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.

The present study was designed to determine the effect of barn or cycle of grazing on changes of biochemical metabolites in prepartum and changes of milk composition in postpartum of dairy cows. For this purpose, a total of sixteen 25 months old Holstein primiparous dairy cows were allocated in two groups (n=8) with an average body weight of 571.61 ± 35.30 kg (Barn) and 578.10 ± 39.20 kg (Grazing). The study was conducted from June 2018 to October 2018. Results revealed that barn raised dairy cows had a higher increase in their serum albumin and calcium level on day 14 prepartum. However, the level of palmitic acid, saturated fatty acid increased significantly, and the level of fat, oleic acid, γ-linoleic acid, arachidonic acid and unsaturated fatty acids decreased significantly in barn raised dairy cow’s milk on day 14 postpartum. There were no significant differences observed with respect to all other biochemical metabolites, fatty acids and minerals between barn raised and cycle grazing dairy cows during prepartum and postpartum. Our study results could serve to a better understanding of barn raised cow with respect to changes of biochemical metabolites in prepartum and changes of milk composition, fatty acids and minerals content in grazing dairy cows in postpartum for estimating their physiological status.

In this study, the effect of daily short-distance walking exercise on milk production and metabolic status of the lactating dairy cows was investigated. The experiment was conducted with 10 lactating dairy cows comprising 2 groups (5 dairy cows/group), which were walking activity and non-walking activity. The walking activity (WA) group lactating dairy cows walked outdoors for 1 km/d, and the non-walking activity (non-WA) lactating dairy cows were maintained within a cowshed from 18thApril to30th May. The activity volume of the neck was not significantly different between the groups, but the activity volume of the leg was higher in WA group compared with non-WA (p<0.05). The rectal temperature was higher in the WA group (38.6 ℃) compared with non-WA (38.2 ℃) (p<0.05). No significant differences in dietary NE intake, milk production and milk composition were found between the groups. The plasma cortisol concentration was higher in WA group (2.14 μg/dl) compared to non-WA (0.95 μg/dl) (p<0.05). However, plasma cortisol level of WA dairy cows was significantly decreased as compared with non-WA cows. On the contrary, the level of plasma melatonin was increased in WA cows than that of non-WA dairy cows. It may be interpreted as a change in physical fitness. From this study, we suggest that walking activity can be improved energy balance. Further investigation is needed to determine whether different combinations of distance, rate or doing in morning or afternoon will stimulate energy balance.

The objective of this research was to evaluate the effects of two different feeding systems on blood metabolites in Holstein heifers and analyze the economic impacts of the feeding systems. The following two experiments were conducted to investigate the effects of feeding system on blood metabolite changes in Holstein heifers and analyze the economic impacts of the two systems. In experiment 1, the effects of two different feeding systems on cortisol, progesterone, and estradiol in Holstein heifers were examined. In experiment 2, the effects of two different feeding systems on the body weights of Holstein heifers and profitability of the two feeding systems were studied. Results showed that the pasture-raised heifers showed significantly decrease in the levels of blood cortisol (p<0.05) and increases in the levels of progesterone and estradiol (p>0.05) when compared with heifers raised in indoor feeding system. The average daily gain was significantly higher (p<0.05) in indoor-raised heifers (0.73 kg/day) as compared to pasture-raised heifers (0.58 kg/day). Also, 25.2% more profits were obtained from the pasture feeding system as compared to the indoor feeding system. These results together would be useful in the investigation of feeding system and growth performance in dairy cattle.

An experiment was carried out to determine the homofermentative activity of Lactobacillus plantarum KCC-10 and KCC-19 on the ensiling of whole crop barley (WCB). The crude protein in the silages was slightly higher in the KCC-10 and KCC-19 treatments compared to the control, but there was no significant difference between the two inoculant-treated silages. Nutrient parameters such as acid detergent fiber, neutral detergent fiber and in vitro dry matter digestibility in L. plantarum KCC-10 and KCC-19 treated silages did not differ from those in the control silage. The lactic acid content increased in KCC-10 and KCC-19 treated silage when compared with the control silage but the contents of acetic acid and butyric acid produced in KCC-10 and KCC-19 treated silages were similar with the control silage. Further, the number of lactic acid bacteria (LAB) in KCC-10 treated silage demonstrated a significant increase when compared to the control. Especially, KCC-19 treated silage showed greater lactic acid bacterial growth potential. Other microbes such as yeast and fungi were not detected in KCC-10 and KCC-19 treated WCB silages. Hence, this study suggests that the addition of L. Plantarum KCC-10 and KCC-19 to the WCB silage can improve fermentation quality for the production of high-quality silage.

An investigation was carried out to evaluate the potential role of Lactobacillus Plantarum KCC-10 and KCC-19 on the quality and fermentation characterization of Italian ryegrass (IRG) silages. The physiochemical properties of IRG silage such as crude protein content, neutral detergent fiber, acid detergent fiber, total digestible nutrient and in vitro dry matter digestibility were not affected by KCC-10 and KCC-19. The pH of IRG silage in KCC-10 and KCC-19 treatments decreased compared to the control (p<0.05), while the lactic acid content in KCC-10 and KCC-19 treatments increased compared to the control (p<0.05). In addition, the number of lactic acid bacteria (LAB) in the KCC-10 treatment increased compared to the control (p<0.05). The number of lactic acid bacteria in KCC-19 increased, but there was no significant difference in all treatments. Therefore, we recommend L. plantarum KCC-10 and KCC-19 as potential additive candidates in IRG silage with lots of advantages.