Matti Ojala

Effects of Composite β- and κ-Casein Genotypes on Milk Coagulation, Quality, and Yield Traits in Italian Holstein Cows

The aim of the study was to estimate the effect of the composite CSN2 and CSN3 genotypes on milk coagulation, quality, and yield traits in Italian Holstein cows. A total of 1,042 multiparous Holstein cows reared on 34 commercial dairy herds were sampled once, concurrently with monthly herd milk recording. The data included the following traits: milk coagulation time; curd firmness; pH and titratable acidity; fat, protein, and casein contents; somatic cell score; and daily milk, fat, and protein yields. A single-trait animal model was assumed with fixed effects of herd, days in milk, parity, composite casein genotype of CSN2 and CSN3 (CSN2-CSN3), and random additive genetic effect of an animal. The composite genotype of CSN2-CSN3 showed a strong effect on both milk coagulation traits and milk and protein yields, but not on fat and protein contents and other milk quality traits. For coagulation time, the best CSN2-CSN3 genotypes were those with at least one B allele in both the CSN2 and CSN3 loci. The CSN3 locus was associated more strongly with milk coagulation traits, whereas the CSN2 locus was associated more with milk and protein yields. However, because of the tight linkage between the 2 loci, the composite genotypes, or haplotypes, are more appropriate than the single-locus genotypes if they were considered for use in selection.

Repeatability estimates for milk coagulation traits and non-coagulation of milk in Finnish Ayrshire cows

Effects of systematic environmental factors and milk production and quality traits on milk coagulation properties (MCP), and on repeatability of those traits were estimated from 979 milk samples collected once a month over a period of 2 years from 83 Finnish Ayrshire cows. Estimation was based on a multitrait animal model and REML methodology. In addition, persistence of non-coagulation of milk in individual cows, and factors associated with it were established from a sub sample of 24 cows producing non-coagulating (NC) milk at least once. MCP were at their best during the first lactation, at the beginning and at the end of lactation, and during grazing seasons. Variation in MCP with systematic environmental factors was partly due to variation in composition and quality of milk, especially in pH and ln (somatic cell count, SCC). Coefficients of repeatability for milk coagulation time and curd firmness were 0.65 and 0.68. These estimates were of the same magnitude as those for protein content, but were higher than those for daily milk yield, fat content, pH, and SCC. Based on the repeatability estimates for the milk coagulation traits and effects of the environmental factors, cows should be sampled at least three times during a lactation to estimate reliably breeding values for the milk coagulation traits. A total of 10% of the milk samples did not coagulate in 30 min after addition of rennet. Cows that produced NC milk at least once (30% of the cows) could be classified into those that produced NC milk only a few times during a lactation and those that produced NC milk at almost every sampling. Based on logistic regression analyses, peak and mid-lactation, high milk yield, low protein and fat content and high pH increased the risk of non-coagulation of milk.

Chromosomal Regions Underlying Noncoagulation of Milk in Finnish Ayrshire Cows

About 10% of Finnish Ayrshire cows produce noncoagulating milk, i.e., milk that does not form a curd in a standard 30-min testing time and is thus a poor raw material for cheese dairies. This phenomenon is associated with peak and midlactation, but some cows produce noncoagulating milk persistently. A genomewide scan under a selective DNA pooling method was carried out to locate genomic regions associated with the noncoagulation of milk. On the basis of the hypothesis of the same historical mutation, we pooled the data across sires. Before testing pools for homogeneity, allele intensities were corrected for PCR artifacts, i.e., shadow bands and differential amplification. Results indicating association were verified using daughter design and selective genotyping within families. Data consisted of 18 sire families with 477 genotyped daughters in total, i.e., 12% of each tail of the milk coagulation ability. Data were analyzed using interval mapping under maximum-likelihood and nonparametric methods. BMS1126 on chromosome 2 and BMS1355 on chromosome 18 were associated with noncoagulation of milk across families on an experimentwise 0.1% significance level. By scanning gene databases, we found two potential candidate genes: LOC538897, a nonspecific serine/threonine kinase on chromosome 2, and SIAT4B, a sialyltransferase catalyzing the last step of glycosylation of κ-casein on chromosome 18. Further studies to determine the role of the candidates in the noncoagulation of milk are clearly needed.

Factors Affecting Body Weight and Its Association with Milk Production Traits in Finnish Ayrshire and Friesian Cows

Abstract Data from the Finnish milk recording system consisting of records for the first three parities from a total of 66 554 Ayrshire and 9664 Friesian cows were analysed using REML methodology and sire model. Factors with statistically significant effects on body weight were: year, age and season of calving and lactation stage. The influence of the random herd effect was also evident. Within-herd herit-abilities for body weight in the first three parities were from 0.29 to 0.41 in Ayrshires and from 0.21 to 0.34 in Friesians. Genetic correlations between body weight and 305-day milk, fat and protein yields varied from +0.09 to +0.34 in the Ayrshire data and from -0.06 to +0.28 in the Friesian. Phenotypic correlations were slightly larger and positive in both breeds. Genetic correlations between body weight and fat and protein percentages were negative and phenotypic correlations were near zero.

