Crossbreeding System Research Articles

Interrelationships of heifer milk production and other biological traits with production efficiency to weaning.

Interrelationships among milk production, dam-calf feed efficiency to weaning, and other biological traits were evaluated on 411 first-calf heifers and their calves. Individual feed intakes were measured in a drylot environment for a 1-yr period until weaning of the first calf. Heifer breed types included crossbred Angus-Hereford, Simmental-Hereford, and Tarentaise-Hereford produced in two-breed rotational crossbreeding systems, F1 Salers-Hereford and straightbred Hereford. Production efficiency was defined as cumulative feed ME consumed by the dam-calf pair during the year divided by calf weaning weight. Milk production potential seemed to be unrelated to cow size, adjusted for breed-group effects. Lactational feed energy was increased for dams of increased milk production potential but not enough to offset the increased production of calf weaning weight in terms of production efficiency. Results indicated that increased levels of milk production of heifers were associated with improved production efficiency to weaning. However, the incremental improvement in efficiency per unit of increased milk was less for each additional unit of milk, within the range evaluated. These results are applicable to first-calf heifers that have not yet reached peak age for maximum milk production.

Productivity of pure- and crossbred cattle in a subtropical environment

The influence of different breeds of sire and dam types on cow productivity in an arid, subtropical environment was studied. Cows with calves sired by Simmentaler, Hereford and Bonsmara bulls were more (P less than 0.05) productive than those with calves sired by Afrikaner bulls. Simmentaler sires were superior (P less than 0.05) to Bonsmara sires. Crossbred cows of predominant (greater than 50%) Bos taurus breeding were generally superior to crossbreds of predominant B. indicus breeding and purebreds. Crossbreeding systems to utilize breed effects to optimise cow productivity within environmental constraints are discussed.

Breed and management system effects on feedlot performance and carcass traits (1991)

Eighty nine steers with different proportions of Angus, Hereford, Charolais, Brahman, and Gelbvieh breeding from rotational and terminal crossbreeding systems were produced in Louisiana and finished at KSU. Half of each breed group was placed in the feedlot at weaning (calves) and the other half as yearlings. Half of the each group was slaughtered at a low (0.3-0.4 in.), and the other half at high (0.5 - 0.6 in.) fat thickness. As percentage of Charolais and Gelbvieh breeding increased, feedlot performance improved. As percentage of Charolais, Gelbvieh, and Angus increased, carcass desirability improved. Steers started on feed at weaning were more efficient in feed conversion and were more profitable than those started as yearlings. Age did not affect carcass marbling or quality grade.

Optimal use of nucleus and testing capacity in a pig breeding system with sire and dam lines

In the short term, the total nucleus and testing facilities of a pig breeding organization are fixed, but distributions over sire and dam lines can be varied. The objective of this study was to optimize these distributions. The effects of alternative distributions of nucleus places for sows and testing capacity for boars on total selection response (i.e. sum of the response for reproduction traits in the dam lines and the arithmetic mean of dam and sire line responses for production traits) were studied with a semi-deterministic model. Parameters used in this model were derived from stochastic simulation studies. Annual number of breeding boars was 20 in sire lines and 40 in dam lines. Conclusions (for four-way crossbreeding systems) were as follows: (1) the optimum ratio of sow places for sire lines to sow places for dam lines was about 1:2; (2) the optimum ratio of boar testing capacity for sire lines to boar testing capacity for dam lines was about 1:1; (3) the optimum ratios depended on the total testing capacity relative to the total number of sow places in the nucleus. They were also sensitive to testing system (number of boars tested per litter). Culling rate of boars after test (for conformation or semen quality), crossbreeding system (three-way vs. four-way cross) and annual number of breeding boars had little influence.

Correlation between SI 50 titers of sperm immobilizing antibody and pregnancy rates in sterile women with unknown cause after treatments

Subtle breed differences exist for meat quality traits and the Merino does stand out, although many comparisons are confounded by production site or lack of processing intervention. Despite this, the Merino does seem to have a propensity to produce meat with a higher pH and reduced colour stability under extended ageing. Use of the Merino in a crossbreeding system not only provides benefits from hybrid vigour, but also overcomes the meat quality constraints of pure Merinos. Genetic evaluation for lamb production has enabled impressive genetic gains, but an overemphasis on lean meat production has had to be addressed to counter adverse effects on meat quality traits like eating quality. In this regard, the development of genomic selection has provided a methodology for accurate prediction of genetic merit and applying balanced breeding objectives. The potential for negative meat quality effects has stemmed adoption of non-castration approaches, but ensuring that lamb is young when slaughtered does provide brand integrity.

