Identification of Monoallelically Expressed Genes Associated with Economic Traits in Hanwoo (Korean Native Cattle)

Hanwoo, an indigenous Korean cattle breed, has been genetically improved by selecting superior sires called Korean-proven bulls. However, cows still contribute half of the genetic stock of their offspring, and allelic-specific expressed genes have potential, as selective targets of cows, to enhance genetic gain. The aim of this study is to identify genes that have MAEs based on both the genome and transcriptome and to estimate their effects on breeding values (BVs) for economically important traits in Hanwoo. We generated resequencing data for the parents and RNA-sequencing data for the muscle, fat, and brain tissues of the offspring. A total of 3801 heterozygous single nucleotide polymorphisms (SNPs) in offspring were identified and they were located in 1569 genes. Only 14 genes showed MAE (seven expressing maternal alleles and seven expressing paternal alleles). Tissue-specific MAE was observed, and LANCL1 showed maternal allele expression across all tissues. MAE genes were enriched for the biological process of cell death and angiogenesis, which included ACKR3 and PDCL3 genes, whose SNPs were significantly associated with BVs of lean meat production-related traits, such as weight at 12 months of age, carcass weight, and loin eye area. In the current study, monoallelically expressed genes were identified in various adult tissues and these genes were associated with genetic capacity in Hanwoo.

PSII-B-25 Age-related changes in growth hormone-insulin like growth factor 1 axis-regulating factors and metabolic hormones in Korean cattle steer

Meat yield is important for beef industry for maximum profits. Enhancing muscle growth by promoting hypertrophy of muscle fiber is required for increasing meat yield. Growth hormone (GH)-insulin like growth factor 1 (IGF1) axis and metabolic hormones have a central role for regulating hypertrophy of muscle fiber. We investigated age-related changes in GH-IGF1 axis-regulating factors and metabolic hormones in beef cattle. Ten Korean cattle steers were used. The longissimus thoracis (LT) samples were biopsied between the 11th and 12th rib at 12, 18, and 24 months of age. Steers were slaughtered at 34 month of age and the LT samples were collected. The LT samples were used for histological observation of muscle fiber size and detection of mRNA levels by real-time PCR analysis. Blood was collected at 12, 18, 24, and 34 months of age and used for hormone analyses. The mean muscle fiber size increased (P < 0.01) from 12 to 24 months, and remained unchanged at 34 months. Plasma GH concentrations were unchanged with age, whereas circulating IGF-1 concentrations decreased (P < 0.001) with age. Testosterone and insulin concentrations increased from 12 to 24 months and remained unchanged at 34 months. Leptin concentrations were unchanged from 12 to 24 months and increased at 34 months. The mRNA levels of growth hormone receptor (GHR) and signal transducer and activator of transcription 5a/b (STAT5a/b) decreased (P < 0.01) from 12 to 24 months, whereas mRNA levels of IGF-1 gene increased (P < 0.001) with age. Results indicate that the increased muscle fiber size in LT from 12 to 24 months are characterized with increasing concentrations of circulating testosterone and insulin. Age-dependent changes in muscle fiber hypertrophy were also related with changes in GHR, STAT5a/b, IGF-1 mRNA levels in the LT.

PSXI-13 Effects of pasture grazing on growth performance and blood composition of Hanwoo steer during the growing stage

This study investigated the effect of pasture grazing on growth performance and blood characteristics in nine-month-old Hanwoo (native Korean cattle) steers. Thirty one steers were randomly assigned to three groups: (CON) Italian ryegrass and concentrate (1.6% BW) until 14 month of age, (G1) pasture grazing 101 days without concentrate, (G2) pasture grazing 101 days and concentrate (1.6% BW). Initial BW of CON, G1 and G2 were 255 kg, 238 kg and 254kg respectively. Average daily gains were higher in CON (1.02 kg) and G2 (0.92 kg) than G1 (0.62 kg) (p >0.05). Final weight and total weight gain were higher in the feeding concentrate (1.6% BW) groups (Con and G2) compared to the G1. Blood characteristics, such as such as total cholesterol (T-CHO), triglycerides (TG) and non-esterified fatty acid (NEFA) were investigated to test the effects on health and energy metabolism. T-CHO, an index of fat metabolism and liver function, was lower in Con (119.75 md/dL) and G2 (107.13md/dL) than G1 (87.79 mg/dL). TG was higher in Con (21.63 IU/L) than G1(15.14 IU/L) (P< 0.08). NEFA was higher in G2 (384 uEq/L) than other groups (Con 138 uEq/L and G1 225 uEq/L). These results show that concentrates supplementation during grazing period is needed to increase BW of Hanwoo steer in the growing state.

PSXV-24 Effects of dietary beet pulp on growth performance, beef quality, rumen fermentation characteristics, and blood parameters in Korean cattle steers

We investigated the effects of feeding beet pulp (BP) instead of corn flake (CF) on growth performance, beef quality, ruminal fermentation, and blood parameters in Korean cattle steers. Eighteen Korean cattle steers (body weight, 732 ± 12.6 kg; age, 31.2 ± 0.16 months) were divided into the CF and BP groups. The approximately 92% of dry matter of the requirement was offered as a concentrate portion, and the 8% was offered as an oat straw. The 85% of concentrate portion was provided by the pelleted basal concentrate, and the remaining 15% with CF or BP for 12 weeks. Average daily gain, feed efficiency, and carcass traits were not affected by feeding BP. The proportion of ruminal iso-butyrate (P = 0.004), iso-valerate (P = 0.001), and valerate (P = 0.01) were lower in the BP group compared to the CF group. Blood glucose (P = 0.06) and non-esterified fatty acids (P = 0.09) concentrations tended to be higher in the BP group than in the CF group. The results suggest that BP could be a good energy source without affecting the growth performance and beef quality in Korean cattle steers.

GPS Coordinates for Modelling Correlated Herd Effects in Genomic Prediction Models Applied to Hanwoo Beef Cattle

It is widely known that the environment influences phenotypic expression and that its effects must be accounted for in genetic evaluation programs. The most used method to account for environmental effects is to add herd and contemporary group to the model. Although generally informative, the herd effect treats different farms as independent units. However, if two farms are located physically close to each other, they potentially share correlated environmental factors. We introduce a method to model herd effects that uses the physical distances between farms based on the Global Positioning System (GPS) coordinates as a proxy for the correlation matrix of these effects that aims to account for similarities and differences between farms due to environmental factors. A population of Hanwoo Korean cattle was used to evaluate the impact of modelling herd effects as correlated, in comparison to assuming the farms as completely independent units, on the variance components and genomic prediction. The main result was an increase in the reliabilities of the predicted genomic breeding values compared to reliabilities obtained with traditional models (across four traits evaluated, reliabilities of prediction presented increases that ranged from 0.05 ± 0.01 to 0.33 ± 0.03), suggesting that these models may overestimate heritabilities. Although little to no significant gain was obtained in phenotypic prediction, the increased reliability of the predicted genomic breeding values is of practical relevance for genetic evaluation programs.