Genealogical data of Boer and Nubian goats in Mexico.

The pedigree file of the Boer and Nubian goat breeds in Mexico was constructed using the national database provided by the Asociación Mexicana de Criadores de Ganado Caprino de Registro. Field technicians routinely updated the goat national database by recording information from flocks participating in the performance-recording system. Information on animal identification number, parents, birth date, sex, breed, and farm of origin were used to undertake pedigree analyses using the ENDOG program (version 4.8). This paper presents a pedigree data file, tables and figures of characteristics of pedigree data, pedigree analyses, pedigree integrity, effective population size and genetic conservation index. The data can be used to estimate other population parameters, to monitor the genetic diversity of the Boer and Nubian goat breeds in Mexico, and also to design balanced breeding programs, maintaining genetic variation at reasonable levels and maximizing genetic progress in these populations.

Dataset on growth curves of Boer goats fitted by ten non-linear functions.

Data on the description of growth of female Boer goats from the Mexican national breeding flock are presented. Goat meat is highly appreciated for the preparation of traditional dishes of Mexican cuisine, and its demand is on the rise. Boer goats are of relatively recent arrival in Mexico and the size of the performance-recorded flock has been increasing steadily in the last ten years. Repeated measures of body weight at different ages from birth to adulthood of Boer goats are scarce. When available, such data can be used to describe the growth pattern and the meat production potential of goat meat breeds such as the Boer. This paper presents data on estimators of growth curve parameters, plots of average predicted growth curves, plots of residuals on age, and data on goodness of fit statistics of ten non-linear functions fitted to describe the growth curve of Boer goats.

Genotype by feeding system interaction in the genetic evaluation of Jersey cattle for milk yield.

Results of studies in dairy cattle about the magnitude of the genotype-environment interaction (GEI) are variable, depending on the definitions of genotype and environment. Therefore, the objective of this study was to determine the magnitude of the interaction of genotype and feeding system (confinement and grazing) in the Mexican genetic evaluation of Jersey cattle for milk yield. The number of lactations and animals in the pedigree used were 5122 and 18 432. An animal model and the MTDFREML program were used to estimate genetic parameters and predict genetic values of the animals. Bivariate analysis was carried out considering the performance of confined and grazing cows as two different traits. Three indicator variables were used to assess GEI: (i) magnitude of the genetic correlation coefficients, (ii) correlation between predicted breeding values and (iii) frequency of coincidence in the ranking of top sires. The magnitude of GEI depended on the choice of the indicator variable. The estimate of genetic correlation coefficient less than unity (0.76; P < 0.05) suggested the presence of biologically important GEI. The differences in phenotypic averages and variances between confinement and grazing systems seem to be the main causes for the genotype by environment interaction detected. However, the correlation coefficient between breeding values from confined and grazing animals (0.96) and the frequency of coincidence between breeding values of common sires within the top 100 in confinement and grazing (0.86) indicated low-to-moderate re-ranking of animals or top sires. In addition, the high correlations between predicted breeding values of Mexican genetic evaluation and the two environments (0.99 and 0.93 for confinement and grazing) indicated that for the two feeding systems, breeding values from national analyses could be safely used.

Prediction of genetic values of sires for growth traits of crossbred cattle using a multivariate animal model with heterogeneous variances.

The purpose of this study was to evaluate the effect of adjusting for heterogeneous variances across breed groups on prediction of breeding values (PBV) of selected sires and on breed of sire effects. Data on weights at birth (BWT), 200 d (WW), and 365 d (YW) of purebred and crossbred calves from matings of Angus (A), Hereford (H), Polled Hereford, Charolais, Shorthorn, Simmental, Limousin, Maine-Anjou, Chianina, Gelbvieh, Tarentaise, and Salers Bulls to A and H cows were used. Calf performance in H and A dams was treated as a different trait. Models compared included fixed birth year, cow age, and sex classes and crossbreeding effect as a covariate; random direct and maternal genetic and permanent environmental effects were also included, but their variance structure was different. Model I assumed homogeneous variances across breed groups. Model II accounted for heterogeneous variances. Sires were ranked based on PBV from each model, and means of PBV of selected sires were calculated based on Model II. Differences between mean PBV were small for BWT, intermediate for WW, and larger for YW. Differences in PBV of selected sires increased as selection intensity increased, but only for WW and YW. Large differences in mean PBV of selected sires between maternal environments (H vs A) were observed for WW and YW for various sire breeds. Means of PBV of selected sires based on Model II exceeded those based on Model I by 6 to 16 kg of YW for various selection intensities and maternal environments. Estimates of breed of sire effects from Model I or II were similar for BWT and WW, but large differences were found for YW. Results indicate that some additional economic returns may be gained by commercial producers if sires are chosen across breeds based on predicted genetic values computed with models accounting for heterogeneous variances.

Correlations for genetic expression for growth of calves of Hereford and Angus dams using a multivariate animal model.

