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The effect of the light period on milk yield and fertility of dairy cows
VRBOVÁ, Aneta
The main objective of the study was to ascertain fertility and milk productivity of dairy cows raised under the conditions of modern technology in the context of micro-climactic features and the quality of housing. The observation occurred from 1. 1. 2013 to 31. 12. 2014 in Cooperative Farm Pluhův Žďár and 150 dairy cows of the Holstein cattle were observed. The program Statistica 12 (StatSoft?) was used to evaluate observed values. Data characterisation was conducted through the use of descriptive statistics, and, furthermore, a correlation analysis and a chi-square test were used. During the evaluation of the micro-climate of the stables, it was detected that the average temperatures of the environment shifted from 7.90 °C to 27.03 °C. Relative humidity was measured in the range of 73.44 % and 86.84 %. THI achieved values from 45,11 to 68.93. The milk yield correlated negatively with the temperature during autumn months (r = - 0.377) and a negative correlation was also found in relation to the relative humidity (r = - 0.356) and a similar relation existed between the THI and the milk yield (r = - 0.409). The influence of the length of the photoperiod on milk productivity showed itself to be positive in the cases of all groups of observed dairy cows. The group of cows at the 1st lactation increased milk productivity by 4.7 % the cows at the 2nd lactation showed an increase of milk productivity by 12.6 % and the dairy cows at the 3rd and further lactations provided an increase of milk yield of 18 %. The influence of the length of the photoperiod on conception was not statistically conclusive (p = 0.100), but there was a tendency pointing to worse conception results when automatic lighting was used as opposed to when the natural photoperiod was used. With the temperature on the day of conception taken into consideration, the rate of conception ranged between 27 % and 51 % in the periods of 24 and 48 hours before insemination. There was a tendency of a better conception in the group of primiparous cows in the temperature range over 15.1 °C in comparison with the group of cows at the 2nd and further lactations. The influence of the temperature of the environment on conception after first insemination 24 and 48 hours before the insemination itself was statistically conclusive (p < 0.05). A positive influence of an extended photoperiod on rumination was found among all groups of observed dairy cows. The dairy cows at the 1st lactation increased their ruminative activity by 42 minutes and the group of older cows by 25 minutes in 24 hours. The greatest difference between these two groups was observed during the winter months (XII-II), during which time the dairy cows ruminated longer by 21.7 % on average in comparison with the natural photoperiod (p < 0.001).
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Vyhodnocení mléčné užitkovosti vybraného chovu koz
KRAPKOVÁ, Adéla
The aim of this diploma thesis is to asses the effect of various factors on the milk production and its content in regard to goat's milk in the years 2015 to 2017. The evaluation was conducted on goat farm Richmond Stars in Chotětov. The farm currently accommodates 31 goats of the white shorthaired breed. They are still opting for the one rectangular space solution. The feeds consist of bulk fodder, silage, hay and grass (pasture during summer). The feed composure is the same throughout the whole year. The water supply system consists of water containers with manual refill. The goats are divided into groups based on their age. Milking takes place twice a day. The data on milk production was processed using Microsoft Excel and Statistica. When comparing the overall milk productivity with the average of Czech Republic, there were statistically significant differences found in the fat content in the year 2016, in the protein content in years 2015, 2016 and 2017, in the lactose content in the year 2015. In all cases, the Richmond Stars farm was the one with better score. Other results were evaluated as inconclusive and therefore no statistically significant difference was found. When considering the impact of the goat's age on the milk productivity and the goat's milk content, there was a statistically conclusive impact in the productivity (milking) itself as well as in the fat content. When observing the impact of the father-line on the productivity level and the milk content, there was a statistically conclusive result only in the fat content. When evaluating the impact of the period of birth on the milk productivity and milk content, there was a statistically conclusive impact on the fat and lactose content. All other results, specifically the productivity (milking), were evaluated as inconclusive and therefore were not statistically significant for the purpose of evaluation of the milk productivity characteristics.
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Porovnání mléčné užitkovosti genotypů českého strakatého a holštýnského skotu chovaných ve stejných podmínkách
NOVÁKOVÁ, Hana
The basic prerequisite to the economic prosperity of an agricultural company specializing in dairy cows is maximum production of milk and, by extension, dairy by-products at minimal production costs. In order to achieve that it is necessary to have dairy cows with the potential to reach optimal dairy production in the conditions of the given agricultural company. The objective of this paper is to assess the effect of genotype, lactation sequence, and age of the dairy cow at first calving on the parameters of her milk productivity. Our monitoring was conducted at a company named CIZ-AGRO, a. s., Cizkrajov. For our analysis, we used productivity data measured from October 2012 to February 2015, during which the cows ended at least one lactation period lasting 240 305 days. These input parameters were collected from a total of 495 dairy cows that had ended a total of 997 lactations. The compilation of lactations was subsequently sorted out by genotype and lactation sequence, and thereupon by genotype and age of the dairy cows at first calving. Thus classified groups were assessed by average milk production, dairy fat, milk protein per lactation, and percentage content of fat and protein in their milk. The obtained results were thereupon subjected to a statistical analysis. The highest average milk productivity per lactation (9283 liters) was achieved by dairy cows in the group H100 that calved first at the age of over 27 months; the lowest milk (6239.2 liters) was recorded with a C100 heifer. In the group classified by lactation sequence, the differences were not statistically significant, the groups classified by the age at first calving, the differences were less significant statistically (P<0.05). Evaluation of the percentage content of milk components as well as the overall production of milk components per lactation in the group of lactations classified by genotype and lactation sequence, there were no statistically significant differences between the individual groups identified. In the group of lactations classified by genotype and age at first calving, the result showed less significant differences (P<0.05) between the group evaluated by total milk fat productivity and milk protein content per lactation. Monitoring the percentage content of fat in the milk in relation to the genotype and age of the dairy cow at first calving recorded medium level of statistically significant differences between the groups (P<0.01).
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