Terminal Sire Research Articles

Genetic parameters for a maternal breeding goal in beef production1

New maternal breeding values have been developed for use in UK beef evaluations. To undertake multitrait BLUP evaluations, it is necessary to have a full covariance matrix. This study outlines the approach taken to construct the full covariance matrices for the four beef breeds that most widely contribute to suckler beef cows in the United Kingdom. The maternal traits investigated were age at first calving, calving interval, lifespan, mature cow weight, 200-d weight, and calving difficulty. Three terminal sire traits (weight at 400 d, ultrasonic fat depth, and muscle score) were included to estimate covariances between the new and existing traits. A sire-maternal-grandsire model was used for the estimation procedure in a series of bivariate and multivariate models. A weighted bending procedure was employed to construct positive definite covariance matrices. Parameter estimates broadly agreed with literature values, although for some traits, literature information was very scarce. Some differences between parameters for different breeds were evident.

Pig sire type and sex effects on carcass traits, meat quality and physicochemical and sensory characteristics of Serrano dry‐cured ham

AbstractThis study demonstrates that improvements in animal line selection by breeding enterprises exert a strong effect on carcass traits, meat quality and sensory characteristics of Serrano dry‐cured ham. A total of 461 pigs from the offspring of a Duroc (DU) × Landrace (LD) sow mated with two DU boars and a DU × Large White (LW) boar from three breeding enterprises were evaluated. The two DU terminal sires were significantly different (P < 0.05) in carcass conformation, backfat thickness, ham and loin yields, raw ham traits, myoglobin concentration and total pigments formed during the curing process; in addition, the two lines provided different percentages of hams (54 vs 91%) with sufficient subcutaneous fat and weight to manufacture dry‐cured Serrano hams using a slow ripening process (11 months). The DU × LW sire had the best carcass and ham traits from an economic standpoint and obtained highest scores for sensory characteristics of Serrano ham evaluated by a trained panel test; furthermore, this line provided 84% of total hams suitable for manufacturing Serrano hams by a slow process. When the sex effect was analysed, carcass and ham traits of females were more favourable, but females presented a higher incidence of pale, soft and exudative (PSE) meat and a lower percentage of hams with sufficient subcutaneous fat and weight to produce Serrano hams using a slow ripening process (61% for females and 91% for castrates). On the other hand, castrates provided Serrano hams cured by a slow procedure with better organoleptic characteristics than females. Right and left hams were similar. Copyright © 2005 Society of Chemical Industry

Productivité numérique et pondérale des brebis produites du croisement entre la D’man et la race locale Queue fine de l’Ouest

La productivité des brebis F1 issues du croisement entre la race prolifique D’man et la race locale Queue fine de l’Ouest (D’man x QFO) accouplées en croisement terminal avec des béliers de race Brune noire de Suisse (BNS) a été quantifiée et comparée à celle (i) des brebis QFO et D’man respectivement conduites en race pure en station de recherche à l’Ecole supérieure d’agriculture du Kef (Esak) et (ii) des brebis QFO conduites également en race pure mais en conditions de production (El-Mabrouka). A l’Esak, les données relatives à 343, 168 et 323 agnelages respectivement des brebis de race QFO, D’man et femelles croisées D’man x QFO, collectées entre 1995 et 2003, ont été utilisées. A la naissance, la taille de la portée moyenne a été de 1,17 ± 0,37, 1,76 ± 0,71 et 1,40 ± 0,55 respectivement pour les brebis QFO, D’man et D’man x QFO alors qu’à 90 jours après la mise bas, ces performances ont été de 1,13 ± 0,40, 1,65 ± 0,70 et 1,31 ± 0,54. L’année de mise bas, le génotype de la brebis ainsi que leur interaction ont été des sources de variation significatives des tailles de la portée. A 10 jours après l’agnelage, la productivité pondérale des brebis de race QFO a été de 7,3 ± 2,5 kg et significativement plus élevée (p < 0,05) que celle des brebis D’man (6,6 ± 2,7 kg) et D’man x QFO (7,0 ± 2,3 kg). Cette tendance s’est inversée à 90 jours après l’agnelage pour les brebis D’man x QFO et D’man avec respectivement 22,9 ± 7,7 et 22,5 ± 12,0 kg, et 19,5 ± 6,7 kg pour les brebis QFO. Excepté l’âge de la brebis, les autres sources de variation ont affecté de manière très significative (p < 0,001) les mesures de productivité pondérale. A El-Mabrouka, les 1 048 et 529 agnelages relatifs respectivement aux brebis de race QFO et croisées D’man x QFO pour les années 1999, 2000 et 2001 ont été utilisés. L’année, le génotype de la brebis ainsi que son âge ont été des sources de variation très significatives (p < 0,001) de la taille de la portée à la naissance. Les femelles croisées ont produit en moyenne par portée 0,2 agneau de plus que les brebis de race QFO (p < 0,05). L’écart de productivité pondérale à 70 jours a été de l’ordre de 3 kg par brebis en faveur des brebis D’man x QFO. Les facteurs retenus ont généralement été des sources de variation significatives (p < 0,05) pour toutes les mesures de productivité pondérale. Les progrès réalisés dans la productivité ne justifient peut-être pas la mise en place d’un schéma de croisement qui exige beaucoup de rigueur et dont la gestion est laborieuse.