Evaluating the Use of an Alternative Breed Type as a Pest Management Strategy

AbstractUse of an alternative breed type has been proposed as a management strategy for cow‐calf producers confronted with tick‐infested pastures. The objective of the research reported in this paper is to compare the economics of a Brahman crossbreeding (50 percent Brahman‐50 percent British) system with a British crossbreeding system. Because few estimates of breed differences are available, parametric programming was conducted to evaluate the sensitivity of results to base estimates. The proposed strategy to use Brahman crosses on tick‐infested pastures is economically sound over wide ranges of the parameters considered.

Comparison of Gelbvieh and Limousin Sires in a Terminal Crossbreeding System

Comparison of Gelbvieh and Limousin Sires in a Terminal Crossbreeding System

Economic evaluation of alternative crossbreeding systems involving four breeds of swine. I. The simulation model.

A static, deterministic computer model, programmed in Microsoft Basic for IBM PC and Apple Macintosh computers, was developed to calculate production efficiency (cost per kg of product) for nine alternative types of crossbreeding system involving four breeds of swine. The model simulates efficiencies for four purebred and 60 alternative two-, three- and four-breed rotation, rotaterminal, backcross and static cross systems. Crossbreeding systems were defined as including all purebred, crossbred and commercial matings necessary to maintain a total of 10,000 farrowings. Driving variables for the model are mean conception rate at first service and for an 8-wk breeding season, litter size born, preweaning survival rate, postweaning average daily gain, feed-to-gain ratio and carcass backfat. Predictions are computed using breed direct genetic and maternal effects for the four breeds, plus individual, maternal and paternal specific heterosis values, input by the user. Inputs required to calculate the number of females farrowing in each sub-system include the proportion of males and females replaced each breeding cycle in purebred and crossbred populations, the proportion of male and female offspring in seedstock herds that become breeding animals, and the number of females per boar. Inputs required to calculate the efficiency of terminal production (cost-to-product ratio) for each sub-system include breeding herd feed intake, gilt development costs, feed costs and labor and overhead costs. Crossbreeding system efficiency is calculated as the weighted average of sub-system cost-to-product ratio values, weighting by the number of females farrowing in each sub-system.

Economic evaluation of alternative crossbreeding systems involving four breeds of swine. II. System efficiency.

A static, deterministic computer model was used to calculate production efficiency (cost per kg of product) for four purebred and 69 alternative crossbreeding systems involving the Duroc, Yorkshire, Landrace and Spotted breeds of swine. Crossbreeding systems were defined as including all purebred, crossbred and commercial matings necessary to maintain a total of 10,000 farrowings. Driving variables for the model were predicted mean conception rates, litter size born, preweaning survival rate, postweaning average daily gain, feed-to-gain ratio and carcass backfat. Predictions were computed using breed effect and heterosis estimates obtained from experimental data involving the four breeds collected at the Oklahoma Agricultural Experiment Station between 1976 and 1979. The most efficient breed combinations for each of the nine types of crossbreeding systems evaluated were predicted to reduce cost per kg of product by 6.7 to 10.5%, relative to the most efficient purebred (Duroc). The Duroc X (Yorkshire, Landrace, Spotted) four-breed rotaterminal was predicted to be the most efficient system, followed by the Duroc X (Yorkshire, Landrace) rotaterminal. Duroc X (Spotted X Landrace) and Duroc X (Spotted X Yorkshire) static systems ranked third and fourth overall, respectively. Sensitivity analysis indicated that ranking of systems predicted to be most efficient under the default model was reasonably robust to varying input economic, genetic and management parameter values. Results of this study suggested that three- or four-breed rotaterminal or static systems should maximize effective use of heterosis and breed complementarity in swine production systems.

Effects of using sires selected for yearling weight and crossbreeding with beef and dairy breeds: birth and weaning traits.

