Background and Aim: Colostrum composition and importance for newborn organisms were repeatedly studied. However, the interest in transitional milk usefulness is weak and recommendations concerning transition milk intake are not developed. The aim of this study was to evaluate whether transition milk intake after colostrum consumption affects the chances of calf infection with Cryptosporidium spp. Materials and Methods: We collected data for Cryptosporidium spp. infection from calves (n=425) divided into three groups: The first group – supervised colostrum and transition milk intake; the second group – supervised colostrum and whole milk intake; and the third group – not supervised colostrum and whole milk intake. To detect oocysts of Cryptosporidium spp. in feces, the flotation method was used, and slides were stained using the modified Ziehl-Neelsen method. Generalized linear mixed modeling was conducted to determine whether the explanatory variable – the management of colostrum and transition milk feeding with three categories (three research groups) – was related to the probability of calves incurring infection with Cryptosporidium spp. Results: In the first group, 26.1% of calves were positive for the presence of Cryptosporidium spp. oocysts, in the second – 37.2%, and in the third – 44.1%. Statistical data analysis showed that calves who did not receive transition milk after colostrum consumption had increased chances of having Cryptosporidium spp. (by 1.90-2.47 times on average). The main results showed that the management of colostrum and transition milk feeding is related to Cryptosporidium spp. infection, indicating that both colostrum and transitional milk play a significant role in controlling pathogenic infections. Conclusion: The most effective management of colostrum and transition milk feeding against Cryptosporidium spp. infection is the timely intake of an adequate amount of colostrum followed by transitional milk consumption for at least 2 weeks before weaning from the dam.

The effect of colostrum on calves’ health status was intensively studied, while the role of transition milk was left underestimated. The common practice is to feed calves with an adequate amount of colostrum immediately after calving and soon after feeding calves are weaned from dams. In this research, calves were not weaned from dams for at least 2 weeks receiving both colostrum and transition milk on demand. Thus, we have recreated natural feeding conditions for calves’ development. We used a stratified sample method to test whether the size of the dairy cattle farms, breed, parity number, season of calving, and length of the dry period affect the likelihood of calves’ infection with Cryptosporidium spp. considering these factors influence both colostrum and transition milk quality. The main results showed that 26.1% of calves were positive for the presence of Cryptosporidium spp. oocysts. The presence of clinical signs of diarrhea was recorded in 15% of the positive animals. Regression analysis showed that multiparous cows decrease the chance of calves to have Cryptosporidium spp. by 82%–89%, while cows calved on small farms decrease the chance of calves to have Cryptosporidium spp. by 80%. We suggest that primiparous cows are spending inner resources primarily on their maturation, thereby leaving the prerequisites for the infection of their offspring, while intense farming just increases the chance of unprotected calves to obtain infections.