Choice Of Breed Research Articles

Genetic Variability of Lactoferrin Content Estimated by Mid-Infrared Spectrometry in Bovine Milk

The effects of lactoferrin (LF) on the immune system have already been shown by many studies. Unfortunately, the current methods used to measure LF levels in milk do not permit the study of the genetic variability of lactoferrin or the performance of routine genetic evaluations. The first aim of this research was to derive a calibration equation permitting the prediction of LF in milk by mid-infrared spectrometry (MIR). The calibration with partial least squares on 69 samples showed a ratio of standard error of cross-validation to standard deviation equal to 1.98. Based on this value, the calibration equation was used to establish an LF indicator trait (predicted LF; pLF) on a large number of milk samples (n = 7,690). A subsequent study of its variability was conducted, which confirmed that stage of lactation and lactation number influence the overall pLF level. Small differences in mean pLF among 7 dairy breeds were also observed. The pLF content of Jersey milk was significantly higher than that in Holstein milk. Therefore, the choice of breed could change the expected LF level. Heritability estimated for pLF was 19.7%. The genetic and phenotypic correlations between somatic cell score and pLF were 0.04 and 0.26, respectively. As somatic cell score increases in presence of mastitis, this observation seems to indicate that pLF, or a function of observed pLF, compared with expected LF might have potential as an indicator of mastitis. The negative genetic correlation (−0.36) between milk yield and pLF could indicate an undesirable effect of selection for high milk production on the overall LF level.

Ownership of High-Risk (“Vicious”) Dogs as a Marker for Deviant Behaviors

This study examined the association between ownership of high-risk ("vicious") dogs and the presence of deviant behaviors in the owners as indicated by court convictions. We also explored whether two characteristics of dog ownership (abiding licensing laws and choice of breed) could be useful areas of inquiry when assessing risk status in settings where children are present. Our matched sample consisted of 355 owners of either licensed or cited dogs that represented high or low-risk breeds. Categories of criminal convictions examined were aggressive crimes, drugs, alcohol, domestic violence, crimes involving children, firearm convictions, and major and minor traffic citations. Owners of cited high-risk ("vicious") dogs had significantly more criminal convictions than owners of licensed low-risk dogs. Findings suggest that the ownership of a high-risk ("vicious") dog can be a significant marker for general deviance and should be an element considered when assessing risk for child endangerment.

Relative resistance of willow and poplar biomass production clones across a continuum of herbivorous insect specialization: Univariate and multivariate approaches

Short-rotation woody crops (SRWC) are being developed as a sustainable system that simultaneously produces a renewable feedstock for bioenergy and bioproducts and a suite of environmental and rural development benefits. However, damage from defoliating insects can significantly reduce the yield of SRWC and negatively impact their sustainability. Information regarding the relative resistance to defoliation of different SRWC clones is not only useful for deployment and breeding choices, but can also help elucidate ecological patterns of herbivore specialization. Laboratory feeding bioassays tested the resistance of 19 willow ( Salix spp.) and six poplar ( Populus spp.) biomass production clones to feeding by seven common folivorous insects. Defoliation was measured using a leaf area meter and results were standardized according to leaf area consumed per insect per day. Significant differences in resistance were found among clones ( p ≤ .05). The most folivore-resistant groups included the six poplar clones and willow clones SH3, SP3, S546 and S625. Willow clones with S. eriocephala or S. dasyclados parentage were generally less resistant to herbivory than those with other parentages. Comparisons of univariate and multivariate approaches found that the multivariate techniques are robust and conservative, and provide an efficient means of screening a large number of clones in a development program. The multivariate approach provided a clearer sorting of folivores along a continuum of insect specialization. Such sorting may be useful in selecting model folivores to use in tree genetic improvement screening systems to efficiently reveal which clones are more likely to be resistant to multiple insect pests.

