Effect of weaning strategy and backgrounding management on growth performance, carcass characteristics, and mRNA expression in the longissimus muscle of beef steers

We evaluate the effect of the weaning strategy (WS; early, 130 ± 21 d vs. normal, 187 ± 20 d) and backgrounding management (BGM) on growth, carcass characteristics, and relative mRNA expression in the longissimus muscle (LM) of beef steers. One hundred and twenty Angus × SimAngus-crossbred steers (body weight (BW) = 130 ± 11.2 kg) were used in a randomized complete block design. Steers, blocked by age and BW, were randomly assigned to one treatment (2 × 2 factorial). Treatments consisted of early weaned (EW) or normal weaned (NW) steers subsequently backgrounded (BG) on either a forage-based (FB) or concentrates-based (CB) diet. The EW steers (d 0) were ad libitum-fed a grain-based diet for 49 d until nursing calves were NW. Steers were ad libitum-fed either a FB diet for 214 d or a CB diet for 95 d afterward. Steers were finished on a high-grain diet until harvested at an estimated constant 12th-rib fat thickness (1.5 cm). Expression of mRNA in the LM was measured over time. Data were analyzed using PROC MIXED in SAS. The EW steers were heavier (P ˂ 0.01) at the beginning of the backgrounding and finishing period. When the finishing phase began, steers FB were heavier (P ˂ 0.01) than CB steers. There was a tendency for a WS × BGM interaction (P = 0.08) for final BW, where NW-FB steers were heavier than the steers on the other three treatments, which do not differ between them. In the finishing phase, steers BG on a FB diet had greater dry matter intake and average daily gain, but lower gain-to-feed ratio (P ˂ 0.01). There was a WS × BGM interaction (P = 0.03) for days on feed (DOF) in the finishing diet, where backgrounding steers in a FB diet decreased DOF required to reach the harvesting target among EW steers, but not within NW steers. No interactions or treatment effects (P ≥ 0.17) were detected for marbling score (MS). For ZFP423, EW steers showed a greater mRNA expression on d 112 and a lower expression on d 255 than NW steers (P ˂ 0.01). In d 57, steers BG on a CB diet presented a greater delta-like homolog 1 mRNA expression than steers BG on a FB diet, whereas in d 255, this was inverted (P ˂ 0.01). For CCAAT/enhancer binding protein D (C/EBPD) mRNA expression, a tendency for a WS × BGM interaction was observed (P = 0.06), where a greater expression of C/EBPD was observed in steers BG on a FB diet among EW steers, but not within NW steers. In this study, early grain feeding followed by different BGM does not support MS improvements of beef carcasses.

Effects of calcium salts of palm oil inclusion and ad libitum feeding regimen on growth performance, carcass characteristics, and plasma glucose-dependent insulinotropic polypeptide concentration of feedlot steers

Sixty Angus × SimAngus-crossbred steers (body weight [BW] 279 ± 16 kg) were used to evaluate the effect of calcium salts of palm oil inclusion (CPO) and the amount of feed offered (AFO) on plasma glucose-dependent insulinotropic polypeptide (GIP) concentration and its association with energy metabolism and marbling score (MS) in feedlot steers. Steers were blocked by BW and gain to feed (G:F) and randomly assigned to individual feedlot pens. Treatments (2 × 2 factorial) consisted of ad libitum-fed steers without (ANF) or with (AWF) the inclusion of CPO or restricted-fed steers (85% of the ad libitum intake of ANF) without (RNF) or with the inclusion of CPO (RWF). After weaning, steers were adapted to individual pens and fed a corn silage-based diet for 30 d and subsequently placed in a ground corn (GC)-based diet. Diets were given ad libitum or at 85% of the ANF intake and with or without CPO. After 59 d on the finishing diet, all steers had ad libitum access to the finishing diet until harvest. Measurements of CO2 emission and O2 consumption to estimate respiratory quotient (RQ) were taken (n = 9/treatment). Correlations between plasma GIP and insulin concentrations and RQ were analyzed. A linear regression was performed to evaluate the association of plasma GIP and MS. All data were analyzed using the PROC MIXED procedure of SAS. During the first 103 d of the trial, there were AFO × CPO interactions (P ≤ 0.01) for BW, dry matter intake (DMI), average daily gain (ADG), and net energy for maintenance (NEm) intake. Ad libitum-fed steers without CPO presented the greatest DMI among dietary treatments and had greater BW and ADG compared with steers in the RWF and RNF treatments. After all steers had ad libitum access to dietary treatments, steers that were previously restricted showed a 30% and 19% increase (P ≤ 0.01) in ADG and G:F, respectively. There was a three-way interaction time × CPO × AFO (P = 0.04) for plasma GIP concentration. There was no correlation (P = 0.96) of GIP with RQ, whereas insulin demonstrated marginal significance for a positive (P = 0.07) and negative (P = 0.08) correlation with plasma GIP and RQ, respectively. There was no association (P = 0.30) between GIP and MS. These data indicate that GIP secretion results from an interaction between CPO and energy intake depending on the time relative to feed intake that GIP might indirectly regulate energy metabolism through insulin secretion, and that GIP does not appear to be associated with MS.

