Milk samples from three Jersey and three Holstein herds were used to determine if the degree of churning correlated with the initial milkfat assay, and also to determine if the churned milkfat could be measured as accurately as the initial milkfat using the Milko-Tester. Regression lines for the initial milkfat test versus churned milk- fat test fit polynomial curves. The degree of churning was greater for Jerseys than Holsteins and correlated with the initial milkfat test. The repeatability of initial milkfat tests vas 0.98 for Jerseys and 0.99 for Holsteins. However, the repeatability of churned milkfat tests was lower for both breeds, especially for Jerseys. This indicated that the churned sample could not be measured for its milkfat content as accurately as the nonchurned sample. Churned milkfat samples all tested lower than initial milkfat samples, thus the Milko-Tester Mark III was unable to provide an initial fat test estimate following sample churning. Cows were different from each other in the difference between initia1 and churned milk fat tests. This suggested that cows which produce milk with a higher tendency for churning are apt to receive less reliable milkfat tests from central laboratories than other cows, when all milk samples are subjected to churning conditions.

No description available.

No description available.

This study was conducted to determine the relationships among the linear type traits of rump angle, rump width, rump length, rear legs side view, rear legs position, rear legs rear view, tailhead, vulva angle, mobility, pasterns, foot angle, and toes with reproductive performance (days open and times bred) in Holstein cows and to develop indices to predict reproductive performance from mathematical functions of the anatomical traits. Two trials were conducted. The first trial involved 7630 registered Holstein cows from Oregon and California. The regression analysis (R²) showed only 1.1% of the variability of times bred and 1.3% of the variability of days open was accounted for by the rump and rear leg type traits. In the second trial, 8155 Holstein cows, both registered and grade, were analyzed using the linear type traits of rump angle, rump width, rear legs side view, rear legs position, rear legs rear view and foot angle.. Grade and registered cows were analyzed separately to determine if differences in management between them would be reflected in the statistical analysis. Evaluator, lactation number (parity), season, geographic location, and the interaction of evaluator and lactation number had a significant effect on most of the type traits and the scorecard category (General Appearance, Mammary System, Dairy Character and Body Capacity) scores examined. The effects of these variables were statistically removed and the residuals of the type traits were used in the final regression analysis. Using stepwise regression analysis, several non-significant traits were omitted from the final model. The analysis used days open and times bred as dependent variables. Lactation number, mature equivalent milk, foot angle, rump width and their respective quadratics were independent variables, as were season calved and geographic location. The regression analysis (R²) indicated that 5.3% of the variability in days open and 4.7% of the variability in times bred in registered cows was accounted for by the type traits, foot angle and rump width, respectively, when the effects of season calved, geographic location, lactation number and mature equivalent milk were included in the model. For the grade cows the regression analysis (R²) indicated that 3.5% of the variability in days open was accounted for by foot angle. None of the type traits examined had a significant effect on times bred. This study detected no significant influence of rump angle or rear leg position, as described by the HFA linear classification program, on reproductive performance. However, our analysis indicated that fertility decreased as rear foot angles became more steep in grade and registered cows and as rump width increased in registered cows. / Graduation date: 1991

En el estudio se utilizaron 100 bovinos machos, 50 de la raza Holstein (Bos taurus) y 50 de la raza Nelore (Bos indicus), con edades que fluctuaban entre 12 a 24 meses. El objetivo fue determinar la curvas de variación Post mortal del pH para ambas razas durante las primeras 24 horas, las medidas del pH fueron tomados en el músculo Longissimus dorsi, y los datos fueron sometidos a análisis de regresión. El valor del pH se expresó a través de ecuaciones de regresión, por medio del coeficiente de correlación (R2) que fue de tipo cúbica, obteniéndose para la raza holstein (R2 = 0.814) y Nelore (R2 = 0.767). Las medidas del pH se realizaron después de la sangría, en los horarios de 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 18, 24 horas Post mortem. Encontrando los valores estimados de pH para las 24 primeras horas Post mortem para la raza Holstein (Bos taurus) de 6.81, 6.55, 6.33, 6.14, 5.97, 5.84, 5.73, 5.64, 5.58, 5.53, 5.50, 5.48, 5.48, 5.48, 5.49, 5.51, 5.53, 5.55, 5.57, 5.59, 5.60, 5.60, 5.59, 5.57, y para la raza Nelore (Bos indicus) de 6.71, 6.46, 6.24, 6.05, 5.89, 5.75, 5.65, 5.56, 5.50, 5.45, 5.42, 5.40, 5.39, 5.39, 5.40, 5.41, 5.43, 5.44, 5.45, 5.46, 5.46, 5.45, 5.43, 5.40, respectivamente. Los valores de pH en la carne muestran una rápida caída durante las 12 primeras horas y los valores de pH de la raza Holstein (Bos taurus), con respecto a la raza Nelore (Bos indicus) son ligeramente mayores (p < 0.05), aunque siguen similar tendencia a lo largo de las 24 primeras horas Post mortem. / In this study was used 100 cattle male cows, being 50 of Holstein breed (Bos taurus) and 50 Nelore breed (Bos indicus), with ages was between 12 a 24 moths. The objetive of this study was to determine the pH Post mortal variation curves for both breeds during the first 24 hours, the pH measurements was took in the Longissimus dorsi muscle, and the data was to submited regression analysis. The pH value was expressed through the regression ecuations, related to the correlation coefficient (R2) that was a cubic one, the result were (R2 = 0.814) for Holstein and (R2 = 0.767) for Nelore. The pH measurements were perfomed after the slaughter, in the periods of 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 18, 24 hours Post mortem. Find the values to admited of pH for first 24 Post mortem hours the results were for Holstein breed (Bos taurus) of 6.81, 6.55, 6.33, 6.14, 5.97, 5.84, 5.73, 5.64, 5.58, 5.53, 5.50, 5.48, 5.48, 5.48, 5.49, 5.51, 5.53, 5.55, 5.57, 5.59, 5.60, 5.60, 5.59, 5.57, and for Nelore breed (Bos indicus) of 6.71, 6.46, 6.24, 6.05, 5.89, 5.75, 5.65, 5.56, 5.50, 5.45, 5.42, 5.40, 5.39, 5.39, 5.40, 5.41, 5.43, 5.44, 5.45, 5.46, 5.46, 5.45, 5.43, 5.40, respectively. The meat pH values show a fast fall during the first 12 hours and the Holstein (Bos taurus) pH values in contrast to Nelore (Bos indicus) are slightly higher (p < 0.05), even thoughn they follow a similar tendency during the first 24 hours Post mortem.