A novel method for the estimation of the relative importance of breeds in order to conserve the total genetic variance

The need for conservation of farm animal genetic resources is widely accepted. A key question is the choice of breeds to be conserved. For this purpose, a core set of breeds was introduced in that the total genetic variance of a hypothetical quantitative trait was maximised (MVT core set). For each breed the relative contribution to the core set was estimated and the breeds were ranked for conservation priority according to their relative contribution. The method was based on average kinships between and within breeds and these can be estimated using genetic marker data. The method was compared to a recently published core set method that maximises the variance of a hypothetical population that could be obtained by interbreeding the conserved breeds (MVO core set). The results show that the MVT (MVO) core set favours breeds with a high (low) within breed kinship that are not related to other breeds. Following this, the MVT core set method suggests conserving breeds that show a large difference in the respective population mean of a hypothetical quantitative trait. This maximises the speed of achieving selection response for this hypothetical selection direction. Additionally, bootstrap based methods for the estimation of the breed's contribution to the core sets were introduced, substantially improving the accuracy of the contribution estimates.

Product quality attributes associated with outdoor pig production

Outdoor pig production offers animals increased environmental diversity and behavioural freedom but imposes challenges for breed adaptation, management control, biosecurity, and environmental protection. Each of these issues has potential implications for the real and perceived quality of the product. In most conventional Northern European production systems, only adult and suckling animals are at pasture. However, in traditional Mediterranean systems and in organic production systems, meat animals may be maintained outdoors throughout their lives. Major influences on organoleptic quality of product derive from the choice of breeds most appropriate to outdoor systems, modifications to growth rate, and the increased proportion of forage in the diet. Indirect consequences may also result from both positive and negative influences on physiological stress responses in the pre-slaughter period. Whilst some aspects of animal health and hygiene may be improved in more extensive conditions, exposure to parasites and to contact with wildlife may increase zoonotic infection risk. Perceptual attributes of product quality may be either positively or negatively influenced, depending on the ethical attitudes of consumers and the quality of management and husbandry in outdoor pig units which are visible to the public. The extent to which real and perceived differences in product quality are reflected in changed economic value is more a function of marketing than production system.

A novel method for the estimation of the relative importance of breeds in order to conserve the total genetic variance

The need for conservation of farm animal genetic resources is widely accepted. A key question is the choice of breeds to be conserved. For this purpose, a core set of breeds was introduced in that the total genetic variance of a hypothetical quantitative trait was maximised (MVT core set). For each breed the relative contribution to the core set was estimated and the breeds were ranked for conservation priority according to their relative contribution. The method was based on average kinships between and within breeds and these can be estimated using genetic marker data. The method was compared to a recently published core set method that maximises the variance of a hypothetical population that could be obtained by interbreeding the conserved breeds (MVO core set). The results show that the MVT (MVO) core set favours breeds with a high (low) within breed kinship that are not related to other breeds. Following this, the MVT core set method suggests conserving breeds that show a large difference in the respective population mean of a hypothetical quantitative trait. This maximises the speed of achieving selection response for this hypothetical selection direction. Additionally, bootstrap based methods for the estimation of the breed's contribution to the core sets were introduced, substantially improving the accuracy of the contribution estimates.

A simulation exercise to teach principles of bovine reproductive management.

Students in Reproductive Management (a senior-level course with approximately 20 to 50 students per semester) at the University of Missouri-Columbia are required to participate in a simulation exercise that is designed to improve reproductive efficiency in a beef herd. During a simulated 5-yr period, students must 1) improve reproductive efficiency in a beef cow-herd through implementation of reproductive management principles; 2) determine the economic impact of reproductive management decisions in a beef herd; and 3) evaluate the constraints of different geographical locations on approaches to reproductive management. Groups of three to four students are provided with the reproductive and economic records of a farm/ranch located in different parts of North America. Students create reproductive management plans consisting of 1) detailed discussion of farm/ranch environment (climate, terrain, forage and grain availability, and stocking rate; season for breeding and calving; and justification for choice of breed); 2) assessment of current level of reproductive performance; 3) identification and economic justification of specific (measurable) objectives; 4) discussion of alternatives for accomplishing specific objectives; 5) prediction of reproductive performance (pregnancy rate, quantity of calf weaned per cow exposed, and cost per quantity of calf weaned) in response to implementation of specific management practices; and 6) an annual and 5-yr reproductive and economic summary. Students obtain livestock marketing information for their assigned location via the Internet. Spreadsheets were developed to calculate the reproductive efficiency of postpartum cows and replacement heifers based on management decisions made by the groups and to calculate a yearly economic summary for each of the 5 yr. Management decisions are justified in a written report, and oral presentations are given to the class when the project is completed. Greater than 85% of students indicated that the exercise increased their understanding of how management decisions affect reproductive efficiency and profitability in a beef operation and also provided added confidence for students that applied for beef management positions.