National Pork Producers Council Maternal Line Genetic Evaluation: A comparison of growth and carcass traits in terminal progeny1

The objective of this study was to compare growth and carcass traits of 1,252 progeny of six commercially available dam lines included in the National Pork Producers Council Maternal Line Evaluation Project. Lines compared included one maternal line supplied by each of American Diamond Swine Genetics (ADSG), Danbred NA (DB), two lines supplied by Monsanto Choice Genetics (DK and GPK347), Newsham Hybrids (NH), and Landrace x Large White females supplied by the National Swine Registry (NSR). All females were mated to DB, Duroc-Hampshire terminal sires. Traits analyzed were ADG from 56 to 115 kg live weight, days to 115 kg, backfat thickness measured at the 10th rib, carcass length, dressing percent, and 10th-rib LM area. Carcass traits were adjusted to a carcass weight of 85 kg. The statistical model included fixed effects of maternal line, sex, farrowing group, and finishing unit (farm). All two-way interactions among main effects were tested and removed from final models because they were not significant. In addition, because they were not significant, effects of farm and farrowing group were removed from models for carcass length and 10th-rib backfat thickness, and farm was removed from the model for LM area. Least squares means for ADG ranged from 0.74 to 0.79 kg/d. The GPK347 line had lower ADG and greater days to 115 kg than all other lines (P < 0.05). The ADSG (P < 0.05) and NH (P < 0.01) progeny had lower ADG than DK progeny. The DK line had the fewest days to 115 kg (P < 0.05). Progeny for the DB and NH lines had the least 10th-rib backfat, differing from ADSG, DK, and GPK347 (P < 0.05). Pigs from DB females had the greatest dressing percent, differing from ADSG, DK, GPK347, and NH (P < 0.05). The GPK347 had a lower dressing percent than all other lines (P < 0.05). Progeny of DB females had the greatest LM area, differing from ADSG, DK, GPK347, and NSR (P < 0.05). Offspring from ADSG and GPK347 had the smallest LM area; however, GPK347 and NSR did not differ. Differences in carcass length were statistically significant; however, actual differences were small. Economic weights for these traits relative to reproductive traits must be considered in integrated economic analyses to properly compare differences among lines in net economic value for specific markets.