Data consisting of 948 calf records collected from 1978 to 1982 were analyzed to determine the effects of breeding methods used to improve commercial herds genetically on birth and weaning traits. Four distinct groups were used in the project: Group 1 (G1), an unselected, random mating Hereford control line; Group 2 (G2), a Hereford group using sires selected for yearling growth; Group 3 (G3), a rotational cross with Angus, Hereford, Charolais and Simmental breeds; and Group 4 (G4), a rotational cross with Angus, Hereford, Simmental and Holstein-Friesian breeds. Traits analyzed were birth weight (BW), calving difficulty (CD), percent assisted births (%AB), percent born alive (%BL), preweaning average daily gain (PWDG), relative growth rate (RGR), weaning weight (WWT) and percent weaned (%WND). The use of high yearling weight sires in G2 increased calf size (P less than .01) at birth and weaning by 8.9 and 28.1 kg, respectively, along with increased CD (P less than .01). Use of rotational crossbreeding systems increased calf size and growth from birth to weaning (P less than .01), but decreased CD and %AB (P less than .01) by .17 units and 13.5%, respectively. Including Holstein-Friesian in G4 resulted in further increases in preweaning growth (P less than .01) and calving ease was improved without affecting BWT compared with G3.

Inheritance of vertical fiber hide defect in cattle.

Inheritance of vertical fiber hide defect (VFHD), a structural defect in collagen fiber orientation that causes weakness and reduced value of leather, was examined using histological data on hide biopsies obtained from 465 Hereford cattle by 65 sires. The data set included 44 offspring-dam pairs, for which VFHD phenotypes had been diagnosed on both the offspring and dam. Examination of offspring and parental frequency distributions indicated that inheritance of the condition was likely to be due to an autosomal recessive. In a subsequent experiment, a Hereford bull with a known VFHD phenotype was mated to Hereford cows with known VFHD phenotypes and to Angus cows not showing the defect. Angus were chosen because the defect has never been observed in the breed. All offspring (5) resulting from VFHD X VFHD matings expressed the defect, while no offspring (12) out of VFHD X non-VFHD matings (Angus cows) expressed the defect. It was concluded that VFHD is inherited as an autosomal recessive. The role that selection and alternative crossbreeding systems can play reducing phenotypic frequency of the defect is discussed.

Swine Genetic Evaluation and Selection Programs12

Summary Swine selection procedures which utilize not only each animal’s performance but also performance of relatives can potentially increase the rate of genetic improvement by increasing the accuracy of selection. Four criteria are: (1) accurate evaluation of both young and old males and females, (2) timeliness of data analysis and summarization, (3) ability to account for possible biases including prior genetic selection and assortative mating, and (4) practical considerations concerning computer memory requirements and cost. Best linear unbiased prediction (BLUP) procedures provide accurate predictions of genetic merit by simultaneously predicting breeding values and adjusting for fixed effects. Simplified BLUP procedures including the reduced animal model (RAM) with recursive prediction or SHORT-CUT BLUP provide accurate genetic evaluation with reduced computer memory requirements. Multivariate BLUP can be simplified or reduced by the use of canonical transformations. The use of multivariate BLUP genetic evaluations in conjunction with quadratic bioeconomic objectives should result in the selection criteria which will maximize selection response. Seedstock producers should select their replacements relative to the intended use of their descendants in commercial crossbreeding systems. For this reason, three indexes are suggested: a terminal sire, general, and dam-breed (maternal) objective. With the implementation of a comprehensive genetic program, alternative selection programs including the intense selection of dams for a maternal objective can further increase genetic progress.

Methods of analysing the effect of season of birth on weaning weight in a zebu × temperate beef herd in Kenya

ABSTRACTA study was made of weaning weights in a beef herd, using a rotational crossbreeding system including the Boran breed (zebu) and two temperate beef breeds (Devon and Limousin), and a seasonal calving period spanning the onset of the rains.Significant sources of variation in calf weaning weights were crossbred type, age at weaning, sex, dam's age, season of birth, year and a year × crossbred type interaction (all P < 0·001).The adjusted mean weaning weight was 203 kg. Weaners sired by a temperate bull were generally 1·08 times the weight of those sired by a zebu bull. Steers were 1·06 times the weight of heifers. Marked increases in weaning weights occurred as dams increased in age from 3 to 6 years and slight increases continued up to 9 years of age. Weaners born to 9-year-old cows were 1·09 times the weight of those from first calvers.Alternative methods for investigating the effect of season of birth were examined and the final choice was a covariate for time from birth to the onset of the rains. Calves born in the earliest part of the calving period were approximately 1·14 times the weight of those born just after the onset of the rains.

