INVESTIGATION OF FACTORS AFFECTING COLOSTRUM QUALITY IN HOLSTEIN COWS UNDER STANDARDIZED CONDITIONS

The success of colostral passive immune transfer; The quality of the colostrum used in feeding can be affected by factors such as the amount, method of administration, and time of administration. Colostrum quality is determined by the amount of Ig it contains. Especially the amount of IgG in colostrum constitutes 85% of Ig in colostrum. The amount of colostral Ig varies depending on many variables, these are maternal race, colostrum amount obtained at first milking and total colostrum volume secreted, calving season, maternal age, maternal diseases, prepartum feeding and drying time, applied vaccines and drugs, colostrum leakage from the prenatal udder and time between birth and first milking. In this study, the effects of calf birth weight, sex, single-twin birth, dystocia, age, and lactation number on colostrum quality were investigated when external variables such as breed, season, maintenance conditions, dry period feeding, dry period, vaccination were eliminated in a single farm. The animal material of this study consisted of 183 Holstein cows of different ages, which gave birth in November- December 2022, in an enterprise located in Ankara. The business has established modern maintenance and feeding standards and trained its staff on technical issues. Dry period and lactation periods are standardized. In the study, colostrum quality was determined by measuring the total protein level and using a brix refractometer, which is based on the principle of indirect determination of the Ig level. When evaluating the results: the brix 22% value was accepted as equivalent to 50 g/L Ig density, which is considered the limit of good-quality colostrum, and below this value was classified as poor-quality colostrum. Before proceeding to the statistical analysis, the variables were evaluated in terms of parametric test assumptions. Descriptive statistics were calculated for qualitative and quantitative variables. Differences in colostrum quality in the groups of the difficult delivery score and the number of lactations were calculated with a one-way analysis of variance. Duncan's test was used as an advanced test in cases where there was significance. In addition, the difference in colostrum quality between single/twin birth and gender groups was analyzed by Student's t-test. The relationship between calf birth weight, the number of lactations, the age of the cow, average milk yield, and colostrum quality was determined using the Pearson correlation coefficient. P<0.05 was accepted as the limit of significance. All statistical analyzes were performed using the IBM SPSS 23.0 statistical program. The brix value of 183 Holstein cows added to the study group was found to be over 22%. In the study performed, no significant difference was found in terms of difficulty birth score, single/twin birth, and colostrum quality in gender groups (p>0.05). A weak negative correlation was determined between colostrum quality, number of lactations, and cow's age (p<0.05). This shows that colostrum quality decreases as the number of lactations and the age of the cow increase. When the number of lactations was examined in the correlation, it was determined that there were significant differences. When lactation numbers were grouped, it was observed that colostrum quality was higher in the first lactation and decreased as the number of lactations increased.