Impact of genetic selection on management of boar replacement

Boars in an artificial insemination centre have been selected for their superior genetic potential, with ‘superior’ being defined as having traits the customer wants transmitted to his herd. The ability to meet the customers’ needs depends on the heritability of the trait, the geneticist's success in devising a selection scheme for the trait in balance with other economically important traits, and the boar's ability to produce sperm that can fertilise oocytes. Genetic evaluation research over the past 20 years has greatly increased the number of traits for which a boar can be selected: currently in the Canadian national program, these include age at 100 kg, backfat at 100 kg, feed efficiency, lean yield and litter size. In the near future, traits that are very likely to be added to this selection list include piglet survival, marbling, loin eye area and structure traits. In Canada, sires are ranked on two estimated breeding value (EBV) indices; one, focused on development of terminal sire lines, is based on the growth and yield traits and another, primarily focused on maternal line development, de-emphasises these traits and incorporates litter size. Boars that are in Canadian AI centres because of their excellent growth traits are typically in the top 5–10% of the national population for terminal sire line index, but they may be only average or substandard for litter size. Conversely, boars selected to be in the top 5–10% for conveying such reproductive traits as litter size may only be in the top 33% for growth traits. The more offspring from a superior boar in either of these indices, the faster the population average for the trait improves. The original sire gets knocked out of the elite group, is culled and replaced by a higher ranked young boar from the now improved general population. Although genetic superiority should govern an AI centre's selection and culling of boars, decision-making in real life is seldom that simple. Selection criteria may be contradictory as above, or a boar with truly superior traits may be excluded because a newly-developed molecular genetics test determines he carries an undesirable gene such as PSS, RN or others being developed. Selection for terminal sire or maternal line traits can ignore important practical factors that affect an AI centre—boars with superior genetics may not produce good semen because skeletal or penile problems prevent ejaculation, or because sperm production is poor due to a genetic flaw, disease, or some other cause. Interestingly, selection pressure for one trait may inadvertently select for a trait that is linked but whose linkage is unrecognised, and such unintentionally selected genes could benefit, harm, or have no effect on production traits. An AI centre serving a variety of customers must select boars in anticipation of their customers’ needs (including new, foreign and niche markets). A centre should also review its genetic evaluation results and progeny records, both to critique its own selection success and to try to detect unexpected linkages. Finally, an AI centre needs to predict its own future, selecting not just for production traits for the swine producer, but also for factors that enhance the centre's efficiency including boar conformation and temperament, and sperm quantity, quality and hardiness. Can we select for efficiency? Our colleagues in dairy cattle AI evaluate bull performance—should the swine industry consider evaluation of male fertility traits?

The effect of dietary ractopamine concentration and duration of feeding on growth performance, carcass characteristics, and meat quality of finishing pigs

A total of 400 barrows from Dekalb EB and 83 terminal sires mated to 43 and 45 maternal lines were used to evaluate the effects of dietary ractopamine (RAC; Paylean, Elanco Animal Health, Greenfield, IN) concentrations (0, 5, 10, or 20 ppm; as-fed basis) and feeding durations (6 to 34 d) on growth, efficiency, carcass, and meat quality characteristics of finishing pigs. Barrows were weighed and sorted into five weight blocks, each block consisting of 16 pens (five pigs per pen). Weight blocks were allocated to feeding duration treatments and assigned consecutively by weight from lightest to heaviest to represent 34, 27, 20, 13, and 6 d on test, respectively. The lightest and heaviest blocks averaged 79.8 and 103.8 kg, respectively, at the start of the test. Within a weight block, pens (four per treatment) were randomly assigned to one of four dietary concentrations of RAC in a basal diet containing 18.5% CP and 1.13% lysine. The experiment-wide target slaughter weight was 109 kg, and pigs and feeders were weighed weekly. Weight blocks (80 barrows per block) were slaughtered at a commercial packing plant after 6, 13, 20, 27, or 34 d on test. Overall, RAC supplementation improved (P < 0.05) ADG; however, ADG was not different (P > 0.08) from controls for pigs fed 5, 10, and 20 ppm RAC for 27, 34, and 6 d, respectively. During each feeding period, RAC-fed pigs had improved (P < 0.05) G:F, and, after 20, 27, and 34 d on test, pigs fed 20 ppm RAC had greater (P < 0.05) G:F compared with those fed 0 or 5 ppm RAC. Hot carcass weight was increased (P < 0.05) by RAC feeding after 13 and 27 d of feeding, and by feeding 10 and 20 ppm RAC after 20 d of feeding. After 34 d, pigs fed 20 ppm RAC had heavier (P < 0.05) hot carcass weight than pigs fed 10 ppm RAC. Fat-free lean estimates and the 10th-rib LM area were increased (P < 0.05) by feeding 10 and 20 ppm RAC after 27 d, and by feeding 20 ppm RAC after 34 d compared with controls. Japanese and American color scores, as well as L*, a*, and b* values of the LM, were not affected (P > 0.11) by 5 and 10 ppm RAC compared with controls during each feeding period. Visual marbling score for the LM was decreased (P < 0.05) when RAC was fed at 10 and 20 ppm compared with 0 ppm RAC when fed for 34 d. Dietary RAC improved growth performance at all feeding durations, whereas carcass composition was improved at longer feeding durations. In addition, 5 and 10 ppm RAC did not affect objective and subjective measures of pork quality.