The purpose of this study was to estimate the correlation between the expression of genes from sires in purebred and crossbred progeny (rPC) and in Hereford and Angus F1 calves (rHA). Performance traits were weights at birth, 200 d, and 365 d. Progeny from Hereford, Polled Hereford, and Angus bulls mated to Hereford or Angus cows were used to estimate rPC. Progeny from Charolais, Shorthorn, Simmental, Limousin, Maine-Anjou, Chianina, Gelbvieh, Tarentaise, and Salers bulls mated to Hereford or Angus cows were used to estimate rHA. Performances in purebreds (P) and crosses (C) or in Hereford (H) and Angus (A) F1 calves were treated as separate traits. A multivariate animal model with birth year-cow age-sex subclasses, random correlated direct and maternal additive genetic effects, and maternal permanent environmental effects was used. Separate analyses were done by breed of sire. A derivative-free algorithm was used to obtain REML estimates of (co)variance components. Weighted averages across breeds of estimates of heritability for P, C, H, and A were, respectively, .61, .51, .47, and .40 for birth weight, .41, .46, .37, and .34 for weaning weight, and .50, .49, .42, and .46 for yearling weight. Estimates of rPC ranged from .88 to .97, .55 to .94, and .68 to .86 for weights at birth, 200 d, and 365 d, respectively. Estimates of rHA ranged from .43 to .99, .56 to .95, and .50 to .98 for weights at birth, 200 d, and 365 d, respectively. Weighted averages of estimates of rPC and rHA across sire breeds were, respectively, .93 and .85 for birth weight, .77 and .73 for weaning weight, and .76 and .86 for yearling weight. These results indicate that ranking of sires producing purebreds or crosses, or crossbred calves from different breeds of dams, is approximately the same for birth and yearling weights, but some reranking might occur for weaning weight.

Breed comparisons for growth traits adjusted for within-breed genetic trend using expected progeny differences.

Records (2,910) of birth (BWT), weaning (WW), and yearling weight (YW) of F1 calves produced in a top-cross experiment involving Angus, Hereford, Pooled Hereford, Charolais, Limousin, Simmental, Gelbvieh, Maine-Anjou, Chianina, Tarentaise, Shorthorn, and Salers bulls mated to Hereford and Angus cows and records (4,592) of WW on three-breed-cross calves out of 986 F1 females of the same breed crosses were used in this study. The purposes were to estimate how much of the EPD of the sires was realized in crossbred calves and to estimate sire breed effects for the traits adjusted for genetic trend and sire sampling. Published EPD for BWT, WW, YW, net maternal ability (MLK), and maternal WW (MAT) were used. Average regressions (kilograms/kilogram +/- SE) of BWT, WW, and YW of F1 calves on EPD of the sire were 1.04 +/- .10, .88 +/- .11, and 1.40 +/- .11, respectively. The regressions (b, kilograms/kilogram) were similar to the expected values of 1.0 except for YW. For WW of three-way-cross calves on MLK EPD of the maternal grandsire, b was 1.02 +/- .11, which was not different from the expected value of 1.0. Estimated sire-breed means were adjusted to a 1982 genetic base by adding b times the difference of the 1982-breed-mean EPD and mean EPD of sires used in the study. Three different adjustments were compared using the b pooled across breeds, a separate b for each breed, and the expected b of 1.0. In general, the adjustments tended to regress breed of sire means toward the average of all breeds, particularly for BWT and WW of F1 calves, and for WW of three-breed crosses. The effect of type of adjustment varied among breeds, but in most cases small differences resulted from using average or expected b. For WW, the range for net maternal effects among breeds was larger than that for direct breed effects.

Economic evaluation of heterosis and culling policies for lifetime productivity in Hereford, Angus, shorthorn, and crossbred cows.

Experimental lifetime performance data obtained from 156 straightbred Hereford, Angus, and Shorthorn and 172 first-cross heifers were used to estimate heterosis for economic efficiency in a 100-cow herd at age equilibrium under three culling policies and at terminal ages from 6 to 12 yr. All nonpregnant heifers and cows greater than 9 yr of age were culled. The culling policy for removal of nonpregnant cows from second parity through 9 yr of age were 1) no culling, 2) after two consecutive years (actual), and 3) all (imposed). Efficiency was calculated as input cost per unit of output value. A 10-yr average was used for costs of replacement heifers, cow units, and the ratio of calf:cull cow prices (PR), plus higher and lower PR. Input included costs for both cow units and purchased replacements. Output value included both weaned calves and cull cows. Optimum terminal age was mainly a function of PR: 9 yr for average and high PR, but 6 through 9 yr when PR was low, regardless of culling policy or breed groups. Efficiency differences among culling policies were small for high or average PR, but more culling for infertility was beneficial when PR was low. Estimated reductions in unit costs of output value under any culling policy or terminal age were approximately 6% from crossbred cows plus another 6% from crossbred calves, or a total of 12% from specific three-breed crossing of these British breeds. Cost reductions would be somewhat less for rotation crossbreeding but greater for mating smaller crossbred cows with sires of superior growth-carcass breeds.

Heterosis for lifetime production in Hereford, Angus, shorthorn, and crossbred cows.