Measures of before and after breeding daily gains of dairy replacement heifers and their relationship with first lactation milk production traits

Abstract A field study was conducted to study the relationships between average daily gain (ADG) of heifers and their first lactation milk yield. To predict the body weight (BW) the heart girth of 4058 heifers was measured by AI-technicians. Based on these measurements and national milk recording data, the ADGs before and after breeding were calculated. Other variables collected were after calving BW, calving age, and milk production yields on first lactation. After edits the final data included 2194 Ayrshire (Ay) and 738 Friesian (Fr) heifers and their 7215 relatives. Data used for calving BW and ADGs after breeding was 43% smaller because of missing information. The average BW and age at breeding were 356 kg and 483 days for Ay and 376 kg and 484 days for Fr, respectively. The after calving BW for Ay was 502 kg and for Fr 520 kg. The weights correspond to ADGs of 660 g (S.D. 99 g) and 695 g (S.D. 114 g) before breeding, and 497 g (S.D. 190 g) and 492 g (S.D. 196 g) after breeding for Ay and Fr breeds, respectively. The average 305-day milk yield for Ay was 6198 kg and for Fr 6440 kg. Positive genetic correlations between growth rate before (0.13±0.11) and after (0.34±0.17) breeding and milk yield as well as calving BW and milk yield (0.26±0.13) were found. The environmental correlation between ADG before breeding and milk yield was positive (0.13±0.04), while the ADG after breeding and milk yield was uncorrelated (−0.01±0.04). Based on the feeding trials a negative environmental correlation between ADG before breeding and milk yield could have been expected. It was concluded that the negative effect could not be estimated, because of the disturbance caused by herd effect. Also, the fact that most of the heifers had been reared within recommended limits of ADG could have affected the results.

Estimates of Genetic and Phenotypic Parameters for Racing Performance in Young Trotters

Abstract The data consisted of race records of 3 through 5-year-old Finnish Standardbred trotters (n=2637) and of 4 through 6-year-old Finnhorse trotters (n=2207). Heritability estimates for the traits studied were distinctly larger in Standardbred trotters than in Finnhorses. The largest heritability estimates of the traits in both breeds and in different age classes were observed for best time (0.09–0.52), and the lowest for number of starts (0.02–0.13) and for age at first start and age at best time (0.06–0.13). Repeatabilities of the traits were moderately large ranging between 0.24 and 0.68. Largest repeatabilities were observed for best time on volt-start. In general, young age at first start was associated with superior performance. The performance of one season at young age was highly correlated with the performance of the career over the first three years.

Estimates of genetic parameters for carcass traits in Finnish Ayrshire and Holstein-Friesian

Abstract The aim of this study was to estimate genetic parameters for slaughter weight, and carcass fleshiness and fatness in Finnish Ayrshire and Holstein-Friesian bulls and heifers. Animal model, sire model and sire maternal grandsire model were tested for their suitability to evaluate young sires in progeny test. There were 38 188 records on animals slaughtered in two slaughter houses during a period of 20 months. Effects of year-month of slaughter, age at slaughter, sex and breed were statistically significant, and herd accounted for about 20–57% of the total variation in the data. Estimates of heritability in the different breed by sex data sets were in range of 0.07–0.14 for slaughter weight, 0.16–0.31 for fleshiness and 0.08–0.16 for fatness, whereas the corresponding within herd heritabilities varied from 0.15 to 0.29, 0.29 to 0.39 and 0.12 to 0.29, respectively. There was a positive genetic correlation of 0.38–0.66 between slaughter weight and fleshiness, whereas fatness was not genetically correlated with the other studied traits. All within herd correlations were high, from 0.55 to 0.93, and phenotypic and environmental correlations were also high or moderate. In the estimation of (co)variance components, sire model and sire maternal grandsire model were preferred to animal model due to computational requirements, and sire maternal grandsire model to sire model due to the possibility of including the sire path of maternal pedigree.

Influence of Birth-month on Age at First Start and Racing Performance in Young Trotters

Abstract Race records for 2 through 5-year-old Finnish Standardbred trotters (n=3140) and for 3 through 6-year-old Finnhorse trotters (n=2634) were used to estimate the influence of birth-month on age at first start and racing performance. Standardbred trotters born from January to March were about half a year younger at first start than their contemporaries born from August to October. The effect of birth-month on racing performance of horses was more pronounced in Standardbred trotters than in Finnhorse trotters. The influence of birth-month was expressed most clearly in three-year-old Standardbred trotters; horses born from January to March were faster (p<0.001), had greater earnings (p<0.01) and a larger number of both first placings (p<0.05) and first-to-third placings (p<0.001) than their racemates born later. In regard to the performance over the whole career in Standardbred trotters, the most advantageous months of birth were from January to May. In Finnhorses the most advantageous birth-months se...

Experience from application of animal breeding theory in Nordic horse breeding

Abstract The current status of the application of animal breeding theory in the horse breeding schemes of the five Nordic countries is reviewed. Figures showing the breeding population size of the main breeds are given and the horse breeding organizations of each country were introduced. The genetic research work on horses, with the main emphasis on quantitative genetics, is reviewed, and practical application of genetic research results and methodology is presented. Advanced application of the animal breeding theory is found in the breeding of trotters, warmblood riding horses and Icelandic toelters. The need for reorganization of the breeding plans in many other horse breeds is emphasized.

Effects of Year, Sex, Age and Breed on Annually Summarized Race Records for Trotters in Finland

Abstract Annually summarized race records from the nine years 1977 through 1985 were available on 3421, 5062 and 4870 three-, four- and five-year-old Standardbred trotters and 3606, 4078 and 3886 four-, five- and six-year-old Finnish trotters. The objectives of the study were to determine the statistical significance and to quantify the magnitude for the effects of year, sex, and year×sex interaction on these five traits: square root of percentage of first placings in a year, percentage of first to third placings in a year, fourth root of annual earnings per start, a horses best annual racing time on volt-start and a horses best annual racing time on autostart. Year×sex interaction did not have a statistically significant effect on any of the traits. Statistical significance of the effects of year and sex on the traits studied was not consistent in the three age groups in the two breeds. Males were superior to females in all traits. Judged by a horses best annual racing time on volt-start, males were 1...