Competing risks analysis of lamb mortality in a terminal sire composite population.

Mortality records from birth to weaning of 8,301 lambs from a composite population at the U.S. Meat Animal Research Center were analyzed using a competing risks model. The advantage of the competing risks model over traditional survival analyses is that different hazards of mortality can be assigned to different causes, such as disease, dystocia, and starvation. In this study, specific causes of mortality were grouped into dam-related (DAMR; e.g., dystocia and starvation), pneumonia (PNEU), disease (DIS; excluding pneumonia), and other (OTHER) categories. The hazard of mortality was analyzed using a competing risk approach, where each mortality category was assumed to be independent. Continuous- and discrete-time survival analyses were implemented using sire, animal, and maternal effects mixed models. The continuous-time survival analysis used the Weibull model to describe the hazard of mortality for each category of mortality. Under the discrete-time survival analysis, a complementary log-log link function was used to analyze animal-time data sets using weekly intervals for each category of mortality. Explanatory variables were sex, type of birth, contemporary group, and age of dam. The significant influences of type of birth and age of dam effects were consistent across category of mortality, and the sex effect was significant for all categories except the OTHER category. Estimates of variance components indicated strong maternal effects for all categories except for PNEU. Estimates of additive genetic heritabilities from the discrete maternal effects models were 0.08+/-0.04, 0.09+/-0.18, 0.16+/-0.12, 0.19+/-0.09, and 0.14+/-0.10 for OVERALL (all causes combined), DIS, DAMR, PNEU, and OTHER categories, respectively. Ignoring the cause of the defining event in mortality and longevity studies may hide important genetic differences. Therefore, the effectiveness of breeding programs relying on models that ignore multiple causes of an event in time-to-event data, such as mortality and longevity, could be affected.

Differences in slaughtering characteristics between crossbred pigs with Pietrain and Duroc as terminal sire

In this paper results on investigation of 27 carcasses of crossbred pigs were presented. The pigs were divided into two groups regarding the breed of terminal sires: Pietrain group had 15 and Duroc group 12 carcasses. All dams were double crosses of Swedish Landrace and Large White. Pigs were slaughtered at approximate weight of 100 kg and important measures of carcass and meat quality were taken. Analyses showed that pigs from Pietrain group had longer carcasses (P&lt;0.001). No differences in conformation of hams were found as well as loin eye area between the groups (P&gt;0.05), but the pigs from Pietrain group had significantly lower fat area (P&lt;0.05) indicating higher meatiness of the pigs from this group proved by significantly lower fat/meat ratio (P&lt;0.01). Although no differences in the percentage of bones were found (P&gt;0.05) carcasses of Pietrain group had significantly higher percent of lean (P&lt;0.001) and less fat (P&lt;0.01) than the carcasses of the pigs with Duroc as terminal sire breed. With exception of initial pH value measured in ham, significant differences in all meat quality indicators were found between the groups and all of these were in favour of the meat originating from pigs crosses with Duroc as terminal sire. The distribution of meat into 5 quality classes showed that in Pietrain and Duroc group, 85% and 25% (respectively) of meat samples were described as PSE (pale, soft, exudative) and RSE (reddish-pink, soft, exudative) condition. Only 15% of the samples from Pietrain group was classified as RFN (red, firm, non-exudative); in this category 58.33% of the samples from Duroc group was distributed.