Effect of Hemi-Castration on the Productivity, Histological Characteristics, and Economic Efficacy of Korean Beef Cattle

We evaluated the growth performance, serum testosterone, carcass traits, histological characteristics, and economic efficacy of castrated and hemi-castrated Korean beef cattle. Thirty-two Hanwoo calves (Initial body weight: 148.4 ± 19.8 kg) were randomly assigned into the castrated Hanwoo (CH) and hemi-castrated Hanwoo (HH) group. The experiment lasted 18 months; the animals were all slaughtered on the same day. Final body weight and average daily gain (ADG) tended to increase in the HH group compared to the CH group. Testosterone concentration was higher in HH group (5.27-14.27 ng/dL) than in the CH group (0.47-0.70 ng/dL) during the whole experimental period after castration (p < 0.05). Rib eye area was 17.08 cm² wider in HH group than in CH group, but marbling score was improved by 3.33 in CH group compared to HH group (p < 0.01). Deposition area of adipocytes in Longissimus dorsi were higher in CH group than in HH group (p < 0.001). Net income per head was 1760 US dollar higher in the CH group than in the HH group (p < 0.04). Thus, our findings suggest that hemi-castration had positive effects on the increase in ADG and meat yield traits, with negative effects on marbling and profitability.

Genetic Analysis of Major Carcass Traits of Korean Hanwoo Males Raised for Thirty Months

Simple Summary

Generally, Korean Hanwoo males produced under a 24-month production cycle (PROD24) are evaluated as a part of the progeny test program. However, there is little information on other males outside the PROD24, such as those raised under a 30-month production cycle (PROD30) for higher profits. Therefore, we investigated PROD30 males for important carcass traits (carcass weight, eye muscle area, backfat thickness, and marbling score) using a reasonably large dataset to understand their genetic merit. To do so, we estimated the genetic parameters of traits using animal model. Our analysis revealed moderate to high heritability values for the studied traits. The marbling score was found to be highly heritable at 0.56. The genetic correlation between traits was mostly moderate to low, and the backfat thickness was poorly correlated with the marbling score. These results are consistent with many previous reports on PROD24. Our study suggests that PROD30 and PROD24 males might have somewhat similar genetic potential, as well as similar genetic backgrounds. Thus, it could be concluded that there is further scope for PROD30 males to improve Hanwoo males’ overall prediction accuracy, especially under a genomic selection program, together with PROD24 males.

Abstract

Understanding animals’ genetic potential for carcass traits is the key to genetic improvements in any beef cattle. In this study, we investigated the genetic merits of carcass traits using Hanwoo males raised in a 30-month production system (PROD30). We achieved this using a dataset comprising 6092 Hanwoo males born between 2005 and 2017 and measures of four carcass traits (carcass weight, CWT; eye muscle area, EMA; backfat thickness, BFT; and marbling score, MS). Genetic parameters were estimated using a multiple-trait animal model through the AIREMLF90 program. According to the multiple-trait model, the h² of CWT, EMA, BFT, and MS were 0.35 ± 0.04, 0.43 ± 0.05, 0.48 ± 0.05, and 0.56 ± 0.05, respectively. The strongest genetic correlation (r_g) was obtained between CWT and EMA (0.49 ± 0.07), whereas it was negligible between CWT and BFT. EMA and MS were also moderately correlated, whereas there was a relatively low negative correlation between EMA and BFT (−0.26 ± 0.08). Our study revealed a consistent indirect genetic improvement in animals from 2005 onwards. Although Hanwoo improvement has mainly focused on males under a 24-month production cycle, we observed PROD30 males to have somewhat similar genetic potential. Our results provide useful insights into the genetic merits of PROD30 males for the first time, which may facilitate future studies on them and their integration into the Hanwoo National Evaluation for genomic selection.