Manipulation of Olfactory Signaling and Mate Choice for Conservation Breeding: a Case Study of Harvest Mice

Abstract: Mate choice by females can introduce difficulties to captive breeding programs because there may be a conflict between the conservation manager's choice of mate (based on random allocation or maximizing heterogeneity) and the females' own preferences, often resulting in incompatibility and aggression. Similar effects are caused by inappropriate social contexts at the time of pairing. We manipulated the social experience of male and female harvest mice (Micromys minutus) to investigate whether we could enhance compatibility between randomly allocated mates by altering female preferences. In one experiment, we used a choice test to identify female preferences between two males and then varied the competitive context of unpreferred males by transferring competitor's scent marks into their cages. The manipulation caused them to increase their investment in a form of olfactory signaling (scent marking), which female rodents use as an indicator of male quality when choosing mates. The manipulation increased their attractiveness relative to the initially preferred male when the choice test was repeated. In a second experiment, we tested the effect of females' familiarity with the odor of males by transfer of male scent marks to female cages. Females preferred familiar males in choice tests and were less aggressive toward them when pairs were introduced than females paired with unfamiliar males. This kind of approach can influence mate choice, and transferring scent marks between cages or collections is an effective and practical behavioral means of improving success in conservation breeding programs.

Deterministic predictions of beef cow herd population dynamics with alternative replacement strategies

AbstractA deterministic method of predicting numbers of each animal class present over time in a beef cow herd with multiple calving seasons per year is described. Breeding cow classes are defined according to the number of generations of descent from the cows in the herd prior to the introduction of a specific heifer replacement breeding policy. Cow classes are further divided into subgroups defined according to age of cow, calving interval and whether or not the cow was last mated to a terminal sire. The method is demonstrated by showing the evolution of herd breed make-up with several alternative replacement female breeding policies including grading-up, two-breed rotation and three-breed rotation breeding policies. For an example herd, the first generation of replacements peaked at approximately 0·4 of the herd at 6 years after the first matings for a new breeding system. Later generations of replacements reached equivalent proportions of the herd to the previous generation approximately 3·3 years later, with peak proportions at approximately 0·25 of the herd. Differences in the relative levels of expression of heterosis for grade up versus rotational replacement policies increased steadily from 5 years onwards with 0·17 of the heterosis expected in a herd of F1 cows remaining 20 years after the first matings of the new breeding system. The two-breed grading-up system showed less heterosis than the three-breed grading-up system only after 8 years, with the difference increasing to 0·16 of the heterosis in an F1 herd after 20 years. Results are also presented showing the difference in contributions of breeds to the herd gene pool over time with the different breeding systems. With the rotational systems, breeds lag by approximately 3 years in the timing of their contribution according to the order of their introduction to the rotation. The effects of faster heifer replacement rates on results were also discussed. It is concluded that short-to medium-term impacts of breed and replacement breeding system choices are likely to be more relevant in practical decision making by suckler herd managers than the characteristics of breeding systems once herds have reached genetic equilibrium.

