Influence of Phenotypic Factors on the Productivity of Cows and Somatic Cells Content in Milk
Abstract: Викладено результати впливу фенотипових факторів на молочну продуктивність корів та показники якості молока, зокрема вміст соматичних клітин. Встановлено вірогідний вплив віку тварини, стадії лактації, сезону року та оператора машинного доїння на фізико-хімічні показники молока та захворювання корів на мастит.Проаналізовано більше 15 тисяч проб молока та виявлено, що середній вміст соматичних клітин у молоці був досить високим -411±7 тис у см 3 За отриманими даними біля 20 % досліджених проб молока були отрима… Show more
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Introduction. Numerous studies of domestic scientists testify to the sometimes significant, but multidirectional influence of the year and season of calving and birth on the formation of milk productivity and other economically useful traits. In our previous studies, it was established that at the population level, among the mentioned environmental factors, the most significant influence on the phenotypic variability of the milk productivity of first-calf heifers is caused by the herd (15–22%), the year of the first calving (4.7–12%) and birth (4.2–12%), the lowest is the season of birth (0.05–0.2%) and calving (1.5–2.1%). A number of other researchers report a higher influence of the herd and the year and a smaller one of the calving season and especially the birth on the milk productivity of first-calf heifers. In our opinion, the phenotypic manifestation of signs of milk productivity in different herds is influenced by different levels of breeding and feeding, technological solutions of cow keeping and milking systems. Research materials and methods. The research was carried out on farms breeding Ukrainian Red dairy cattle of LLC "Nova Niva" of the Donetsk region. The materials of the electronic information database in the DCMS ORSEK format as of October 11, 2021 were used. In controlled animals, the intensity of growth of live weight by growing periods up to one and a half years of age, live weight at 18 months, age of first calving, length of the service period, coefficient of reproductive ability between the first and second carvings, fertility and output of milk fat and protein for the first 305 days three and higher lactation. Research results. On average, during the entire accounting period, the level of rearing of heifers up to a year ensured average daily gains in live weight at the level of almost 600 g, and at the age of 12 to 18 months – more than 550 g. Thus, the live weight of heifers and heifers at the age of one and a half practically met the standard of the Ukrainian Red dairy breed. The age of the first calving reached almost 27.9 months, which corresponded to the optimal recommendations at the time of the research (27 months). In general, the first-calf heifers under control were characterized by a relatively low reproductive ability. The duration of the service period is 72 days or 90% longer than the optimum (80 days). Univariate variance analysis established an almost equal share of the influence of the year of birth and calving factors on the studied characteristics of cows. The year of birth determines from 12.6 to 68.6% of the total phenotypic variability, the year of the first calving – from 12.5 to 70.4% with a high degree of significance. The year factor has a 1.5–2 times greater influence on live weight gains of heifers up to a year old than at the age of 12–18 months. The influence of the year of birth is 10% greater than that of the year of the first calving. The factor of the season of birth (0.1–2.3%) and calving (0.2–2.7) exerts a much smaller influence on the variability of the investigated traits. The influence of seasonal environmental factors on the growth of live weight of heifers and the age of first calving turned out to be somewhat higher. On the signs of milk productivity, seasonal fluctuations in environmental conditions show a low, but reliable influence only during the first lactation. During the second and older lactations, this effect is practically leveled off to an unreliable level of statistical significance. In most cases, intergroup differentiation was higher between years of birth than between years of first calving. In our opinion, this is caused by a higher impact on the productivity of different levels of cultivation in chronologically and naturally climatically different economic years, than a more stable level of feeding dairy cows over the years. Correlation analysis established a direct and reliable relationship between the delivery of first-calf heifer and the average daily increase in live weight of heifers from birth to three months at the level of 39.3 ± 1.51% (P < 0.001), from three to six months – 14.4 ± 1.63% (P < 0.001), from six months to a year – 31.4 ± 1.56% (P < 0.001) and from 12 to 18 months – 22.4 ± 1.60%, which confirms our assumptions. Undoubtedly, the increase in the intensity of growth and milk productivity of cattle cannot be caused only by the improvement of technological and economic conditions. A significant share is accounted for by the genetic improvement of the herd, in particular, the increase in conditional blood of cows introduced into the herd of the improving Holstein breed from 25.3 to 87.5%. In terms of growth intensity, heifers of the autumn birth season had an advantage, which in terms of live weight exceeded the counterparts of the spring season by 22 ± 2.4 kg or by 6.4% (P < 0.001). This resulted in a younger age at first calving (by 49 ± 5.6 days or 5.9%, P < 0.001). According to the season of the first calving, cows that calved in the summer had a slight advantage in terms of live weight at the age of one and a half years, which exceeded the analogues of the spring calving season by 22 ± 2.6 kg or by 6.3% according to P < 0.001. The animals of the winter calving season were characterized by a younger age at first calving (by 42 ± 5.9 days or by 5.0% at P < 0.001 compared to first-calf heifers of spring calving). Cows of the autumn season of the first calving were distinguished by better milk yield and higher lactation, which exceeded spring calving animals by 203 ± 57.5 kg or 3.0% (P < 0.001). Conclusions. The year of birth determines from 12.6 to 68.6% of the total phenotypic variability of the intensity of growth, reproductive ability and milk productivity of cows, the year of the first calving – from 12.5 to 70.4% with a high degree of significance (P < 0.001). The factor of the season of birth (0.1–2.3%) and calving (0.2–2.7%) has a much smaller influence on the variability of the investigated traits. The influence of seasonal environmental factors on the growth of live weight of heifers and the age of first calving turned out to be somewhat higher. The comparison of group averages confirmed the significantly smaller influence of the seasonal factor on the development and productivity of cows compared to the year of birth and first calving, established by variance analysis.
