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PubMed2002

Suitability of containers from different sources as breeding sites of Aedes aegypti (L.) in a cemetery of Buenos Aires City, Argentina.

Cemeteries are ideal urban areas to study the importance of different types of containers as breeding sites of Aedes aegypti (L.). In the present study, the suitability of plastic, glass, ceramic and metal containers was evaluated in four patches within a cemetery of Buenos Aires City, Argentina. Between October 1998 and May 2000, we found 215 breeding sites of Ae. aegypti out of 13,022 water-filled containers examined. In two patches containing microenvironments sheltered from the sun, the use of the different types of containers was proportional to the offer (correlation coefficient = 0.99, P < 0.05 in both cases). In the remaining patches, plastic and metal containers were the most and less frequent breeding sites, respectively (P < 0.001 in both cases). The number of immatures per breeding site (median = 4.5) did not show significant differences among the four types of containers examined (H3, 215 = 1.216, P = 0.749). Differences found in patches from a same cemetery suggest that different microenvironmental conditions affect the suitability of each type of container for Ae. aegypti breeding. Plastic containers appeared as key breeding sites that should be removed to reduce the Ae. aegypti population in the study area.

Aedes↗
PubMed1989

Regulation of the onset of the breeding season of the ewe: importance of long days and of an endogenous reproductive rhythm.

Three experiments were conducted to evaluate the role that the increasing day lengths of late winter and spring play in timing the breeding season of the Suffolk ewe. In the first experiment, ewes were denied their normal complement of increasing day length by maintaining them on the photoperiod experienced at the winter solstice. This prevented the breeding season from occurring the subsequent autumn. In the second experiment, ewes were exposed to increases in day length at different time-intervals after the winter solstice: the normal time, later than normal or earlier than normal. Once the summer solstice photoperiod was reached, it was maintained until the end of the study. When increasing photoperiod was provided early, the breeding season was advanced; when it was provided late, reproduction was delayed. In the third experiment, ewes were exposed to a continuously increasing photoperiod matching the maximal rate of rise in natural conditions; this treatment was begun on the spring equinox and continued until mid-autumn. The steadily increasing photoperiod did not alter the time of reproductive onset in the autumn. These findings support the following conclusions for timing of the breeding season of the Suffolk ewe. (1) The lengthening photoperiod between the winter and summer solstices is required for the occurrence of the breeding season in the autumn. (2) The time of initial exposure to this lengthening photoperiod provides an important cue for determining when the reproductive period occurs. (3) The time of onset of the breeding season does not depend upon the decreasing photoperiod after the summer solstice, nor does it require the photoperiod to stop increasing as the summer solstice approaches. These findings have been incorporated into a conceptual model for temporal regulation of the annual reproductive cycle of the ewe. An important component of this model is a critical role for increasing photoperiod to initiate a process in the late winter-spring which ultimately leads to an obligatory reproductive onset in the autumn.

Animals↗
PubMed1990

Feed intake, weaning weight and net returns comparisons for four breeding systems.

Feed intake, weaning weight and direct and maternal contributions to weaning weight were estimated for four breeding systems using data collected between 1979 and 1986 from 773 cow-calf pairs at the Elora Beef Research Centre. Breeding systems included purebred Hereford (HE), small rotational dual purpose (SR) (a four-way rotational crossing system utilizing Tarentaise, Angus, Gelbvieh and Pinzgauer breeds), large rotational beef (LR) (composed of Maine-Anjou, Simmental and Charolais) and Angus-sired large rotational beef (AL) utilizing Angus as the sire breed and LR as the maternal breed. Large rotational dams had the highest feed intakes for both dry (8.9 kg DM/d) and lactation (11.5 kg DM/d) periods. Conversely, HE calves consumed the greatest amounts of creep feed (309 kg DM), followed by AL, SR and LR. The large rotational system had the highest weaning weights (265 kg) and direct (12.3 kg greater than average of observations) and maternal (9.6 kg greater than average of observations) contributions to weaning weight, followed by AL, SR and HE for all three traits. An equation was derived for net returns that included parameters for feed intake and direct and maternal weaning weight. A linear programming model was designed to incorporate this equation as the objective function and determine the breeding system(s) that maximized net returns under various production conditions. In general, LR produced the greatest net returns, followed by SR and either AL or HE, depending on specific resource constraints (limited feed supply or herd size) included in the model.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Problems and possibilities into the next decade involving beef cattle breeding research in the southern region: experiment station herds.

Opinions on expected support of animal breeding and genetics research into the next decade were requested from heads of Departments of Animal Science and directors of agricultural experiment stations in the Southern Region and from directors of agricultural experiment stations outside the Southern Region. A majority of administrators in all three groups expect a reduction in assignment of state appropriated funds for beef cattle breeding research compared with total support available. Cattle numbers and land areas assigned to breeding and genetics research may be more limited in the future. Directors of agricultural experiment stations expect animal breeding scientists to work more closely with scientists in biotechnology and to become more involved in multidisciplinary research to reduce the costs associated with maintaining large herds of cattle. Departments of Animal Science do not expect to reduce significantly the number of animal breeding positions, but they may reassign some that come open to balance departmental opportunities. Animal breeding scientists will be needed to educate graduate students, teach classes, and handle research responsibilities as in the past.