'Liaofu', A New Early Apple

Many early apple (Malus ×domestica Borkh.) cultivars exist, including ‘Yellow Transparent’ and ‘Red Astrachan’, both with fruit growth periods (FGP) of 70 d. However, both yield poorly and the fruits are very sour. ‘Summer Green’ from Japan has an FGP of ≈80 d, and has good fruit quality. ‘Geneva Early’ from the United States ripens in 67 to 70 d, but produces small fruit that ripen unevenly and tend to drop heavily near harvest (Qiao et al., 1980; Yang et al., 1987). Since 1950, Chinese apple breeders have developed many early cultivars that are better than ‘Yellow Transparent’. Of these, ‘Liaofu’ is the best, has the shortest FGP (60 d), and combines disease resistance with good quality. We believe it to be superior to other commercial, early-ripening cultivars, and the best choice for both marketing and breeding.

The effect of crossbred ewe type and ram genotype on lamb output and carcass quality

In view of the stratified nature of the sheep industry, changes in breeding policies in the hill sector impinge on the performance of the lowland sector. Carson et al (2000) investigated the effect of choice of ram and ewe breed on lamb output and carcass quality in the hill sheep sector. First cross (F1) ewes were produced as a result of crossing Scottish Blackface and Cheviot ewes with a range of ram breeds. The primary objective of the present study was to provide information on the performance of these crossbred females in terms of lamb output and carcass quality and thus determine the impact of changing hill genetics on all strata of the sheep industry. Within the terminal sire breeds significant improvements in lean growth potential have been made through genetic improvement schemes. The secondary objective of this study was to provide information on the effects of using high lean growth index rams on lamb growth and carcass quality.

Direct and maternal genetic effects on birth and weaning traits in multibreed cattle data and predicted performance of breed crosses.

Direct and maternal additive effects and heterosis were estimated using data from straightbred Angus, Brahman, Charolais, Hereford, and four generations of rotational crosses among these breeds. Traits of interest were birth weight, Julian day of birth, average daily gain from birth to weaning, 205-d weight, and weaning weight per cow exposed. Complete data were available on 3,445 calves produced from 4,733 matings. Discrete generations of 4-yr duration were produced from 1970 through 1988. Brahman was included in each rotational crossbreeding system. Genetic effects were estimated by regression. Direct and maternal additive effects of Brahman, Charolais, and Hereford were estimated as deviations from Angus. Direct and maternal heterosis effects were assumed proportional to expected heterozygosity. The Brahman direct additive effect resulted in later-born calves (P < 0.01). Brahman, Charolais, and Hereford direct additive effects increased birth weight, and the Brahman maternal additive effect decreased birth weight compared with Angus (P < 0.05). Charolais direct and maternal additive effects were greater than Angus for average daily gain and 205-d weight (P < 0.01). The Hereford maternal additive effects on average daily gain and 205-d weight were less than those of the other breeds (P < 0.01). Breed combinations including Brahman had greater direct heterosis for birth weight, average daily gain, and 205-d weight than other combinations (P < 0.01). Angus, Charolais, and Hereford direct additive effects on weaning weight per cow exposed were greater than Brahman (P < 0.05). Predicted average daily gain, 205-d weight, and weaning weight per cow exposed were, on average, greater in four-breed rotation systems than in three- and two-breed systems. Among two-breed rotation systems, predicted average daily gain and 205-d weaning weight were greatest for Charolais-Brahman and least for Angus-Hereford. Calves from the Angus-Charolais-Hereford system weighed less at weaning than any other three-breed combination. However, weaning weight per cow exposed from the Angus-Charolais-Hereford system was greatest among three-breed systems. Within three- and four-breed rotation systems, ranges in predicted birth and weaning weights among generations varied by up to 10.0 and 25.2 kg, respectively. The choice of breeds affects performance, and the sequence of their use may affect intergenerational variation in performance.