The effects of maternal heterosis and maternal and grandmaternal breed effects on cumulative lifetime number and weight of calves weaned per cow entering the breeding herd were evaluated for 172 reciprocal crossbred and 156 straightbred cows of the Hereford, Angus, and Shorthorn breeds. Cows born in 1960 and 1961 were developed and mated to calve first at 3 yr of age and those born in 1962 and 1963 at 2 yr of age. Performance under actual culling of cows nonpregnant in two consecutive years and imposed culling of any nonpregnant cows were analyzed. Reproductive rates and weaning weight per calf and per cow exposed increased (P less than .05) as cows advanced from 2 through 5 yr of age, peaked at ages 5 through 9 yr, and decreased from 9 through 12 yr. Effects of heterosis did not interact (P greater than .05) with age at first calving management. During the 12-yr span in the 2-yr-old first-calving management system, crossbred cows produced nearly one more calf than straightbred cows under the actual culling policy (.97 calves, P less than .10) and .82 more calves (P less than .10) if all nonpregnant cows were culled. Corresponding cumulative calf weight weaned was 272 kg (P less than .01), or 25% more, and 232 kg (P less than .01), or 30% more, for crossbred cows than for straightbred cows. The 12-yr cumulative calf weight weaned by straightbred Angus cows exceeded that of Shorthorn cows (P less than .05) and tended to be greater than that of Hereford cows.

Lifetime production of beef heifers calving first at two vs three years of age.

Records of Angus, Hereford, Shorthorn, and first-cross cows born from 1960 to 1963 were used to study the effect of age at first calving and culling policy on cumulative survival (SU), number of breeding seasons (BS), pregnancies (PG), calves born (CB) and alive at 72 h (C72) and at weaning (CW), calf weaning weights (WW), and input/output efficiency, up to 12 yr of age. The 155 cows born in 1960 and 1961 calved first at 3 yr of age (M3) and the 173 born in 1962 and 1963 calved at 2 yr of age (M2). Analyses included both actual culling of cows open in two consecutive years (AC) and imposed culling of any open cow (IC). Also, economic efficiency for no culling (NC) of cows for infertility after first calving and up to 10 yr of age was calculated. The model included cow birth year-sire breed of cow (Y-S), sires within Y-S, breed of cow's dam (D), and D x Y-S. Linear functions of Y-S were used to estimate means for M2 and M3 cows. Under AC, by 12 yr of age M2 exceeded M3 cows by 6.8% SU, 1.1 BS, 1.2 PG, 1.1 CB, 1.0 C72, .9 CW, and 138 kg WW (P less than .10). Under IC, M2 exceeded M3 cows by only .7% SU, .3 BS, .3 PG, .3 CB, .2 C72, and .1 CW; and M3 produced 24 kg more WW than M2 cows (P greater than .10). Economic efficiency was higher for M2 than for M3 cows (greater than 10% at 6 yr to greater than 5% at 12 yr culling age), regardless of culling policy. Economic efficiency was maximum when terminal age of cows was 6 to 9 yr for M2 and 8 to 9 yr for M3 cows. Repeatability of pregnancy was higher (P less than .05) for M3 (19%) than for M2 (2%) cows. Economic efficiency for M2 or M3 cows under NC was slightly poorer (2 to 3%) than under either AC or IC policies. Economic efficiency can be improved by managing heifers to calve first as 2-yr-olds under either mild or intense culling of open cows.

Heterosis for survival and dentition in Hereford, Angus, Shorthorn, and crossbred cows.

Records of 328 Angus, Hereford, Shorthorn, and first-cross cows produced from 1960 to 1963 were used to estimate heterosis (h) and individual (gI) and maternal (gM) average breed effects on cumulative survival (CS) by ages to 12 yr, longevity (L), and size (SI) and condition of incisors at 10 to 15 yr of age. Reasons for cow disposal were also studied. The 155 cows born in 1960 and 1961 first calved at 3 yr of age, and the 173 born in 1962 and 1963 first calved at 2 yr of age. Analyses for CS and L were done for both actual culling of cows open in two consecutive years (AC) and imposed culling of any open cow (IC). The model for CS and L included cow birth year-breed of cow's sire (Y-S), sires within Y-S, breed of dam (D), and D x Y-S. For SI, the model included breed of cow, year of recording, and quadratic effect of age. Linear contrasts were used to estimate h, gI, and gM for quantitative variables, and chi-square was used for discrete variables. Under both AC (P less than .05) and IC, crossbreds exceeded straightbreds in CS to 12 yr (16.7 and 8.5%) and L (1.36 and .99 yr). Estimates of gI and gM for CS and L were generally small, except for the low (P less than .05) gM of Shorthorn cows under IC. Mortality and culling for emaciation, cancer eye, or prolapse was less for crossbreds than for straightbreds and increased with age. Crossbreds had longer (P less than .01) and better (P less than .001) teeth than straightbreds. The longer productive life of crossbred cows reduces rearing costs for replacements and increases sales of calves and cull cows.