Breeding and Production of Beef to Optimize Production Efficiency, Retail Product Percentage and Palatability Characteristics

The demand trend for beef with a higher percentage of lean is expected to continue at an accelerated rate. The trend toward more complete centralized processing at or near the point of slaughter will accelerate in order to gain efficiencies in transportation and labor and to add attractiveness and convenience to the product. Differences in efficiency of production of weaned calf weight are generally independent of cow size provided the nutritive environment is adequate to support reproduction. Maintenance requirements are greater for protein than for fat tissue. Differences in maintenance requirement are small between animals of the same weight and body composition. There is no evidence to support the concept that large genetic differences exist in shape of the growth curve if growth is considered on a fat free basis. Rank of different biological types of growing-finishing cattle in regard to feed efficiency is dependent upon interval of evaluation (time constant, gain constant or fat constant). Reducing the percentage of nutrients contributed by concentrate feed resources by one-half will result in little or no loss in beef palatability or in weight of retail product produced. More than 80% of the increased weight gain resulting from dietary energy densities above 2.7 Mcal metabolizable energy/kg dry matter is fat in growing-finishing steers. Yearling steers slaughtered off pasture without any concentrate feeding had longissimus muscle with lower palatability than steers fed concentrate feeds. However, after a feeding period of 49 d after removal from pasture, palatability characteristics of longissimus muscle were equal to those from steers fed for much longer periods. Differences in marbling score account for less than 10% of the variation in palatability attributes of young cattle produced in economically viable systems. Simultaneous selection for percentage of retail product and marbling score will not be effective for either character. When wholesale cuts are trimmed to a uniform degree of fatness as retail product, genetic differences in retail product percentage contributed by each wholesale cut are too small to justify a selection objective of increasing the percentage of the more preferred cuts. Crossbreeding systems to use both heterosis and complementarity can increase calf weight weaned by 7.75 to 12.1% with no increase in feed resources and with a small reduction in number of females in the beef breeding herd. Intact males produce 38% more edible product than castrate males/unit of digestible energy consumed. Much of the potential improvement in biological efficiency of beef production from growth, composition and reproduction is obtainable through heterosis and complementarity in crossbreeding systems and through production of intact males.

Rotation Crossbreeding with Sahiwal and Ayrshire Cattle in the Tropics

Data were analyzed for two breeding groups of cattle that were either 67% Sahiwal-33% Ayrshire or 33% Sahiwal-67% Ayrshire produced in a continuous two-breed rotation crossbreeding system at sea level on the Indian Ocean in Kenya at 003.5° latitude south. Characters in the analysis were age at first calving, calving interval, lactation yield, annual lactation yield, birth weight, average daily gain from birth to 50kg, average daily gain from 50 to 90kg, average daily gain from birth to 90kg, and calf survival. The 33% Sahiwal-67% Ayrshire breeding group had a significant advantage over the 67% Sahiwal-33% Ayrshire breeding group in all characters except calf survival, calving interval, and birth weight.

Crossbreeding in Beef Cattle: Evaluation of Systems1

Summary The basic objective of beef cattle crossbreeding systems is to optimize simultaneously the use of both nonadditive (heterosis) and additive (breed differences) effects of genes. Experimental results evaluating rotational crossbreeding systems indicate that high levels of heterosis are sustained in successive generations and that the relationship between loss of heterosis and loss of heterozygosity approaches linearity. Major differences among breeds have been demonstrated for most characters that contribute to production efficiency. Results based on both experimentation and computer simulation indicate that differences in additive genetic merit of breeds for specific characters can be used in specific crossbreeding systems to synchronize genetic resources with other production resources and to provide for complementarity through terminal sire breeds. Rotational crossbreeding systems have the advantage of using heterosis in all females and progeny in a self-contained commercial herd; however, fluctuation between generations in additive genetic composition relll~es use of breeds that are generally compatible. This requirement restricts the use that can be made of breed differences to synchronize germ plasm resources with other production resources and eliminates the use of complementarity other than in a combined breed-rotation, terminal-sire system. A static terminal-sire crossbreeding system provides opportunity to synchronize germ plasm resources with other production resources in about 50% of the cow herd, to use maximum (FI) heterosis in about 67% of the calves marketed and to use complementarity in

Effective crossbreeding systems utilizing Zebu cattle.

