Mariusz Bogucki

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.

Effect of temperament on performance of primiparous dairy cows

Abstract This study was designed to analyse the effect of milking behaviour (temperament) of primiparous dairy cows on their milk and reproductive performance as well as survival to the second lactation. Milk performance, reproductive performance and culling data on 12028 Polish Holstein-Friesian primiparous dairy cows were acquired from the SYMLEK database. Using the methodology of the Polish Federation of Cattle Breeders and Dairy Farmers, the temperament of the cows was assessed as: 1 - calm, 2 - normal, 3 - excitable or aggressive. Primiparous cows from the analysed population were characterized by averagely normal temperament and optimal milking speed. Daily and lactation yield depended (P≤0.01) on the temperament of cows. Excitable (aggressive) cows had higher daily and lactation yield compared to normal and calm cows. The temperament trait was found to correlate (P≤0.01) also with functional traits such as milking speed, survival to the second lactation, and culling level. As milking speed increased, the proportion of cows with calm temperament decreased and that of excitable (aggressive) primiparous cows increased. As the temperament score increased, so did the proportion of primiparous cows sold for further breeding. Excitable (aggressive) primiparous cows had the lowest chance of survival to the second calving.

Longevity of Cows Depending on their First Lactation Yield and Herd Production Level

Abstract The effect of first lactation yield and herd production level on longevity was studied using data from the SYMLEK database on 12045 Polish Holstein-Friesian cows in 1371 farms from the active population in Pomerania and Kujawy. The cows first calved in 2008 and were used or disposed from the herds by the end of 2015. FREQ, GLM and CORR procedures from the SAS package were used in the statistical calculations. The optimum level of first lactation milk from the viewpoint of longevity varies according to herd production level, which serves as a measure of the quality of rearing conditions. If the living conditions are not adapted to the high milk production of first calvers, there is a possibility that their productive life will be shortened and number of calvings decreased. The percentage of voluntary culling decisions by the breeder, which included the sale for further breeding, low milk yield and old age, averaged 9% and decreased with increasing herd production level from 16% to around 6%. The main reason for culling was infertility (around 40% on average). Culling due to infertility was particularly common among the cows which produced more than 11000 kg milk as first calvers.