Anna Sawa

Effect of milk urea and protein levels on fertility indices in cows.

An analysis of the effect of milk urea and protein levels in four consecutive lactations on fertility indices of Blackand- White Polish Holstein-Friesian cows, milk recorded in the Kujawsko-Pomorskie province has been made. Poorer fertility indices were found in first-calf heifers and second lactation cows receiving energy-deficient diets and in older (third and fourth lactation) cows receiving excess dietary protein and energy. Best fertility was found in young cows fed excess protein (>3.60%) regardless of milk urea levels, and in older cows having lower and optimum levels regardless of protein levels. Cow fertility is differentiated more by milk protein levels than by urea content. Fertility parameters were poorer in first and second lactation cows than in older cows. The coefficients of correlation between milk urea and protein levels and fertility indices were very low, with the only significant differences between protein content vs. calving interval and reproductive rest period.

Relationship between Conformation Traits and Lifetime Production Efficiency of Cows

Analysis was made of the relationship between conformation traits and lifetime production efficiency of the cows that first calved in 2000 and represented the active population in the Pomorze and Kujawy regions of Poland. The CORR Pearson procedures of SAS package were used in the statistical calculations. It was found that there is a statistically significant relationship, weak or low on the Guilford scale, between conformation traits and lifetime production efficiency of the cows, which is slightly higher for milk yield than for longevity. The type and conformation traits appear to be more suitable than the detailed traits for predicting the lifetime production efficiency of cows. Lifetime performance was most strongly related to the overall score and udder score (r = 0.22), followed by the scores for type and conformation and legs and feet (r = 0.13), and detailed traits such as udder width and dairy character (r = 0.14). The highest positive effect on longevity was exerted by udder score and legs and feet (r = 0.11) and among detailed traits by udder placement (r = 0.14) and fore udder attachment (r = 0.10).

Effect of single and multiple pregnancies and calf sex on parturition process and perinatal mortality.

Abstract Material for the study was collected from the SYMLEK database and provided information on 148385 parturitions of Polish Black-and-White Holstein-Friesian cows representing the active population (part of the performance evaluation) in the Pomorze and Kujawy regions. The animals first calved in 2006 and were used or culled by the end of 2012. GLM and chi-square procedures of the SAS package were used for the statistical calculations. The number and sex of calves born had an effect (P≤0.01) on the parturition process and on the level of perinatal mortality. As the number of foetuses increased, the proportion of difficult parturitions increased from 4.3 to 28.6%. A decrease in calving ease was also related to the fact that the calf was of male sex. The risk of perinatal mortality increased after multiple pregnancy and when a bull calf was born (among single calves perinatal mortality was over 3 times as frequent in bull calves compared to heifers; among samesex twins perinatal mortality was around twice as frequent when two bull calves compared to two heifers were born; for births of opposite-sex twins, perinatal mortality was more frequent among bull calves). It was also found that perinatal mortality of calves increased with increasing level of calving difficulty. For very difficult parturitions, the risk of perinatal mortality among calves, regardless of sex, increased 10-fold in relation to unassisted parturition.

EFFECT OF DRY PERIOD LENGTH OF FIRST-CALF HEIFERS AND OLDER COWS ON THEIR PERFORMANCE IN THE NEXT PRODUCTION CYCLE

Analysis was made of the effect of dry period length in first-calf heifers and older cows from the active population of cows in the Pomerania and Kujavia regions on their performance in the next production cycle. The GLM, FREQ and CORR PEARSON procedures of the SAS package were used for statistical calculations. It was found that a dry period of 41-60 days is the most favourable in terms of next lactation milk yield. Any shortening of the dry period, especially to less than 20 days, is particularly inadvisable for first-calf heifers. Dry periods of 21-40 days are the most favourable considering survival of cows (especially the oldest cows) in the next production cycle. Extending the standard dry period of 41-60 days by 20 days causes a slight decrease in performance (as determined by the parameters mentioned above) but extending it by another 20 days is highly detrimental. Especially in the oldest cows, a dry period that is too long (over 100 days) may carry the risk of increased culling in the herd, shorter lactations and poorer reproductive performance.