The basic objectives and procedures for successful crossbreeding of beef cattle were considered, with special reference to the levels of realized hybrid vigor that might be anticipated for different crossbreeding programs involving the American Brahman (Z1) and European (Ej) breeds. Intralocus heterozygosis levels with respect to breed origin of genes (breed heterozygosis) were computed for various crossbreeding systems. These values were weighted by approximate relative F1 heterosis levels for different breed combinations (1.0 for Z1Ej and .3 for E1E2) to yield the estimated relative hybrid vigor levels for total performance in alternative crossbreeding systems. The estimated average maternal heterosis levels for the various systems, were respectively 0, 33, 67, 66, 50, 54 and 49% for production of F1 (EZ) calves, three-breed terminal cross calves, two-breed-of-sire (E1--Z1) rotation crosses, three-breed-of-sire (Z1--E1--E2) rotation crosses, two-breed (Z X E) synthetics, three-breed (Z1 X E1E2) synthetics and four-breed (Z1E1 X E2E3) synthetics. The respective values for calf heterosis levels were 50, 57, 67, 66, 50, 54 and 49%. Successful crossbreeding requires (1) the choice of appropriate breed combinations for the environment and production system management programs to support the increased production potential or crossbred cattle.

Effect of type of breed and crossbreeding system on beef cattle performance under extensive and intensive production conditions in a subtropical environment1

Effect of type of breed and crossbreeding system on beef cattle performance under extensive and intensive production conditions in a subtropical environment¹

The basis of crossbreeding in pigs; A review

A survey of the different parameters involved in crossbreeding is given following the analysis of Dickerson (1969). The genetic gain resulting from crossbreeding has a double origin: complementarity and heterosis. The practical importance of these two advantages is evaluated in swine. Average individual ( H 1) and maternal ( H M ) heterosis effects on main performance traits are derived from experimental estimates summarized in graphs; the expected fraction of H I and H M utilized in some crossing plans is given. It appears that heterosis accounts for the major part of the gain from crossing in swine. The observed variation between estimates of heterosis for a given trait is analyzed: the effects of sampling variance, specific combining ability of some crosses, heterosis by environment interactions and association between heterosis and parental mean are considered and some illustrations are given. Finally the different criteria used in optimization of crossing between available pig breeds are reviewed. The present trend is to pay attention not only to the final cross but to the whole crossbreeding system, either as static (at demographic equilibrium) or dynamic (transition phase from another system). The first results of such a study with two French breeds are given briefly.

EFFECTS OF REPRODUCTIVE PERFORMANCE AND MATING SYSTEM ON FARM GROSS MARGINS IN BEEF PRODUCTION

A linear programming model for beef production was used to examine the effects of straightbreeding, three-breed rotational and terminal crossbreeding systems on farm gross margins at each of three reproductive rates. Terminal crossing systems that maintained a similar distribution of livestock classes in the herd as in rotational crosses (TM) and that fed all terminal cross heifers in the feedlot (T7) were examined. A farm level model was used, incorporating cows, replacement breeding females, feedlot steers and heifers and cropping with their requirements for labor and capital. In both terminal crossing systems replacement breeding females were purchased at 7 mo of age. Several combinations of the following four factors were considered: cow weights, estimates of heterosis, limitations on farm resources and prices of beef relative to feed. Calf crop percentages ranged from 68.4 to 89.7% for various combinations of reproductive rate and mating system. Higher reproductive rates produced higher farm gross margins from straightbreeding, rotational and TM terminal crosses, but the size of the increase depended on the particular combination of the four factors considered. The effect of reproduction was inconsistent for the T7 terminal crossing system, probably due to changes in age distribution of females. Compared with rotational crosses, farm gross margins for TM terminal crosses were little different when no complementarity for size was considered (< 1.0%), although superior on the average. When the terminal cross calves were sired by larger bulls mated to smaller cows, the TM system produced larger farm gross margins than the rotational system (17% on average). At the livestock prices used, T7 produced larger farm gross margins than TM due to a more complete use of farm resources, differences ranging from $4,985 to $11,660 relative to farm gross margins for TM of $14,954 and $13,401, respectively. Increases in sizes of cows in the rotational crossing and straightbreeding systems and of both sire and dam in the T7 terminal crossing system produced higher farm gross margins. Changes in estimates of heterosis used, beef to feed price ratios and farm resource situations did not in general produce changes in rankings of the mating systems. Interactions were, however, found for some particular combinations of reproductive rate, farm resources and beef to feed price ratios.