Wojciech Neja

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.

Milk protein polymorphisms and effect of herds on cows` milk composition

Kappa-casein (CSN3) and beta-lactoglobulin (LGB) loci affect milk yield traits and the quality of milk protein. Their polymorphisms explain the role of genetic variance and facilitate estimation of breeding value. Our research was aimed at estimating the effect of beta-lactoglobulin and kappa-casein genotypes on milk yield and the chemical composition of milk, for cows bred in three herds in the kujawsko-pomorskie province. We divided the cows into three groups depending on their beta- lactoglobulin and kappa-casein polymorphisms: AA, AB and BB. The percentage of AB LGB heterozygotes in the examined population was the highest, at 44%; whereas the frequency of both gene alleles was at a similar level. In the kappa-casein gene, we found that there was a predominance of AA CSN3 genes (0.69), and a small percentage of BB CSN3 genotypes (0.07). We also observed a higher frequency of the A allele (0.81) as compared to the B allele (0.19), which is desired in breeding. Analysing the influence of the examined factors, we established a statistically significant influence of the barn as well as interactions between the barn and the LGB and CSN3 genotype on the percentage of fat and protein in milk from all examined lactations. Milk yield is influenced by the interaction between examined genotypes and the LGB genotype. The highest fat and protein content in the first lactation was found in animals with the AB LGB genotype: 4.53% of fat and 3.41% of protein. In lactations 2 and 3, the highest values for these parameters were noted for cows with the AA LGB genotype. As to the kappa-casein gene, we observed that cows with the AA CSN3 genotype constituted the largest group. Heterozygous animals produced the highest amount of milk with higher fat and protein yield as compared to the other groups.

Estimation of bodyweight from body measurements and determination of body measurements on Limousin cattle using digital image analysis

The objective of this study was to predict bodyweight and estimate body measurements of Limousin cattle using digital image analysis (DIA). Body measurements including body length, wither height, chest depth, and hip height of cattle were determined both manually (by measurements stick) and by using DIA. Body area was determined by using DIA. The images of Limousin cattle were taken while cattle were standing in a squeeze chute by a digital camera and analysed by image analysis software to obtain body measurements of each animal. While comparing the actual and predicted body measurements, the accuracy was determined as 98% for wither height, 97% for hip height, 94% for chest depth and 90.6% for body length. Regression analysis between body area and bodyweight yielded an equation with R2 of 61.5%. The regression equation, which included all body traits, resulted in an R2 value of 88.7%. The results indicated that DIA can be used for accurate prediction of body measurements and bodyweight of Limousin cattle.

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.

Behaviour of calves in the first weeks of life

Behavioural observations were conducted on 20 calves (10 bull calves and 10 heifer calves). The first series of observations was made in the first 4 days of life, and the second after a month (within 30 to 33 days of calving). Time from birth to first unassisted standing (standing on all extended legs) ranged from 16 minutes (heifers) to 158 minutes (bulls) for normal calving. Calves born from normal parturitions stood up after an average of 81 minutes and those born from difficult parturitions after 302 minutes. Calves that required assistance at calving showed shorter standing and longer lying time. In the first 4 days of life and after a month, both male and female calves were more often in left lateral recumbency when resting. Heifer calves more often visited the feeder while bull calves more often consumed concentrates, water and hay.

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

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.