Introduction. Numerous studies of domestic scientists testify to the sometimes significant, but multidirectional influence of the year and season of calving and birth on the formation of milk productivity and other economically useful traits. In our previous studies, it was established that at the population level, among the mentioned environmental factors, the most significant influence on the phenotypic variability of the milk productivity of first-calf heifers is caused by the herd (15–22%), the year of the first calving (4.7–12%) and birth (4.2–12%), the lowest is the season of birth (0.05–0.2%) and calving (1.5–2.1%). A number of other researchers report a higher influence of the herd and the year and a smaller one of the calving season and especially the birth on the milk productivity of first-calf heifers. In our opinion, the phenotypic manifestation of signs of milk productivity in different herds is influenced by different levels of breeding and feeding, technological solutions of cow keeping and milking systems. Research materials and methods. The research was carried out on farms breeding Ukrainian Red dairy cattle of LLC "Nova Niva" of the Donetsk region. The materials of the electronic information database in the DCMS ORSEK format as of October 11, 2021 were used. In controlled animals, the intensity of growth of live weight by growing periods up to one and a half years of age, live weight at 18 months, age of first calving, length of the service period, coefficient of reproductive ability between the first and second carvings, fertility and output of milk fat and protein for the first 305 days three and higher lactation. Research results. On average, during the entire accounting period, the level of rearing of heifers up to a year ensured average daily gains in live weight at the level of almost 600 g, and at the age of 12 to 18 months – more than 550 g. Thus, the live weight of heifers and heifers at the age of one and a half practically met the standard of the Ukrainian Red dairy breed. The age of the first calving reached almost 27.9 months, which corresponded to the optimal recommendations at the time of the research (27 months). In general, the first-calf heifers under control were characterized by a relatively low reproductive ability. The duration of the service period is 72 days or 90% longer than the optimum (80 days). Univariate variance analysis established an almost equal share of the influence of the year of birth and calving factors on the studied characteristics of cows. The year of birth determines from 12.6 to 68.6% of the total phenotypic variability, the year of the first calving – from 12.5 to 70.4% with a high degree of significance. The year factor has a 1.5–2 times greater influence on live weight gains of heifers up to a year old than at the age of 12–18 months. The influence of the year of birth is 10% greater than that of the year of the first calving. The factor of the season of birth (0.1–2.3%) and calving (0.2–2.7) exerts a much smaller influence on the variability of the investigated traits. The influence of seasonal environmental factors on the growth of live weight of heifers and the age of first calving turned out to be somewhat higher. On the signs of milk productivity, seasonal fluctuations in environmental conditions show a low, but reliable influence only during the first lactation. During the second and older lactations, this effect is practically leveled off to an unreliable level of statistical significance. In most cases, intergroup differentiation was higher between years of birth than between years of first calving. In our opinion, this is caused by a higher impact on the productivity of different levels of cultivation in chronologically and naturally climatically different economic years, than a more stable level of feeding dairy cows over the years. Correlation analysis established a direct and reliable relationship between the delivery of first-calf heifer and the average daily increase in live weight of heifers from birth to three months at the level of 39.3 ± 1.51% (P < 0.001), from three to six months – 14.4 ± 1.63% (P < 0.001), from six months to a year – 31.4 ± 1.56% (P < 0.001) and from 12 to 18 months – 22.4 ± 1.60%, which confirms our assumptions. Undoubtedly, the increase in the intensity of growth and milk productivity of cattle cannot be caused only by the improvement of technological and economic conditions. A significant share is accounted for by the genetic improvement of the herd, in particular, the increase in conditional blood of cows introduced into the herd of the improving Holstein breed from 25.3 to 87.5%. In terms of growth intensity, heifers of the autumn birth season had an advantage, which in terms of live weight exceeded the counterparts of the spring season by 22 ± 2.4 kg or by 6.4% (P < 0.001). This resulted in a younger age at first calving (by 49 ± 5.6 days or 5.9%, P < 0.001). According to the season of the first calving, cows that calved in the summer had a slight advantage in terms of live weight at the age of one and a half years, which exceeded the analogues of the spring calving season by 22 ± 2.6 kg or by 6.3% according to P < 0.001. The animals of the winter