Texte remanié de: Diss.--Philosophische Fakultät I--Berlin--Humboldt-Universität, 1999. / Bibliogr. p. 229-256.

Thesis (doctoral)--Christian-Albrechts-Universität zu Kiel, 2001.

Thesis--Lund. / Summary in German. Includes bibliographical references (p. 226-234).

In order to establish a method of assessing the degree of inbreeding within herds of cattle, we constructed a calibration index relating kinship and the degree of DNA band sharing in DNA fingerprints. Firstly, chickens were used as a model system to test the possibility of using microsatellite DNA as a probe for DNA fingerprinting in inbreeding analysis. Six genetic groups of chickens with estimated coefficients of inbreeding ranging from 0.026 to $>$ 0.98 (pedigree analysis) were fingerprinted using the minisatellite probe derived from M13 and the microsatellite probe (CAC)$ sb5$. The degree of band sharing using either probe increased in concert with the known amount of inbreeding and was described by the equation Y = 0.56X ($ pm$0.06) + 0.42 ($ pm$0.03); r = 0.998. Since in-gel hybridization using the microsatellite probes was faster and less labour intensive than using the minisatellite probe, it was used in the subsequent studies. Pedigree analysis in Holstein dairy cattle allowed for the empirical calibration of the association of band sharing with the coefficient of relatedness, (r), defined as the expected proportion of genes in 2 individuals that are identical by descent (i.e. for monozygous twins r = 1; for first order relatives r = 0.5; for half sibs r = 0.25 etc.). The average band sharing between pairs (6 pairs at each r value) of individuals within each class formed the basis for calibration. DNA was digested using RsaI. The relationship between band sharing and relatedness was well represented by a linear approximation Y = 0.51X ($ pm$0.09) + 0.50 ($ pm$0.04); r = 0.992. Using this calibration curve, random samples of animals within herds can be tested to establish the herd variability and to minimize inbreeding.

The effect of composite and descriptive linear type traits on Functional Herd Life in Holstein cows was studied by means of Survival Analysis (Ducrocq and Solkner, 1998a). The original data set contained 331,105 lifetime records from the Programme d'Analyse des Troupeaux Laitiers du Quebec, from January 1980 to March 1995. Only 191,167 records (or cows) had type information. Mixed Weibull models were fitted to analyse the data; the probability of being culled (hazard) was defined as a product of a baseline Weibull hazard function and explanatory variables. The heritability estimates for Functional Herd Life were 0.07 in the log scale and 0.15 in the original scale. Sire Estimated Transmitting Ability for FHL, expressed as relative culling rate, ranged from 0.6 to 1.4 for all models. Solutions for fixed effects (all significant) indicated a higher probability of being culled for primiparous cows calving at older ages, for cows producing below herd average, for first lactation cows in the first and last stage of lactation and for older cows at the end of lactation. The risk of being culled did not change for cows in herds decreasing or increasing in size. Cows classified with a high score for Final Score were less likely to be culled; Final Score seems to be an important selection criteria among Quebec producers. Feet and Legs, Rump and Mammary System are traits that producers consider in their culling policies; cows classified with a high score had more chance of surviving. Among the linear type traits, the 5 traits with the highest impact on productive life, were Rear Attachment Height, Fore Attachment, Bone Quality, Stature and Fore Teat Placement; Quebec producers seem to consider these traits when they make their culling decisions.