Genome-Wide Association Study of Meat Quality Traits in a Three-Way Crossbred Commercial Pig Population

Meat quality is an important trait for pig-breeding programs aiming to meet consumers' demands. Geneticists must improve meat quality based on their understanding of the underlying genetic mechanisms. Previous studies showed that most meat-quality indicators were low-to-moderate heritability traits; therefore, improving meat quality using conventional techniques remains a challenge. Here, we performed a genome-wide association study of meat-quality traits using the GeneSeek Porcine SNP50K BeadChip in 582 crossbred Duroc × (Landrace × Yorkshire) commercial pigs (249 males and 333 females). Meat conductivity, marbling score, moisture, meat color, pH, and intramuscular fat (IMF) content were investigated. The genome-wide association study was performed using both fixed and random model Circulating Probability Unification (FarmCPU) and a mixed linear model (MLM) with the rMVP software. The genomic heritability of the studied traits ranged from 0.13 ± 0.07 to 0.55 ± 0.08 for conductivity and meat color, respectively. Thirty-two single-nucleotide polymorphisms (SNPs) were identified for meat quality in the crossbred pigs using both FarmCPU and MLM. Among the detected SNPs, five, nine, seven, four, six, and five were significantly associated with conductivity, IMF, marbling score, meat color, moisture, and pH, respectively. Several candidate genes for meat quality were identified in the detected genomic regions. These findings will contribute to the ongoing improvement of meat quality, meeting consumer demands and improving the economic outlook for the swine industry.

Distribution of the variant at AKIRIN2: c.*188G > A in Chinese cattle

Marbling score (MS), is an economically important trait in cattle. Previous results showed that a SNP (c.*188G > A) of akirin 2 (AKIRIN2) gene was associated with MS in Japanese Black cattle and Korean cattle. However, the distribution of the genotypic frequency of the single nucleotide polymorphism (SNP) has not been explored in Chinese cattle. In this study, we used polymerase chain reaction (PCR) and DNA sequencing to detect the variation in 1296 individuals from 39 Chinese cattle breeds, one semi-wild bovine species (Dulong) and three introduced breeds (Angus, Holstein and Brahman). Our study found the frequency of the A allele at this locus roughly diminished from north to south in Chinese cattle, and we detected statistically significant differences between Angus and Brahman (p < 0.05), Dulong and another two breeds (Angus and Holstein; p < 0.01) using Chi-Square Independence Test. Our results reflected the variation of AKIRIN2: c.*188G > A in Chinese cattle, which would help us better understand Chinese cattle genetic resources and provide reference for further research.

Genetic analysis of carcass and meat quality traits in Nelore cattle1

The objective of this study was to estimate genetic parameters for carcass and meat quality traits, as well as their genetic correlations using pedigree and genomic information. A total of 3,716; 3,702; 3,439; 3,705; and 3,714 records of 12th-13th rib LM area (LMA), backfat thickness (BF), HCW, marbling score (MARB), and Warner-Bratzler peak shear force (WBSF), respectively, were used. Animals were genotyped with BovineHD BeadChip and GeneSeek Genomic Profiler Indicus HD - GGP75Ki panel. The (co)variance components were estimated by Bayesian inference using a multitrait ssGBLUP analysis. The animal model included fixed effects of contemporary group (defined by the combination of farm and year of birth, and management group at yearling) and age of animal at slaughtering as a covariate (linear). Direct additive genetic and residual effects were fitted as random. The posterior means and SD of heritabilities for LMA, BF, HCW, MARB, and WBSF were 0.28 (0.03), 0.21 (0.04), 0.21 (0.04), 0.12 (0.04), and 0.11 (0.03), respectively. The posterior means for genetic correlations between LMA and meat quality were positive and moderate with MARB (0.38 ± 0.12) and negative with WBSF (-0.47 ± 0.12). Low genetic correlations were estimated between BF and WBSF (-0.03 ± 0.16) and between HCW and MARB (-0.04 ± 0.14), indicating that these traits are not controlled by the same set or linked genes. Carcass traits (LMA, BF, and HCW) presented moderate heritability providing quick response to the selection purpose. The estimates of heritability for meat quality traits (MARB and WBSF) were low and indicate that the rate of genetic improvement for these traits would be slow. Genetic correlations indicated that selection for carcass traits would not be strongly antagonistic for improving meat quality.