calving season were characterized by a younger age at first calving (by 42 ± 5.9 days or by 5.0% at P < 0.001 compared to first-calf heifers of spring calving). Cows of the autumn season of the first calving were distinguished by better milk yield and higher lactation, which exceeded spring calving animals by 203 ± 57.5 kg or 3.0% (P < 0.001). Conclusions. The year of birth determines from 12.6 to 68.6% of the total phenotypic variability of the intensity of growth, reproductive ability and milk productivity of cows, the year of the first calving – from 12.5 to 70.4% with a high degree of significance (P < 0.001). The factor of the season of birth (0.1–2.3%) and calving (0.2–2.7%) has a much smaller influence on the variability of the investigated traits. The influence of seasonal environmental factors on the growth of live weight of heifers and the age of first calving turned out to be somewhat higher. The comparison of group averages confirmed the significantly smaller influence of the seasonal factor on the development and productivity of cows compared to the year of birth and first calving, established by variance analysis.
The results of the regression analysis of the influence of phenotypic factors on the milk productivity of cows and milk quality are presented. Reliable values of the regression coefficients of the second degree for the lactation month and lactation number indicate a non-linear relationship between these model indicators and milk yield. The value of the regression coefficient for day length indicates a positive effect of this indicator on daily hopes. The high daily air temperature had a negative impact on the milk production of cows. The negative value of the regression coefficient for the length of daylight hours is associated with a negative relationship between fat content and daily milk yield (0.225). This is also the reason for the opposite direction of the regression relationship between the fat content and the lactation month. A negative coefficient for the “daytime temperature” factor indicates that high critical air temperatures have a negative impact on both daily expectations and the fat content in milk. The negative value of the regression coefficient for the length of daylight hours is associated with a negative relationship between protein content and milk yield (0.305). This is also the reason for the opposite direction of the regression relationship of the protein content with the lactation month. A negative coefficient for daily air temperature indicates that high critical air temperatures negatively affect both daily milk yield and protein content in milk. The absence of a regression relationship between the age of the cow and the protein content in milk indicates a greater genetic dependence of this phenotypic indicator. The obtained regression coefficients indicate an increase in the somatic cells count in the milk of cows with age and month of lactation. Daylight hours and night air temperature have a negative relationship with the somatic cells count in the daily milk yield of cows. High daytime air temperature increases the somatic cells count in milk.
Technology of production and primary processing of milk in farm conditions
The introduction of new criteria for the safety of milk raw materials at the legislative level, on the one hand, made it possible to improve the supply of quality food to the population, and on the other hand, caused a decrease in the profitability of farms due to the deterioration of the marketability of milk and its price. Such a situation in the dairy business requires the search for solutions for commodity farms regarding possible ways to improve milk safety indicators as soon as possible in order to avoid a further reduction in the number of dairy cattle in Ukraine. The purpose of the research was to study the technology of obtaining and individual elements of the primary processing of milk for the number of somatic cells and the level of microbial contamination of milk raw materials. The work used general scientific methods, arbitration method, and the method of variational statistics. For this, combined samples of milk from 3 farms that used different approaches to keeping animals and technologies for obtaining milk from them, and a number of personal farms of the population were examined quarterly for one year to study the dynamics and relationships between indicators of raw material safety. A significant influence of paratypic factors on the number of somatic cells in milk was revealed, such as: milk production technology, seasonality of production, and the level of morbidity of animals for hidden forms of mastitis. At the same time, a direct correlation was established between indicators of the number of somatic cells and microbial contamination of milk at the level of 0.91 (P<0.001), which suggests that measures aimed at improving one of them will automatically improve the other. Violations of the requirements of the primary processing of milk caused a significant increase in the microbial load. Elimination of identified technological deficiencies will contribute to the increase of raw materials at milk processing enterprises
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