Commercial Crossbreeding Research Articles

Association of single nucleotide polymorphisms in CAPN1 and CAST genes with beef tenderness from Spanish commercial feedlots

Frequencies of two SNPs in the μ-calpain (CAPN1) and calpastatin (CAST) genes in local and foreign commercial cross-breeds used in south-western Spain (Charolais, Limousin, and Retinta) were evaluated and the association of these markers with texture analysis in animals fattened under different feedlot conditions was assessed. Marker frequencies were estimated in a 286 bull crossbred population and the longisimus dorsi muscles from subsequently selected 161 animals were used to measure Warner-Bratzler shear force in raw and cooked samples at three different ageing days (1, 7, and 21). Significant differences (P ≤ 0.05) were found for shear force in raw and cooked meat samples for the three ageing days for the three crossbreeds analyzed. Significant associations were observed for raw meat for the Charolais between shear force and the CAPN1 marker (P = 0.019), as well as between the CAST polymorphism and shear force (P = 0.027) in the Limousin. No associations were found between the markers and shear force in the Retinta (P > 0.05). In contrast, although these markers might be useful in particular selected populations due to their effect on objective texture parameters, no significant association (P > 0.05) was found for cooked meat in the sample of Spanish commercial crossbreeds used in this study. Further studies with a higher number of animals will be necessary to confirm these results.    

Influence of the halothane gene (HAL) on pork quality in two commercial crossbreeds

We evaluated the effect of the halothane (HAL) gene on the quality of pork in domestic pigs. Half-carcasses from two different commercial pig (Sus domestica) crossbreeds were analyzed, 46 of which were homozygous dominant (HAL(NN)) and 69 of which were heterozygous (HAL(Nn)) for the halothane gene. The measures included backfat thickness, lean meat percentage, carcass weight, pH 24 h after slaughtering, color, and drip loss; DNA was extracted from the haunch muscle. Swine with the HAL(Nn) genotype had less backfat thickness and higher lean meat percentages than swine with the HAL(NN) genotype. Yet, swine with the HAL(Nn) genotype had lower quality meat than those with the HAL(NN) swine. The pH at 24 h was lower in HAL(Nn) swine. The meat color was paler in HAL(Nn) animals, the drip loss was greater in those animals bearing the n allele, and the amount of intramuscular fat was not related to the halothane genotype. We conclude that bearers of the recessive allele of the halothane gene produce more meat, but with quality parameters that are inferior to those sought by consumers and industry.

Marker-assisted selection for commercial crossbred performance1

Several studies have shown that selection of purebreds for increased performance of their crossbred descendants under field conditions is hampered by low genetic correlations between purebred and commercial crossbred (CC) performance. Although this can be addressed by including phenotypic data from CC relatives for selection of purebreds through combined crossbred and purebred selection (CCPS), this also increases rates of inbreeding and requires comprehensive systems for collection of phenotypic data and pedigrees at the CC level. This study shows that both these limitations can be overcome with marker-assisted selection (MAS) by using estimates of the effects of markers on CC performance. To evaluate the potential benefits of CC-MAS, a model to incorporate marker information in selection strategies was developed based on selection index theory, which allows prediction of responses and rates of inbreeding by using standard deterministic selection theory. Assuming a genetic correlation between purebred and CC performance of 0.7 for a breeding program representing a terminal sire line in pigs, CC-MAS was shown to substantially increase rates of response and reduce rates of inbreeding compared with purebred selection and CCPS, with 60 CC half sibs available for each purebred selection candidate. When the accuracy of marker-based EBV was 0.6, CC-MAS resulted in 34 and 10% greater responses in CC performance than purebred selection and CCPS. Corresponding rates of inbreeding were 1.4% per generation for CC-MAS, compared with 2.1% for purebred selection and 3.0% for CCPS. For marker-based EBV with an accuracy of 0.9, CC-MAS resulted in 75 and 43% greater responses than purebred selection and CCPS, and further reduced rates of inbreeding to 1.0% per generation. Selection on marker-based EBV derived from purebred phenotypes resulted in substantially less response in CC performance than in CC-MAS. In conclusion, effective use of MAS requires estimates of the effect on CC performance, and MAS based on such estimates enables more effective selection for CC performance without the need for extensive pedigree recording and while reducing rates of inbreeding.