Evaluation of Pilgrim, Hungarian, Chinese, Synthetic and Embden strains of geese and their crosses for body weight

The Pilgrim, Hungarian, Chinese, Selected C hinese, Synthetic (developed from Pilgrim, Chinese and Hungarian), Selected Synthetic, Large Embden and Small Embden strains of geese raised from 1980 to 1988 at the Greenbelt farm of the Centre for Food and Animal Research (formerly Animal Research Centre, and Animal Research Institute) in Ottawa, Canada varied significantly in body weight at 9 and 16 wk of age. The Large Embden strain weighed more than the Small Embden strain in 1986, and both were heavier than the Pilgrim strain (P &lt; 0.05). Significantly different body weights for the Large Embden, Small Embden and Pilgrim strains averaged over sexes were 5.03, 4.45 and 3.59 kg, respectively, at 9 wk, and 6.15, 5.49 and 4.33 kg, respectively, at 16 wk. The Pilgrim strain was similar to the Chinese and Synthetic strains in body weight, whereas the Hungarian weighed consistently less (P &lt; 0.05). Body weights for the Pilgrim, Chinese, Synthetic and Hungarian strains averaged over sexes and years 1980, 1983 and 1986 were 3.70, 3.56, 3.70 and 3.37 kg, respectively, at 9 wk, and 4.65, 4.43, 4.53 and 4.17 kg, respectively, at 16 wk. From 1982 onwards, the Chinese and Synthetic strains were selected for four generations in order to increase egg production over a 24-wk laying period and body weight at 16 wk of age, and to simultaneously decrease total fat (abdominal and intestinal). These Selected Chinese and Synthetic strains not only weighed significantly more than their corresponding Chinese and Synthetic strains maintained as randombred populations, but were also heavier than the Pilgrim strain. Corresponding body weights for Selected Chinese, Selected Synthetic, Chinese and Synthetic strains averaged over sexes and years 1983–1988 were 3.72, 3.69, 3.47 and 3.59 kg, respectively, at 9 wk, and 4.69, 4.77, 4.26 an d 4.31 kg, respectively, at 16 wk. The range in heterosis estimates for specific strain cross combinations were as follows: -6 to 8% for the Large Embden × Selected Chinese, 2 to 6% for the Selected Chinese × Selected Synthetic, -2 to 3% for the Selected Synthetic × Selected Chinese, -8 to -9% for the Large Embden × Small Embden, -1 to 1% for the Small Embden × Selected Chinese, and 4 to 8% for the Small Embden × Selected Synthetic. The variability among heterosis estimates for body weight was specific to strain crosses and subject to sampling associated with low number of sires used to produce crossbred offspring as well as the absence of reciprocal crosses. Larger studies evaluating all possible cross combinations of strains for additive and non-additive effects are warranted. Although, the Selected Chinese and Synthetic strains achieved genetic superiority for body weight, the inherent potential in the Embden strain demonstrated considerable merit for use as a terminal sire in a crossbreeding program for commercial geese production. Key words: Embden, Pilgrim; Chinese, Synthetic, Hungarian geese, crosses

Economic values for changes in carcass lean and fat weights at a fixed age for terminal sire breeds of sheep in the UK

Economic values for increases in the weights of carcass lean and fat for crossbred lambs at a fixed age, under UK commercial conditions, were estimated using a bio-economic model. Based around a biological model describing growth in lean and fat tissues over time, the model accounted for variation between lambs in rates of growth and fattening, seasonal fluctuations in market prices, feed requirements and seasonal variation in feed costs. Experimental data for female and castrated male Suffolk cross Mule lambs were used to adapt the model to represent typical commercial conditions. Lambs were sold for slaughter on reaching a chosen fatness level or when their carcass weight exceeded 21 kg. Carcass value was determined from its weight, fatness and conformation. Weekly market prices from six consecutive years were used in turn to investigate the effect of differences in prices between years. The economic values, calculated by comparing profit per animal before and after genetic increases in each trait, varied between sexes and among years. Economic values for lean weight ranged from 1.04 to 1.91£ kg −1 for females and from 1.16 to 1.93£ kg −1 for castrates. Values for fat weight ranged from −0.04 to −1.81£ kg −1 for females and from 0.69 to −2.60£ kg −1 for castrates. These values are specific to the breed-cross and production system considered. However, the model could be adapted to estimate economic values under other drafting strategies, or with appropriate data, other production systems and other breed-crosses of lambs.