Evaluation of the growth performance and carcass characteristics of lambs produced in Quebec

Data for a total of approximately 1100 lambs tested in 12 trials from 1992 to 1995 in commercial lamb test stations in Quebec were used to determine the effect of sex, sire breed and genetic type on growth performance and carcass characteristics. Lambs were housed two to a pen and fed commercial diets. Maximum test length was 112 d. Lambs were slaughtered when their liveweight was approximately 47 ± 5 kg for the males and 43 ± 4 kg for the females. Feed intake and growth rate were measured during the test, and carcass measurements were taken at slaughter and at 24 h following slaughter. Feed intake was the average for the pen, while the growth and carcass measurements were taken individually. Males ate more per day, had better gain and were younger at slaughter than females. Females had more body fat and better carcass conformation scores than males. However, males did not have a greater loin muscle thickness compared to females. Lambs sired by Hampshire or Suffolk rams had superior growth performance and leaner carcasses than lambs sired by Dorset rams. However, Hampshire and Suffolk-sired lambs did not have a greater loin muscle thickness compared to Dorset-sired lambs. Analysis of different genetic types did not demonstrate a pronounced effect on lamb performance. No specific genetic composition was clearly superior to the others for the various variables studied. Genetic quality within a breed of sheep bought or kept for reproduction is as important as the choice of breed or the combination of breeds. Key words: Lamb, growth performance, carcass composition

Application of a computer model to predict optimum slaughter end points for different biological types of feeder cattle.

A bioeconomic model was developed to predict slaughter end points of different genotypes of feeder cattle, where profit/rotation and profit/day were maximized. Growth, feed intake, and carcass weight and composition were simulated for 17 biological types of steers. Distribution of carcass weight and proportion in four USDA quality and five USDA yield grades were obtained from predicted carcass weights and composition. Average carcass value for each genotype was calculated from these distributions under four carcass pricing systems that varied from value determined on quality grade alone to value determined on yield grade alone. Under profitable market conditions, rotation length was shorter and carcass weights lighter when the producer's goal was maximum profit/day, compared with maximum profit/rotation. A carcass value system based on yield grade alone resulted in greater profit/rotation and in lighter and leaner carcasses than a system based on quality grade alone. High correlations ( > .97) were obtained between breed profits obtained with different sets of input/output prices and carcass price discount weight ranges. This suggests that breed rankings on the basis of breed profits may not be sensitive to changes in input/output market prices. Steers that were on a grower-stocker system had leaner carcasses, heavier optimum carcass weight, greater profits, and less variation in optimum carcass weights between genotypes than steers that were started on a high-energy finishing diet at weaning. Overall results suggest that breed choices may change with different carcass grading and value systems and postweaning production systems. This model has potential to provide decision support in marketing fed cattle.

A time-dependent bioeconomic model of commercial beef breed choices

The breed choice decision requires simultaneous consideration of both economic and physical relationships in light of the multi-year, multi-product nature of commerical cow-calf production. To accomplish this a time-dependent bioeconomic model of cow-calf production was developed in which both physical output-input relationships and production decisions are expressed in terms of cow age and stage of production. The breed choice and optimal herd distribution (culling age and proportion by age) decisions are then cast within the economic framework of maximizing net returns per unit of nutrient resource derived from a fixed land area. The resulting bioeconomic model is easily solved, as illustrated by an empirical example evaluating 16 alternative breed choices for a representative West Texas ranch. Results indicate a marked economic preference for smaller, higher productivity animals, such as Sahiwal. Conversely, large, slow maturing breeds with marginal reproductive capacity, such as Charolais, are least profitable for the fixed resource area defined.

Herbage intake, liveweight gain, and grazing behaviour of Friesian, Piedmontese × Friesian, and Belgian Blue × Friesian bulls

Abstract The introduction of heavily muscled breeds of cattle has provided New Zealand farmers with a wider breed choice, but no data on the performance of these breeds, relative to the Friesian for bull beef production on pasture are available. Thirty Friesian, Piedmontese × Friesian, and Belgian Blue × Friesian bulls were purchased at 3 months of age and farmed to slaughter at 18–20 months of age. Herbage intake was recorded over 18 days when the heaviest group of bulls was 15 months old. Herbage intake (kg DOMI/head per day) was similar for the three breeds under continuous stocking on a ryegrass-white clover sward maintained at a sward surface height of 8–10 cm. The Belgian Blue × Friesian bulls had lower biting rates (P < 0.05) and spent more time idling than the other two genotypes. There was no difference in the rate of liveweight gain over the intake measurement period, or in final liveweight between the genotypes. Bulls of the heavily muscled genotypes both had higher rates of carcass and meat ga...