Metabolitos en suero sanguíneo de cerdos alimentados con dietas suplementa-das con Cromo-L-metionina

Metabolitos en suero sanguíneo de cerdos alimentados con dietas suplementadas con Cromo-L-metionina. Un total de 48 cerdos (Sus scrofa domesticus; 24 machos castrados y 24 hembras) cruzados (Yorkshire, Hampshire, Duroc y Landrace) de 3,5 a 4,0 meses de edad y 60,0 ± 5,0 kg PV en finalización. Se alimentaron con dietas isoproteícas (14,5 % PC) e isoenergéticas (3.400 kcal EM/kg de MS), adicionadas con Cr-L-metionina (MiCroPlex®) (0, 200, 400 y 600 ppb). El experimento tuvo una duración de 45 días y se realizó de agosto a noviembre del 2002 en las instalaciones de la Universidad Autónoma Agraria Antonio Narro, localizada en Saltillo, Coahuila, México. Al tener los animales aproximadamente 95 kg PV, se tomó muestra de 15 ml de sangre por cada animal para determinar la concentración de glucosa, ácido úrico, creatinina, urea, proteinas totales y colesterol. Se aplicó un diseño completamente al azar con arreglo factorial 2 x 4; dos para el factor sexo y cuatro para nivel de cromo. Los metabolitos en suero no fueron afectados (P > 0,05) por el factor sexo. La glucosa en suero disminuyó (P < 0,05) y el colesterol incrementó (P < 0,05) con cromo en la dieta. Se concluye que el Cr incrementa el metabolismo de glucosa y disminuye el de colesterol, con lo cual puede haber energía disponible para síntesis de proteína la cual es necesaria para el crecimiento de los animales.

A descriptive study of ‘kangaroo gait’ in sheep in northern Britain

Two questionnaires were undertaken to obtain improved knowledge of the signalment, incidence and risk factors of the condition termed ‘kangaroo gait’ (KG; a forelimb locomotor disorder of adult female sheep). The first survey was mailed to 221 veterinary surgeons in practices in northern Britain which provided veterinary care for sheep, and the second was mailed to 438 sheep-flock owners and managers located in the Scottish Borders, who were recruited via their veterinary surgeons. Responses of 84.7 and 30.7% were achieved, respectively. In total, 29.7% of veterinary practices and 24.1% of flock owners and managers had identified one or more cases of KG in their practice area or flocks since the first case was reported in 1976. Almost all respondents indicated that adult females were affected—usually during lactation (and less commonly during late gestation). KG was more common among commercial crossbreeds and less common among sheep grazing hill pasture (than sheep grazing upland or lowland pasture). Cases usually occurred between March and June while sheep were at grass, although it was unclear whether the temporal pattern was associated with grazing or lambing patterns. Stocking densities were significantly higher among affected flocks than among non-affected flocks. The annual number of individuals and flocks identified as being affected had increased since the condition first was identified. Most cases of locomotor disorders resembling KG were not reported to veterinary surgeons.