Terminal sire influences lamb meat quality

Terminal sire influences lamb meat quality

Body composition influences net feed intake in terminal sire rams

Body composition influences net feed intake in terminal sire rams

Relative economic weights of maternal versus direct traits in breeding schemes

In genetic improvement schemes, the economic values of traits in the breeding objectives depend on time and frequency of realisation in offspring generations. A measure for this is the number of discounted expressions (NDE) derived by the gene flow procedure. These were calculated for two groups of traits or trait components: “Maternal traits” realised repeatedly during the life of the dam and “direct traits” realised once in early life of an animal. Selection was considered for purebred populations with a multi-purpose objective and for populations incorporated as specialised sire or dam breeds in a three-way crossbreeding scheme. The reproductive conditions of pigs, sheep, beef and dairy cattle were taken as example. For most realistic conditions in a purebred population, the marginal economic value for a maternal trait should be weighted with a factor between 0.55 and 0.60 of that for a direct trait. Much more relative weight should be given to maternal traits in dam breeds of a crossbreeding scheme, particularly in prolific species. Economic weights of maternal traits in a sire breed are generally negligible, but not when assuming a short investment period and inefficient use of terminal sires in the commercial level. If no reciprocal crosses of both types of F 1 dams are used, maternal traits are relatively more important in the breed used as maternal granddam of the terminal product than in that used in the grandsire position. These differences are higher for less prolific species.

Impacts of alternative replacement breeding systems on biological and economic performance in beef suckler production using a herd level bio-economic model

AbstractA deterministic bio-economic model was used to investigate the impact of different heifer replacement breeding systems for beef suckler cow production in different environments. It was shown that measures of cow efficiency were highly correlated with profitability in suckled calf production. However, where significant genotype differences exist in final output value due to issues of carcass quality, then more complete characterization of system profitability is recommended. In systems utilizing a terminal sire mating policy for all matings in excess of replacement heifer requirements the proportion of terminal sire matings made are affected by female fertility. Reduced cow fertility combined with late attainment of puberty in heifers and low heifer fertility has a substantial negative effect on the proportion of terminal sire matings made. This illustrates an aspect of production that can be improved by the use of crossbreeding to exploit heterosis in reproductive traits. The time frame of impacts of the different systems was seen to vary. Grading up to a pure breed allowed exploitation of heterosis in the early years of the transition leading to a boost in profitability but this boost was lost as the herd became purebred. Composite and rotational crossing systems were seen to create a steady rise in financial margin to the point where they became stable in breed proportion and heterosis. The effect of cow size was evaluated in three different environments, representing UK lowland, upland and hill. It was found that small cows became more profitable in relation to large cows as food resources became more limiting. In a non-limiting environment large cows were more profitable than small cows.

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.

Review of Canadian, Outaouais and Rideau Arcott breeds of sheep: 2. Crossbreeding, registration and subsequent release to the Canadian sheep industry