Association between rump score and course of parturition in cows

Abstract. Analysis was made of the effect of rump angle and rump width, assessed using a 9-point scoring system, on the course of parturition in cows representing the active population in Pomorze and Kujawy regions of Poland. GLM and FREQ procedures of the SAS package were used in the statistical calculations. The most frequent score for rump angle was 5 (44 % of all scores) and that for rump width was 6 (30 % of all scores). Human intervention was required for 7 % of calvings, of which dystocia (surgical treatment, injury to the cow or calf, embryotomy) occurred in 0.19 % and caesarean section was performed in 0.11 % of the cases. The course of parturition was affected to a greater extent by rump angle (P

Effect of Some Factors on Number of Services per Conception in Dairy Cows

The study involved 55 685 Polish Holstein-Friesian cows whose services per conception (SPC) averaged 2.2. Statistical analysis performed using the GLM procedure of SAS, showed significant differences in SPC value within different factors. The greatest changes were associated with daily milk yield of the cows; as it increased from ≤ 20 kg to >40 kg, the number of services required to conceive increased by 0.6. SPC value deteriorated also with an increasing number of cows in the herd (by 0.37) and with an increase in milk somatic cell count, being indicative of mastitis (by 0.11). The opposite situation existed for an increase in herd production level and lengthening of the interval between calving and first insemination (decrease of SPC by 0.31). It was also found that summer was the least favourable period for insemination and winter the most favourable (SPC=2.28 vs. 2.16). Analysis of the results demonstrates that it is necessary and appropriate to account for these factors when aiming to improve cow fertility.

Dry Period Length as Related to Milk Yield and SCC During the First Month of Subsequent Lactation

Abstract Analysis was made of the effect of dry period length in primiparous and multiparous cows on daily milk yield during the first month of subsequent lactation and on milk somatic cell count (SCC) on the basis of the information about the test-day milkings of 59 138 cows. The GLM and FREQ procedures of the SAS package were used in the statistical calculations. Dry period length in the primiparous and multiparous cows had a significant effect (P≤0.01) on daily milk yield and udder health, determined based on SCC. In terms of milk yield, the most favourable dry period would be 51-70 days for both primiparous and multiparous cows. Depending on udder health, a dry period of 51-90 days can be suggested. Shorter dry periods had more undesirable effects than longer dry periods. Excessively shortened dry period (≤10 days) caused the daily milk yield to decrease by 17% in primiparous and by 13% in multiparous cows while increasing the risk of clinical changes of the cow’s udder, regardless of age. The proportion of milk samples that showed evidence of clinical mastitis also increased when the dry period was excessively long (>90 days), especially in multiparous cows.

ANALYSIS OF MILK AND REPRODUCTIVE PERFORMANCE OF THE ACTIVE POPULATION OF COWS IN POLAND

Changes in the genotypic structure of cows, yield of milk, fat and protein, fat and protein content of milk, relationships between milk components, i.e. the protein to fat ratio (PFR) and the difference between fat and protein content (DFP) were examined using data from the Polish Federation of Cattle Breeders and Dairy Farmers for 2001–2009. In addition, analysis was made of changes in the length of calving interval and age at first calving. Average yield of milk and its components was found to increase in all milk recorded cows. Changes in the relationship between basic milk components differed between the breeds. A decrease in fat content was found in the milk from Polish Black-and-White Holstein-Friesian, Jersey, Montbeliarde and Polish Red-and-White cows, and an increase in protein content was recorded in the milk from Polish Black-and-White Holstein-Friesian, Polish Red-and-White, Simmental and Montbeliarde cows. These changes had a favourable effect on the PFR ratio in Polish Holstein-Friesian cows, especially those of the Black-and-White variety. Calving interval and age at first calving were found to increase in all the cows except the Montbeliarde breed.

Influence of Perinatal Diseases on Cow Milk and Breeding Usefulness

Investigations have shown that perinatal diseases of the prepartum period leads to greater milk productivity in comparison to healthy animals, obtained from cows possessing follicular cysts on ovaries, with uterus inflammation and mastitis. The lowest daily productivity was observed for cows in which ketose was diagnosed, whereas cows with mastitis showed the highest productivity. Occurence of the disorders was correlated with elongation of OMC by 9-109 days in relation to the healthy cows. The occurrence of follicular cysts and inactivity of the ovaries had most adverse influence on the length of OMC, i.e. extending it by 230 and 228 days, respectively. Reproductive indices decreased in all cases of prepartum disorders, however, the differences were not confirmed statistically.

Effect of Postpartum Endocrine Function, Metabolism, and Mastitis on Fertility in High-Yielding Cows – A Review

Abstract Decreasing fertility in dairy cows, especially in the highest yielders, may be due to excessive metabolic burdens placed on their bodies. Many authors attribute decreasing reproductive efficiency in high-yielding cows to energy deficiencies in early lactation and to associated metabolic and hormonal disorders. The complexity of the issues involved in the efficient reproductive management of cows and the scientifically and practically important understanding of factors affecting fertility in high-producing cows mandate continuous updating of existing knowledge. The aim of this study was to present the effect of postpartum endocrine function, metabolism, and mastitis on fertility in high-yielding cows. Gaining insight into these mechanisms and their relationships with factors such as nutrition and milk yield appears to be crucial for improving dairy cow fertility.