We researched the influence of two methods of housing primiparous cows on meeting estimated energy requirements. In herd A primiparous cows were kept in a separate technological group during the whole lactation period, whereas in herd B they were kept in technological groups together with multigravid cows. The whole herd A consisted of 400 cows, where the average annual yield was 10,200 kg of milk per cow. Herd B consisted of 250 cows, where the average annual yield was 8,500 kg of milk per cow. In 2010 and 2011 there were 200 primiparous cows in herd A, whereas in herd B there were 165 primiparous cows. The milk yield for 100 and 305 days of lactation was analysed. Meeting the cows' demand for energy was determined on the basis of the percentage of protein in milk. In both herds primiparous cows were divided into milk yield classes for 100 days of lactation. Both the trend and the amount of variation in the content of protein in milk were found to be identical in both herds. The content of protein in milk increased as the milk yield decreased. This regularity could be observed at both lactation stages under analysis and the differences between the classes were statistically confirmed. During the first 100 days of lactation the estimated energy deficit comprised a much larger percentage of the cows than in the 305-day lactation period. The system of maintenance of primiparous cows (separately or together with multigravid cows) was not found to influence the milk yield or the estimated demand for energy.
The aim of the study was to determine factors influencing the balance of energy and protein in high-yielding cows. Daily milk yield, lactation number and month of lactation were analysed. The study was carried out in a herd with yield of 11,000 kg milk/year, on 517 lactating cows. The cows were divided into four feeding groups. They were fed TMR calculated for levels of milk production, as follows: group 1 – for 45 kg, group 2 – for 35 kg, group 3 – for 26 kg and group 4 – for 20 kg. The actual mean milk yield for these groups was 49.1 kg, 38.1 kg, 26.3 kg and 17.5 kg per day. Each group consisted of cows in their first to sixth lactation and in their first to tenth month of lactation. No significant differences were noted in daily milk yield between lactation numbers or months of lactation. As milk yield increased in the groups, the content of fat and protein decreased. The estimated balance of energy, based on the protein percentage in the milk, was negative for nearly the entire lactation in group 1, for the first four months of lactation in group 2, for the first two months in group 3, and in the second month of lactation for group 4. Group 1 was divided into three subgroups according to yield: up to 45 kg, 45-50 kg and 50 kg or more. Energy was estimated to be wellbalanced only in the first subgroup. The balance of energy in the cows was strongly determined by daily milk yield, and to a lesser degree by the month of lactation. Protein, based on the concentration of urea in the milk, was well-balanced in groups 1 and 2. In groups 3 and 4, the recommended level of protein in the rations was exceeded by 10-20%.
Abstract. A study was conducted on the effect of separated manure as bedding material on milk quality as manifested in the somatic cell count. Cows were maintained in a loose barn in cubicles bedded with fresh separated cattle manure (SCM) with 40 % solids content. Analyses were conducted on 242 primiparous Polish Black and White Holstein-Friesian cows in the course of a 305-day lactation. Mean milk yield in that period amounted to over 9000 kg per cow. Somatic cell counts, daily milk yields and chemical composition of milk were analysed. Data were obtained from analyses of 2324 milk samples. It was found that 93.3 % of samples contained less than 400 000 somatic cells per 1 mL milk. Approximately 4.3 % of milk samples contained the number of somatic cells indicating subclinical mastitis (200 000 cells mL−1), while in 2.4 % it was clinical mastitis (> 800 000 cells mL−1). The incidence rate for both forms of mastitis was similar in the beginning and at the end of lactation. Mean daily milk yield of cows producing milk classified according to quality (SCC) grades 1 (< 25 000 cells mL−1) and 2 (< 25 000; 50 000 > cells mL−1) was statistically significantly greater than the yields of other cows. For analysed milk constituents a relationship was found between SCC classes and contents of milk fat and solids. Conducted analyses showed that SCM as bedding in cow cubicles had no effect on somatic cell counts in milk of primiparous cows. The study was conducted in a single holding, in one lactation, on cows calving in 2014.
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