Multiple Regression Analysis to Estimate the Unit Price of Hanwoo (Bos taurus coreanae) Beef

This study were estimated the contribution of carcass traits to unit price, to analyze the marbling score as a categorical variable rather than a numerical variable, and to develop an optimal model that also includes the holiday effect and the raising period. The data for this study were acquired from the Quality Evaluation of the Korea Institute for Animal Products, and consisted of the trading records of 1,613,699 heads at 12 wholesale markets from 2010 to 2014. The unit price of a cow was estimated from the following parameters: −52.50 Won/mm, 8.93 Won/cm², 7.20 Won/kg, and −1.04 Won/day for backfat thickness, eye muscle area, carcass weight, and raising period, respectively. Parameters for the dummy variables of marbling scores varied from 0 to 8328.74 Won/kg, which means that each marbling score grade had a different price value. The unit price of a steer was estimated from the following parameters: −92.12 Won/mm, 20.22 Won/cm², 1.30 Won/kg, and −1.72 Won/day for backfat thickness, eye muscle area, carcass weights, and raising period, respectively. Parameters for dummy variables of marbling scores varied from 0 to 7338.80 Won/kg, which means that the grades of each marbling score had different price values. The unit price of sales during traditional holidays was significantly higher (827.71 Won/kg for cows, and 645.15 Won/kg for steers) than during non-holidays.We conclude that the use of categorical values for marbling scores would be needed to evaluate the price of Hanwoo beef using multiple regression analysis based on carcass traits and environmental factors.

Factors influencing the priority of access to food and their effects on the carcass traits for Japanese Black (Wagyu) cattle

The factors influencing the priority of access to food and the effects of the priority of access to food on their carcass traits were analyzed for Japanese Black (Wagyu) cattle in a semi-intensive fattening production system. The records of 96 clinically healthy steers and heifers were analyzed. The calves at ∼3 to 4 months of age were allocated to pens with four animals per pen; all four animals in the same pen were of the same sex and of similar body size. The ranking of the animals' priority of access to food (1st, 2nd, 3rd and 4th), which was determined by the farm manager, was used as an indicator of social dominance in the present study. Four models including sire line, maternal grandsire line and the difference in the animals' birth dates as fixed effects were used to analyze factors influencing the priority of access to food. Ranking was represented by ordinal scores (highest=4, lowest=1) in Model 1, and the binary scores were assigned in Model 2 (highest=1; 2nd, 3rd and 4th=0), Model 3 (1st and 2nd=1; 3rd and 4th=0) and Model 4 (1st, 2nd and 3rd=1; lowest=0). The results showed that the difference in the animals' birth dates had a significant effect on the establishment of the priority of access to food in Model 3 (P<0.05), suggesting that animals born earlier may become more dominant in the pen. The maternal grandsire line tended to affect the social rank score in Models 2 and 3 (P<0.10). Our results indicated that the maternal grandsire line may affect the temperament of calves through their mothers' genetic performance and thereby more aggressive calves may be more dominant and have higher priority of access to food. On the other hand, there was a significant effect of the priority of access to food on beef marbling score (BMS; P<0.05), and the priority of access to food also tended to influence the carcass weight (P=0.09). The highest BMS was observed for animals with the first rank of the priority of access to food (P<0.05), and the higher-ranking animals had the tendency to be heavier carcass than the lower-ranking animals. Our findings emphasized the importance of information about the priority of access to food determined by farmers' own observation on implementing best management practices in small-scaled semi-intensive beef cattle production systems.

