Under the practical conditions, it is important to evaluate the factors affecting milk performance. Data from test day yield and milk components should be useful for such evaluation. The aim of the experiment was to study the effect of season, udder health (by somatic cell counts SCC), parity, stage of lactation on milk production, milk components, and SCC under the practical conditions. Also, the frequency of incidence of high SCC during the season was observed. The experiment was realized on one dairy farm in dairy practice. The experiment lasted from December 2015 to October 2017. We examined 481 Holstein dairy cows (6910 milk samples). Milk samples were collected once per month – performed by recording test day. Only cows with 9 – 11 test days were evaluated. The effect of season, parity, stage of lactation, and SCC influenced most of the studied traits. The milk yield was highest at 2nd lactation. In the following lactations, the milk yields were decreasing. The SCC significantly increased with advanced parity. The elevated SCC was found in the beginning and in the final part of lactation. SCC as a factor significantly reduced milk yield, lactose content but increased fat and protein content. In conclusion, under practical conditions, the management should use the data from test days and analyze them for a better understanding of the performance efficiency at the farm level and for implementing more sophisticated decision making in farming.
The aim of the review was to provide information about the importance of iodine in human nutrition and to review milk as an important source of iodine, and also to summarize the main factors affecting iodine concentration in milk. Iodine is an essential element for the thyroid gland function and synthesis of thyroid hormones, which regulate key processes of metabolism, brain development and growth. Therefore, it is important to ensure adequate, neither deficient nor excessive, intake of this element in animal nutrition, but more importantly in the nutrition of humans. Milk and dairy products are very valuable sources of iodine. However, its concentration in milk is very variable, as it is affected by many different factors – iodine intake in feed, antinutritional factors, iodine species (forms) used for feeding, animal keeping, farm management and possibly also milk yield. Additionally, milk iodine concentration is also affected by teat dipping with iodine disinfection, and by milk processing (e.g. skimming and heat treatment). All these aforementioned factors may possibly play their role in improving human nutrition, especially the nutrition of pregnant, lactating women, and people on a low-salt diet who are the most vulnerable to insufficient iodine intake.
The purpose of the study was to asses the effect of calving season and dams' parity on milk yield and gestation length of dairy cows. We examined 93 animals of Slovak spotted breed from the farm located in western Slovakia (Lower Váh region), in years 2014-2017. The herds' average 305-d milk yield was 8,133 ±1,380 kg. The calving season was divided into four categories: spring (March to May), summer (June to August), autumn (September to November) and winter (December to February). The factor of dams parity was divided into 4 groups: 1 st parity cows, 2 nd-3 rd parity cows, 4 th and higher parity cows. Calving season affected significantly milk yield of dairy cows (P <0.01). The highest 305-d milk production was oberved in winter calvings (8,942 ±218 kg) and the lowest in spring calvings (7,377 ±287 kg). The gestation length was not signifficantly altered by calving season (P >0.32). Dams' parity was not significantly affected by 305-d milk yield (P >0.22). Nevertheless, the animals on the 4 th and higher lactation were numerically more productive (8,481 ±259 kg) compared to the dairy cows on their 1 st , 2 nd-3 rd lactation (8,123 ±264 kg; 7,884 ±223 kg; resp.). The dams' parity significantly affected gestation length (P <0.02), with the shortest gestation length in 1 st parity dams (278 ±2 days) and the longest gestation in 2 nd-3 rd parity dams (284 ±1 days).To sum up, our results suggest significant role of calving season in relation to milk yield and significant effect of dams' parity on gestation length.
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