Testis size after immunocastration as parameter for the absence of boar taint

Immunization against GnRH-like peptides to immunocastrate boars can be very effective in preventing boar taint and in reducing testis weight (TW) and size (TS). Experiments using vaccines with different efficacies resulted in a total of 203 male pigs with widely diverging TW and TS. The relations of the latter parameters with androstenone (AN) showed that AN levels were always lower than 0.5 μg/g (the limit for the sensory detectability of boar taint) when TW was <150 g or TS was < 9 cm. In Dutch practical circumstances, using commercial crossbreeds of pigs and a slaughterweight of ± 115 kg, AN level in backfat will be the best indicator for the presence of boar taint. A relation between low TS or low TW and low serum testosterone also existed but less strong. Skatole levels in backfat of 59 pigs were mostly low and not correlated to TS or TW. In this series of experiments growth performance and carcass quality have not been evaluated. These economically important performance parameters might have been less favorable in immunocastrates than in intact boars. However, supposedly these parameters were better than in neonatally castrated pigs, as early immunocastrates can benefit from the presence of male steroid hormones certainly until the second vaccination at 18 weeks of age. The present results show that evaluation of anti-GnRH vaccination is convenient, compared to laborious assays, and practical, as testis size can be examined visually before slaughter. Early immunocastration appears to be a good alternative to prevent the occurrence of boar taint and to abolish the distasteful practice of surgical castration of male piglets.

Ad libitum feeding of group housed Meishan synthetic sows during pregnancy

The future abolition of stall and tether systems has meant that, increasingly, producers are opting for group housing systems. Generally sows are fed a restricted concentrate ration during pregnancy at levels which do not induce satiety, leading to increased feeding motivation and competition between penmates for food. Feed competition can lead to compromised production in less dominant individuals. A possible solution would be to feed ad libituma lower energy diet which would restrict voluntary food intake (VFI) so that large undesirable weight gains would not be encountered. Brouns.(1993) found that diets containing 60% unmolassed sugar beet pulp (SBP) were capable of restricting intake to match energy requirements. Recently there has been heightened interest in the use of prolific strains of Chinese pigs such as the Meishan to develop commercial crossbreeds. Chinese breeds are reported to be capable of utilising dietary fibre to a greater extent than European breeds which would make the Meishan a more suitable option for an ad libhigh fibre feed system.

Ad libitum feeding of group housed Meishan synthetic sows during pregnancy

The future abolition of stall and tether systems has meant that, increasingly, producers are opting for group housing systems. Generally sows are fed a restricted concentrate ration during pregnancy at levels which do not induce satiety, leading to increased feeding motivation and competition between penmates for food. Feed competition can lead to compromised production in less dominant individuals. A possible solution would be to feed ad libituma lower energy diet which would restrict voluntary food intake (VFI) so that large undesirable weight gains would not be encountered. Brouns.(1993) found that diets containing 60% unmolassed sugar beet pulp (SBP) were capable of restricting intake to match energy requirements. Recently there has been heightened interest in the use of prolific strains of Chinese pigs such as the Meishan to develop commercial crossbreeds. Chinese breeds are reported to be capable of utilising dietary fibre to a greater extent than European breeds which would make the Meishan a more suitable option for an ad libhigh fibre feed system.

Commercial crossbreeding between Ile-de-France, Rambouillet, Chios and local fat-tail Awassi for market lamb production

A commercial crossbreeding experiment at the Research Farm of Çukurova University in Adana with Ile-de-France, Rambouillet, Chios and Awassi sheep is reported. The Chios breed was chosen for prolificacy and high milk production potential, the Ile-de-France for early growth and carcass quality, and the Rambouillet for early growth; the Awassi is the local sheep which is to be improved. The objective was to increase meat production by exploiting the reproductive efficiency of crossbred sheep. Firstly, Awassi ewes were mated with Chios rams, producing the F 1 generation. Secondly, the F 1 ewes were mated with Ile-de-France sires to obtain F 1 ram lambs (designated IlF 1), and F 1 ewes were also mated with Rambouillet sires to obtain F 1 ram lambs (designated RF 1). Rambouillet (Rmb) and Awassi (Aw) sheep served as the control lines. Lambing rate (lambs born per mated ewe) was 1.65, 1.16, 1.05 and 1.03 for Il × F 1, R × F 1, Aw × Aw and Rmb × Rmb matings respectively. Twelve ram lambs in the IlF 1, RF 1 and Aw groups, and eight Rmb ram lambs were used in a fattening trial. Ram lambs weighing 38–40 kg were slaughtered and the chilled carcass was divided into eight primal cuts. Average daily gains were 311.6, 253.2, 281.2 and 226.0 g for IlF 1, Aw and Rmb lambs, respectively, and feed efficiency was 3.8, 4.2, 3.7 and 5.4. Dressing percentage was higher for IlF 1 lambs than for other groups. For cold carcasses of IlF 1, RF 1 Rmb and Aw lambs, the total bone percentage was 18.8, 19.5, 19.5 and 19.7 respectively, total muscle percentage 54.9, 53.5, 54.3 and 54.1, total subcutaneous fat percentage 12.3, 14.1, 11.6 and 16.6, and total intermuscular fat percentage 10.5, 9.5, 10.1 and 6.6. Fat thickness and rib-eye areas at the 12th rib were generally largest for IlF 1 ram lambs.