Lamb productivity of various purebreds and crossbreds were evaluated at the Centre for Food and Animal Research (formerly Animal Research Centre). Breeds included one newly developed synthetic sire and two dam strains of sheep (Arcott breeds) selected for growth and reproduction, and the Suffolk and Finnsheep. Crossbreds consisted of single crosses between the two dam strains, and three-breed cross lambs sired by either the synthetic sire strain or Suffolk breed. In a controlled environment, ewes lambed at 4-month intervals in 8-month breeding cycles while lambs were raised artificially from birth on milk replacer and high-energy diets formulated to meet nutrient requirements according to stage of production. In a semi-intensive management system, ewes lambed in 12-month breeding cycles while lambs were raised with their dams, similar to the management prevailing in a number of farm flocks across Canada. Research results demonstrated considerable promise for increased growth and reproductive performance in the newly developed synthetic strains and their crosses. Concurrently, at the University of Manitoba, one synthetic dam strain and the Suffolk breed, their crosses, and three-breed cross lambs sired by either the synthetic sire strain or the Hampshire breed were evaluated. This occurred under conditions of semi-intensive management in 8-month breeding cycles following accelerated lambing procedures widely accepted by the Canadian sheep industry where the lambs are raised with their dam. Furthermore, studies at the University of Minnesota demonstrated potential genetic merit for milking ability in the two dam strains and their crosses when these were compared to North American sheep breeds. There was agreement that sheep breeders across Canada were to be given an opportunity to benefit from the release of the Arcott breeds. In 1989, the three synthetic strains were registered as new Canadian sheep breeds (one sire strain, the Canadian Arcott, and two dam strains, the Outaouais and Rideau Arcotts) and subsequently released. Since then, these sheep have been adapting to a wide variety of management and environmental conditions in Canada to the benefit of the sheep industry. The Canadian Arcott has demonstrated genetic merit as a meat-type terminal sire breed. The Rideau Arcott, a fecund-type dam breed with superior milking ability, has been well accepted by breeders and is presently the second highest for number of sheep registered in Canada. In contrast, the Outaouais Arcott, a fecund-type dam breed, has not achieved popularity.

A comparison of halothane homozygous negative and positive pietrain sire lines in relation to carcass and meat quality, and welfare traits

Barrows ( n=164) and gilts ( n=249) from crosses of a Pietrain homozygous halothane recessive (Pi nn) and two Pietrain homozygous dominant (Pi NN-a and Pi NN-b) sire lines with Landrace×Large White NN sows, were used to study the effect of terminal sire and pre-slaughter treatment on meat quality and animal welfare. The pigs from each of the two farms where they were finished were delivered to the abattoir in two batches differing in the pre-slaughter conditions. A total of 90 pigs (54 NN and 36 Nn) were assigned to a long pre-slaughter treatment (6 h transport and 14.5 h lairage) and 89 (57 NN and 33 Nn) to a short pre-slaughter treatment (4.5 h transport and 2.5 h lairage) in Farm 1, and 118 (65 NN and 53 Nn) to the long (7 h transport and 14 h lairage) and 114 (66 NN and 48 Nn) to the short pre-slaughter treatment (1.5 h transport and 2 h lairage) in Farm 2. In Farm 1, heart rate of 3 NN and 3 Nn gilts was recorded throughout loading and transport and blood samples from 5 NN and 5 Nn were collected before loading and after transport to measure cortisol, creatine phosphokinase (CPK) and lactate dehydrogenase (LDH). Carcasses were classified and commercial cutting was carried out. At 24 h, meat quality was assessed on the Longissimus thoracis muscle by measuring electrical conductivity (PQM), colour (Minolta CR 200 and Japanese scale), pHu and drip losses. Halothane carriers showed a higher mean heart rate and higher increase in CPK levels ( P<0.05) after transport in the short pre-slaughter treatment than halothane free pigs. No effect was observed in cortisol or LDH values. Pi NN-a sired pigs had a higher live and carcass weight ( P<0.001) and loin depth ( P<0.05), but lower killing out percentage ( P<0.01) and leg yield ( P<0.01) compared with the progeny of the other two terminal sires. Gilts were leaner ( P<0.001), had a higher killing out percentage ( P<0.001) and higher yields of primal cuts ( P<0.001) compared with barrows. Pi nn sired pigs had poorer meat quality (higher PQM values in both farms, P<0.01) than Pi NN-a sired pigs. Long pre-slaughter treatment resulted in darker meat ( P<0.01) in both farms and in higher pHu ( P<0.001) in Farm 1 than short pre-slaughter treatment. Conversely, pigs subjected to the short pre-slaughter treatment showed higher PQM values ( P<0.01) in Farm 1 and higher PSE percentage ( P<0.05) in both farms compared to the ones subjected to the long pre-slaughter treatment. These results suggest that Pietrain halothane free sire lines could produce similar results on carcass quality to halothane carriers, without compromising meat quality and welfare.