Quantitative genetic studies in flue-cured tobacco (Nicotiana tabacum). III. Inheritance of phenolic constituents

Genetic analyses of major phenolic constituents of flue-cured tobacco (Nicotiana tabacum L.), utilizing Griffing's method II model II and Hayman's Wr–Vr graphic analysis on a five-parent diallel set excluding reciprocals, were conducted in a replicated randomized block design over a 2-year period at the Delhi Research Station. The ANOVA for general and specific combining ability and Wr–Vr graphic analysis indicated genetic control for these phenolics. Additive genetic variance was the predominant contributor in the expression of chlorogenic acid and its isomers, scopoletin, scopolin, and rutin; dominance where present was in the partial dominance range. The role of nonallelic interaction was negligible for all variables except scopoletin and rutin. Tannins consisting of chlorogenic acid and its isomers were under dominant gene control, while the coumarins, scopoletin, and scopolin, and the flavonoid rutin were under recessive gene control. A considerable degree of positive pleiotropic effect was exhibited by all phenolic constituents except scopoletin where negative correlations were prevalent. Breeding procedure and choice of parents are discussed in manipulating pheolics.Key words: quantitative genetics, tobacco, Nicotiana, phenolics.

The Choice of Sheep Breeds on hill and Upland Farms

The Choice of Sheep Breeds on hill and Upland Farms

Growth Relationships Associated with First Conception and Calving of Beef Heifers on Bermuda-Fescue Pasture

Over 3 years, 332 virgin straightbred and crossbred heifers were exposed to natural service from seven breeds of bulls for 90-day breeding seasons. Two-hundred and twelve heifers calved and 120 did not, for a calving rate of 63.9%. For those heifers calving, age at conception was estimated from calving dates and related to an estimated weight at conception and to various pre- and postweaning weights and gains. Weaning, fall and spring weights of heifers calving were approximately 7.0, 10.0 and 12.0% greater, respectively, than those of heifers not calving. Average age and weight at conception were 492 days and 277 kg, respectively. Small differences among breeding groups in calving rate were attributed to failure of the pasture regimens to provide sufficient nutrients for growth and reproduction of the larger framed heifers. Year, sire breed and dam breeding influenced (P<.01) estimated weight at conception. Age at conception was not influenced by these effects but was influenced (P<.01) by the interactions of year × dam breed and sire breed × dam breed. The pre-weaning period was the most important period of growth in determining weight at conception. In the preweaning period, each .1-kg increase in daily gain increased weight at conception by 19.3 kilograms. Gain during the three periods of growth studied did not consistently influence age at conception. In the preweaning period of growth, each .1-kg increase in daily gain decreased age at conception by 10.3 days. Age at conception was negatively correlated and weight at conception positively correlated with all growth traits. The correlation between age and weight at conception was .05. This study indicates that important considerations of the producer wishing to follow a program of calving at 2 years of age in the upper mid-South on bermuda-fescue pastures are choice of breeds, mating plan and a program of supplementary feeding adequate to support growth and reproduction.

Trypanotolerance in breeds of sheep and goats with an experimental infection of Trypanosoma congolense

A study to determine the susceptibility of various breeds of small ruminants to an experimental Trypanosoma congolense infection indicated that indigenous sheep and goats showed a greater innate tolerance to the infection than exotic breeds, with exotic/indigenous cross-breeds intermediate between the two extremes. Clinical symptoms revealed a milder infection with a lower mortality in the trypanotolerant breeds in spite of a continued parasitaemia. The importance of these factors in the choice of breeds for selection programmes is discussed.