Relationships between breeding values for growth of beef sires in purebreeding and crossbreeding

The studies confirmed that genetic variability for various growth traits, recorded in commercial crossbred and purebred progeny of beef sires, is slightly higher in purebred beef cattle. Breeding values were estimated according to the performance of paternal half-sib groups either purebred or commercially crossbred. Their correlation coefficients ranged from r = −0.007 to r = +0.46. The reason for these relatively low correlations may be, among other effects, due to sire × maternal breed interactions. The presence of these interactions indicates, by analogy to studies in poultry breeding, evidence of specific combining ability which should be taken into account in the selection of beef sires. The studies provide confirmatory evidence that recurrent selection of beef bulls to be used in commercial crossbreeding may be accomplished on the basis of fattening crossbred performance.

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.

Maintenance of previously cultivated land not now used for agriculture

The area of fallowed land within the EEC, which by 1985 will have increased to 5 × 10 6 ha requires, because of different circumstances, differentiated means of maintenance. Maintenance of fallowed regions by sheep is a comparatively favourable measure, but it requires a fundamental re-orientation of the sheep breeder, so that in future, not the sheep but the preservation and maintenance of the land will receive the most emphasis. An expedient engagement of sheep in the maintenance of fallowed regions depends on: • Legal pre-requisites for grazing on large areas; • Division of labour in sheep farming; • Modest landrace sheep. Commercial crossbreeding or maybe multi-breed crossing to produce marketable lambs; • Artificial rearing of lambs; • Management conditions of sheep farming in paddocks, transhumance or stationary pastoral activity; • Size of herd and areal (600 ewes without offspring can maintain 150 ha of fallowed region, which is equivalent to 4 sheep/ha); • The nutrient production of the pasture (besides roughage production for winter feeding, straw and supplementary feed containing urea can be advantageous); • Housing conditions; • Supplementary management costs (25.00–55.00 $/ha); • The difficulty of obtaining enough staff as a consequence of the relatively poor pay for people working in the sheep-keeping profession. The characters of having simple demands and being hardly make sheep the most suitable instrument for maintenance of areas which are poor in terms of feed production (below 1 000 kg starch equivalent/ha).

Experimental designs for building a synthetic dam line for meat production in sheep

A synthetic new dam line to be mated by a terminal sire line (C-line) for fat lamb production in commercial crossbreeding is to be developed by crossing a local breed (Merinolandschaf, A-line) and an exotic breed (Finnish Landrace, B-line). Therefore the following parameters must be known: • a = mean performance level by crossing dams of the home line with sires of the C-line (= control level). • d = change of performance compared to a, if B ewes are mated to C rams. • h = maternal heterosis, caused by AB cross gene combinations. The derivation of these parameters is shown in detail. Two alternative experimental designs for estimation of these parameters are discussed: method 1 requires importation of B ewes so that test results for this group are available; method 2 requires only importation of rams of the B-line. It is shown that in order to estimate the parameters with equal precision many more animals must be tested by method 2 than by method 1.