BACKGROUND: Mastitis could be detected in various ways, including physical, on-farm, and laboratory tests. OBJECTIVES: The present research aimed to evaluate the accuracy of the diagnosis of mastitis using lactate dehydrogenase (LDH)-based dipsticks and to assess these dipsticks with regard to the effects of different lactation days, the amount of milk production, and parity. RESULTS: Considering bacteriologic culture as a gold standard method for the diagnosis of subclinical mastitis, the sensitivity and specificity of LDH test were 68.9 % and 54 %, respectively. The results revealed a high correlation between SCC and LDH. A statistically significant relationship was observed between the response of dipstick and CMT results; with the increase in the CMT score, the score of LDH dipstick increased. By investigating the effects of lactation days, the amount of milk production, and parity, it was determined that the chance of having subclinical mastitis in cows with positive dipstick result was 5.59 times greater than that in cows with negative dipstick result. There were no significant relationships among SCC, LDH, and CMT with lactation days and milk production; meanwhile, with the increase in parity, the three above-mentioned variables showed significant increase. CONCLUSIONS: The results of the present study indicated that the best methods for subclinical mastitis detection were SCC, CMT, and LDH based dipsticks, respectively.

Aim of the present study was to determine the effect of the lactation number on milk production and to detect the most economical lactation period in Holstein dairy cows. Materials and The animal materials of the study were 392 Holstein dairy cows with a similar dry period and lactation length. The cows were divided into 6 groups according to the number of lactations. The groups were formed as 1st lactation (Group 1; n=67), 2nd lactation (Group 2; n=124), 3rd lactation (Group 3; n=51), 4th lactation (Group 4; n=62), 5th lactation (Group 5; n=41) and 6th lactation (Group 6; n=47).Average lactation milk yields for the 1st, 2nd, 3rd, 4th, 5th, and 6th lactations of the cows used in the study were 7860.03 kg, 9010.02 kg, 10207.15 kg, 10165.89 kg, 8430.57 kg and 8069.78 kg, respectively. It was determined that the highest milk production and highest daily income were obtained during the 3rd and 4th lactation periods (p<0.05).In conclusion, milk production increased in the first three lactations, 3 and 4 lactation remained stable and decreased in 5th and 6th lactations. But, regardless of the number of lactations during the first 6 lactation periods, it is considered economical to use healthy cows for milk production in dairy farms.

Information on the nutritional content of animal feed is very important in improving milk production and the quality of milk produced. Data on the nutrition and nutritional quality of feed given to livestock are not comprehensively evaluated and recorded in any dairy farms in Johore. The objective of this study is to determine the nutritional content of selected feedstuffs, with production and quality of milk in selected dairy farms in Johore. Data were collected from 94 dairy farms during field visits through face-toface interviews. Feed samples collected were dairy cattle pellet, Napier grass, palm kernel cake, palm kernel expeller, soybean hull, corn, cassava peel and agricultural waste. Proximate analysis was performed using standard AOAC methods. The result of this study found that 67.0% of dairy farmers in Johore use Napier grass as the main source of fodder. The survey showed that 46% of the farmers in Johore give a suitable quantity of Napier grass based on body weight, while for milk production, the survey showed that 54 dairy farms in Johore produce less than 100 litres/day, 18 farms produce 101-200 litres/day, 12 farms produce 201-300 litres/day, and 10 farms produce more than 300 litres/day. The overall status of dairy farms in Johore shows that 60% of the farms produce an average of 5.1-10 litre milk per cow per day in which 92.5% of milk samples collected had acceptable Total Dissolved Solid values indicating good quality of milk production.