Genetic association of marbling score with intragenic nucleotide variants at selection signals of the bovine genome

Selection signals of Korean cattle might be attributed largely to artificial selection for meat quality. Rapidly increased intragenic markers of newly annotated genes in the bovine genome would help overcome limited findings of genetic markers associated with meat quality at the selection signals in a previous study. The present study examined genetic associations of marbling score (MS) with intragenic nucleotide variants at selection signals of Korean cattle. A total of 39 092 nucleotide variants of 407 Korean cattle were utilized in the association analysis. A total of 129 variants were selected within newly annotated genes in the bovine genome. Their genetic associations were analyzed using the mixed model with random polygenic effects based on identical-by-state genetic relationships among animals in order to control for spurious associations produced by population structure. Genetic associations of MS were found (P<3.88×10-4) with six intragenic nucleotide variants on bovine autosomes 3 (cache domain containing 1, CACHD1), 5 (like-glycosyltransferase, LARGE), 16 (cell division cycle 42 binding protein kinase alpha, CDC42BPA) and 21 (snurportin 1, SNUPN; protein tyrosine phosphatase, non-receptor type 9, PTPN9; chondroitin sulfate proteoglycan 4, CSPG4). In particular, the genetic associations with CDC42BPA and LARGE were confirmed using an independent data set of Korean cattle. The results implied that allele frequencies of functional variants and their proximity variants have been augmented by directional selection for greater MS and remain selection signals in the bovine genome. Further studies of fine mapping would be useful to incorporate favorable alleles in marker-assisted selection for MS of Korean cattle.

Genetic parameters for sensory traits in longissimus muscle and their associations with tenderness, marbling score, and intramuscular fat in Angus cattle

The objective of this study was to estimate heritabilities for sensory traits and genetic correlations among sensory traits and with marbling score (MS), Warner-Bratzler shear force (WBSF), and intramuscular fat content (IMFC). Samples of LM from 2,285 Angus cattle were obtained and fabricated into steaks for laboratory analysis and 1,720 steaks were analyzed by a trained sensory panel. Restricted maximum likelihood procedures were used to obtain estimates of variance and covariance components under a multitrait animal model. Estimates of heritability for MS, IMFC, WBSF, tenderness, juiciness, and connective tissue traits were 0.67, 0.38, 0.19, 0.18, 0.06, and 0.25, respectively. The genetic correlations of MS with tenderness, juiciness, and connective tissue were estimated to be 0.57 ± 0.14, 1.00 ± 0.17, and 0.49 ± 0.13, all positive and strong. Estimated genetic correlations of IMFC with tenderness, juiciness, and connective tissue were 0.56 ± 0.16, 1.00 ± 0.21, and 0.50 ± 0.15, respectively. The genetic correlations of WBSF with tenderness, juiciness, and connective tissue were all favorable and estimated to be -0.99 ± 0.08, -0.33 ± 0.30 and -0.99 ± 0.07, respectively. Strong and positive genetic correlations were estimated between tenderness and juiciness (0.54 ± 0.28) and between connective tissue and juiciness (0.58 ± 0.26). In general, genetic correlations were large and favorable, which indicated that strong relationships exist and similar gene and gene networks may control MS, IMFC, and juiciness or WBSF, panel tenderness, and connective tissue. The results from this study confirm that MS currently used in selection breeding programs has positive genetic correlations with tenderness and juiciness and, therefore, is an effective indicator trait for the improvement of tenderness and juiciness in beef. This study also indicated that a more objective measure, particularly WBSF, a trait not easy to improve through phenotypic selection, is an excellent candidate trait for genomic selection aimed at improving eating satisfaction.

Association of a single nucleotide polymorphism in the akirin 2 gene with economically important traits in Korean native cattle

The akirin 2 gene, located on chromosome 9 in cattle, was previously reported to be associated with nuclear factor-kappa B (NF-κB), involved in immune reactions and marbling of meat. To determine whether a single nucleotide polymorphism (SNP) in akirin 2 is associated with economically important traits of Korean native cattle, the c.*188G>A SNP DNA marker in the 3'-UTR region of akirin 2 was analyzed for its association with carcass weight, longissimus muscle area and marbling. The c.*188G>A SNP was genotyped by polymerase chain reaction restriction fragment length polymorphism, and the frequency of the AA, AG, and GG genotypes were 6.82%, 71.29% and 21.88% respectively. This SNP was significantly associated with longissimus muscle area (Bonferroni corrected P < 0.05), and marbling score (Bonferroni corrected P < 0.01). These results suggest that the c.*188G>A SNP of akirin 2 might be useful as a DNA marker for longissimus muscle area and marbling scores in Korean native cattle.