Meat production using four terminal pig lines

AbstractThe influence of terminal sire (Duroc (D1 and D2), Large White/Pietrain (LW/P) and Large White (LW)) on several meat production and meat quality traits was investigated in 452 male and female offspring of Landrace/Large White dams. Age at slaughter, carcass length, carcass weight and dressing yield were similar for all lines, as was the production of shoulders, chops, and ribs with bacon. D2‐sired pigs produced more noble pieces as a percentage of their carcass weight than the other three lines. LW/P‐ and LW‐sired pigs were generally leaner than Duroc‐sired pigs. LW/P and LW pigs had the highest percentage of cuts (longissimus dorsi and semimembranosus muscle) classified as pale, soft and exudative (PSE) meat. There were no large differences between the lines in the occurrence of dark, firm and dry (DFD) cuts. Copyright © 2003 Society of Chemical Industry

Design and standards for genetic evaluation of swine seedstock populations.

The purpose of this article is to describe a program for evaluation of seedstock populations in the swine industry. Differences among seedstock populations for economically important traits must be identified in order for pork producers to efficiently use available genetic resources. National genetic evaluation programs have the potential to identify the important differences among populations and to increase the rate of genetic improvement in a population. Program results provide performance benchmarks that stimulate testing and selection procedures by seedstock suppliers that further increase the rate of genetic improvement. A Terminal Sire Line Genetic Evaluation Program was designed and conducted in the United States by the National Pork Producers Council (Des Moines, IA) to compare seedstock populations for use in crossbreeding systems. High levels of statistical accuracy for program results were established; the ability to detect differences of 0.25 SD per trait, a power of test of 75%, and a 5% significance level were selected. Pure breeds and breeding company sire lines were nominated for the program. Semen was collected from nominated boars and distributed to cooperating commercial producers during eight 1-wk breeding periods. Pigs were produced in 136 commercial herds and transported to testing facilities at 8 to 23 d of age. Nine of the 11 sire lines originally entered in the program completed the sampling requirements for statistical analysis. High levels of statistical accuracy and a large, representative sample of boars with restrictions on genetic relationships ensured that the program results included unbiased, highly accurate sire line data for growth, carcass, meat quality, and eating quality traits of economic importance. This program has shown commercial producers that they have several choices of sire lines for changing their crossbreeding programs in desired trait areas. Commercial product evaluation must be an ongoing process, and this program serves as a model for future testing and evaluation of diverse genetic seedstock populations.

Discrete time survival analysis of lamb mortality in a terminal sire composite population.

Mortality records of 8,642 lambs from a composite population at the U.S. Meat Animal Research Center during the first year of life were studied using discrete survival analyses. Lamb mortality was studied across periods from birth to weaning, birth to 365 d of age, and weaning to 365 d of age. Animal-time data sets were created for each period using different time intervals: daily, weekly, fortnightly, and monthly. Each data set was analyzed using logistic and complementary log-log sire, animal, and maternal effects models. Explanatory variables included in the models were duration of time interval, sex, type of birth, contemporary group, age of dam, and type of upbringing (nursery or not). Similar estimates of explanatory variables were obtained within the same period across models and different time intervals. Heritability estimates from the complementary log-log models were greater than those from the comparable logistic models because of the difference in variance of the respective link functions. Heritability estimates from the complementary log-log sire model ranged from 0.13 to 0.21 for all periods. These estimates were greater than the complementary log-log animal model estimates that ranged from 0.04 to 0.12. Maternal effects were important early in life, with the maternal heritability slightly greater than the direct additive heritability. Negative correlations (-0.72 to -0.65) between direct additive and maternal effects was estimated. The similarity of results among survival analysis methods demonstrates that the discrete methodology is a viable alternative to estimate variance components in livestock survival data.