KOREASCHOLAR

The objective of the present study was to determine the best model to describe and quantify the changes in live body weight, height at withers, height at rump, body length and chest girth of Holstein cows raised under Korean feeding conditions for 50 months. The five standard growth models namely polynomial linear regression models, regression of growth variables on the first and second-order of ages in days (model 1) and regression of growth variables on age covariates from first to the third-order (model 2) as well as non-linear models were fitted and evaluated for representing growth pattern of Holstein cows raised in Korean feeding circumstances. Nonlinear models fitted were three exponential growth curve models; Brody, Gompertz, and von Bertalanffy functional models. For this purpose, a total of 22 Holstein cows raised in Korea used in the period from April 2016 to May 2020. Each model fitted to monthly growth curve records of dairy cows by using PROC NLIN procedure in SAS program. On the basis of the results, nonlinear models showed the lower root mean square of error (RMSE) for live body weight, height at withers, height at rump, body length and chest girth (12.22, 1.95, 1.55, 4.04, 2.06) with higher correlation coefficiency (R2) values for live body weight, height at withers, height at rump, body length and chest girth (0.99, 0.99, 0.99, 1.00, 1.00). Overall, the evaluation of the different growth models indicated that the Gompertz model used in the study seemed to be the most appropriate one for standard growth of Holstein cows raised under Korean feeding system.

ABSTRACT
Ⅰ. INTRODUCTION
Ⅱ. MATERIALS AND METHODS
    1. Animal feeds and feeding
    2. Growth models
    3. Statistical analysis
Ⅲ. RESULTS AND DISCUSSION
Ⅳ. CONCLUSION
Ⅴ. ACKNOWLEDGEMENT
Ⅵ. REFERENCES

• Mayakrishnan Vijayakumar(Dairy Science Division, National Institute of Animal Science, Rural Development Administration)
• Yun-Ho Choy(Animal Breeding and Genetics Division, National Institute of Animal Science, Rural Development Administration)
• Tae-Il Kim(Dairy Science Division, National Institute of Animal Science, Rural Development Administration)
• Dong-Hyun Lim(Dairy Science Division, National Institute of Animal Science, Rural Development Administration)
• Seong-Min Park(Dairy Science Division, National Institute of Animal Science, Rural Development Administration)
• Mahboob Alam(Animal Breeding and Genetics Division, National Institute of Animal Science, Rural Development Administration)
• Hee-Chul Choi(Dairy Science Division, National Institute of Animal Science, Rural Development Administration)
• Kwang-Seok Ki(Dairy Science Division, National Institute of Animal Science, Rural Development Administration)
• Hyun-Jeong Lee(Dairy Science Division, National Institute of Animal Science, Rural Development Administration) Corresponding author