all aging periods. Based on these results, the use of bulls with high breeding values for these traits can provide important advances in carcass traits and meat quality in breeding programs of Nellore cattle that are raised in tropical conditions.

Association of single nucleotide polymorphisms in the bovine leptin and leptin receptor genes with growth and ultrasound carcass traits in Nellore cattle.

Given the important role of leptin in metabolism, we looked for a possible association of leptin and leptin receptor polymorphisms with carcass and growth traits in Nellore cattle. We examined associations of leptin and leptin receptor SNPs with ultrasound carcass (longissimus dorsi muscle area (ribeye area), backfat thickness and rump fat thickness and growth traits (weaning weight adjusted to 210 days of age, yearling weight adjusted to 550 days of age, weight gain of weaning to yearling and scrotal circumference adjusted to 550 days of age) of 2162 Bos primigenius indicus (Nellore) animals. Allele and genotypic frequencies were calculated for each marker. Allele substitution, additive and dominance effects of the polymorphisms were also evaluated. Some alleles of the molecular markers had low frequencies, lower than 1%, in the sample analyzed, although the same polymorphisms described for B. p. taurus cattle were found. Due to very low allelic frequencies, the E2JW, A59V and UASMS2 markers were not included in the analysis, because they were almost fixed. E2FB was found to be significantly associated with weight gain, ribeye area and backfat thickness. The promoter region markers, C963T and UASMS1, were also found to be significantly associated with ribeye area. T945M was significantly associated with weight gain. We conclude that the leptin and receptor gene markers would be useful for marker-assisted selection.

Single nucleotide polymorphisms in CAPN and leptin genes associated with meat color and tenderness in Nellore cattle.

We analyzed single nucleotide polymorphisms in calpain, leptin, leptin receptor, and growth hormone receptor genes and their association with color, drip and cooking losses of longissimus muscle at 7, 14 and 21 days postmortem in 638 purebred Nellore bulls slaughtered between 22 and 26 months of age. Meat samples were vacuum-packed and aged at 4°C. The single nucleotide polymorphisms T945M, GHR2, E2FB, and CAPN4751 were evaluated. All genotypic classes were observed; however, the T/T genotype of T945M and E2FB was found at a low frequency. A significant association of E2FB with drip loss (a measure of water-holding capacity) was detected at seven days of meat aging. CAPN4751 had an additive effect on red and yellow color intensities. The T allele of CAPN4751 was found to be positively associated with improved meat color, but not with meat tenderness, differing from a previous report indicating that it is associated with meat tenderness. We conclude that the potential for use of CAPN4751 as a marker for these meat quality traits requires further research.

Genetic parameters for postweaning traits in Braunvieh cattle.

Genetic parameters for traits related to postweaning growth in Braunvieh cattle, reared under tropical and sub-tropical conditions in Brazil, were studied. Weight traits were weight at 365 days of age (W365, N = 4055), at 450 days (W450, N = 3453), and at 550 days (W550, N = 1946), while weight gains were gain from weaning to 365 days of age (WGW365, N = 3060), from weaning to 450 days (WGW450, N = 2764), from weaning to 550 days (WGW550, N = 1531), from 365 to 550 days of age (WG365550, N = 1528), from 365 to 450 days (WG365450, N = 2401), and from 450 to 550 days (WG450550, N = 1563). A full animal model was used for estimating the variance components, using the MTDFREML software. The dataset contained 18,688 animals with phenotypic measures and 35,188 animals in the relationship matrix. Heritability estimates for postweaning weights decreased with age. For W365, W450 and W550, respectively, the direct heritability estimates were 0.29 +/- 0.061, 0.25 +/- 0.057, 0.16 +/- 0.060, maternal heritability was 0.20 +/- 0.035, 0.18 +/- 0.035, 0.13 +/- 0.052, and total heritability was 0.30, 0.35, 0.26. In this breed, maternal influence was found to be important up to 550 days of age. The greater genetic correlations between weights were observed for weights measured at shorter intervals. A large environmental effect was observed for weight gain between weaning and 550 days; this effect was greater for the gains between 365 and 550 days.

Genetic parameters for pre-weaning traits in Braunvieh cattle.

The objective of this study was to estimate genetic parameters for pre-weaning traits of Braunvieh cattle raised under tropical conditions in Brazil. The weight and weight gain parameters were birth weight (BW, N = 9955), weight at 120 days of age (W120, N = 5901), weaning weight at 205 days (WW, N = 6970), weight gain from birth to 205 days (GAIN205, N = 6013), weight gain from birth to 120 days (GAIN120, N = 5135), and weight gain from 120 to 205 days (GAIN85, N = 4482). Variance components were estimated using the animal model with the MTDFREML software. The relationship matrix included 35,188 animals; phenotypic measures were available for 18,688. Direct and maternal heritability increased from birth to weaning, with estimates of 0.23 +/- 0.037, 0.25+/- 0.050, 0.41+/- 0.059 for direct heritability for BW, W120 and WW, respectively, 0.08 +/- 0.012, 0.15 +/- 0.032, 0.22 +/- 0.036 for maternal genetic effects, and 0.18, 0.14 and 0.16 for total heritability estimates. For pre-weaning gains, estimates of heritability were 0.36 +/- 0.059, 0.30+/- 0.059, 0.12 +/- 0.035 for direct genetic effects of the traits GAIN205, GAIN120 and GAIN85, respectively, 0.23 +/- 0.038, 0.17 +/- 0.037, 0.03 +/- 0.029 for estimates of maternal heritability, and 0.12, 0.13, 0.16 for total heritability, respectively. Genetic correlations between weights were greater between measures taken at shorter intervals. This information can be used to optimize the design of programs for genetic improvement of Braunvieh cattle raised under tropical conditions.