Animals↗
PubMed1991

Breed effects and heterosis in advanced generations of composite populations for growth traits in both sexes of beef cattle.

Heterosis effects for birth weight, ADG from birth to weaning, 200-d weight, ADG from weaning to 368 d, 368-d weight, 368-d height, 368-d condition score, and 368-d muscling score (males only) were evaluated separately for each sex in F1, F2, and combined F3 and F4 generations in three composite beef cattle populations. Breed effects were evaluated for the nine parental breeds (i.e., Red Poll [R], Hereford [H], Angus [A], Limousin [L], Braunvieh [B], Pinzgauer [P], Gelbvieh [G], Simmental [S], and Charolais [C]) that contributed to the three composite populations (MARC I = 1/4 C, 1/4 B, 1/4 L, 1/8 H, 1/8 A; MARC II = 1/4 G, 1/4 S, 1/4 H, 1/4 A; and MARC III = 1/4 R, 1/4 P, 1/4 H, 1/4 A). Breed effects were significant for all traits evaluated. The large differences among breeds for growth and size traits in combined additive direct and additive maternal genetic effects (Gi + Gm) provide an opportunity to use genetic differences among breeds to achieve and maintain optimum additive genetic (breed) composition for growth and size traits to match cattle genetic resources to a wide range of production and marketing situations. Combined individual and maternal heterosis was significant in the F1, F2, and combined F3 and F4 generations for each composite population and for the mean of the three composite populations in both sexes for most of the traits evaluated. In both sexes, heterosis retained in combined F3 and F4 generations was greater (P less than .05) than expected based on retained heterozygosity for birth weight, ADG from weaning to 368 d, and for 368-d weight and did not differ (P greater than .05) from expectation for other traits. These results support the hypothesis that heterosis in cattle for traits related to growth and size is due to dominance effects of genes.

Analysis of Variance↗
PubMed1991

Breed effects and heterosis in advanced generations of composite populations for birth weight, birth date, dystocia, and survival as traits of dam in beef cattle.

Heterosis effects were evaluated as traits of the dam in F2 progeny of F1 dams and F3 and 4 progeny of F2 and 3 dams in three composite populations of beef cattle. Traits included birth weight, birth date, calving difficulty percentage, and survival percentage at birth, 72 h, and weaning for calves with dams of different age classes. Breed effects were evaluated for the nine parental breeds (Red Poll [R], Hereford [H], Angus [A], Limousin [L], Braunvieh [B], Pinzgauer [P], Gelbvieh [G], Simmental [S], and Charolais [C]) that contributed to the three composite populations (MARC I = 1/4 C, 1/4 B, 1/4 L, 1/4 H, 1/8 A; MARC II = 1/4 G, 1/4 S, 1/4 H, 1/4 A; and MARC III = 1/4 R, 1/4 P, 1/4 H, 1/4 A). Among calves with 2-yr-old dams, breed effects were significant for birth weight, birth date, calving difficulty percentage, and survival percentage at birth but not at 72 h and weaning. Calf survival at weaning was lowest for smallest (less than mu - 1.5 sigma) and largest (greater than mu + 1.5 sigma) birth weight classes and did not differ among intermediate birth weight classes. Calves with difficult births with 2-yr-old dams were significantly heavier at birth (39.6 vs 35.4 kg) and had significantly lower survival at 72 h (87.1 vs 92.2%) and at weaning (77.4 vs 85.1%) than calves with 2-yr-old dams that did not experience difficult births. Among calves with dams greater than or equal to 3 yr old and from dams of all ages, breed group effects generally were significant for the traits analyzed. Important breed group effects on dystocia and survival traits were observed independent of breed group effects on birth weight. Effects of heterosis were significant for birth weight for each generation of each composite population and for the mean of the three composite populations. Generally, heterosis effects for calving difficulty percentage were not significant. Effects of heterosis generally were significant for date of birth (earlier) for each composite population and for the mean of the three composite populations. Heterosis effects on survival to weaning percentage generally were positive but generally were not significant. Heterosis retained for birth weight, birth date, and survival percentage in combined F3 and 4 generation progeny of combined F2 and 3 generation dams did not differ (P greater than .05) from expectation based on retained heterozygosity. These results support the hypothesis that heterosis in cattle for these traits is the result of dominance effects of genes.

Analysis of Variance↗
PubMed1992

Evaluation of mating systems involving five breeds for integrated beef production systems: I. Cow-calf segment.

Deterministic computer models were used to simulate the cow-calf segment of an integrated production system. Angus, Charolais, Hereford, Limousin, and Simmental breeds were included in three mating systems: pure-breeding (PB) or two- (2R) or three-breed (3R) rotational crossbreeding. Breed data were taken from the literature. Herds were evaluated over the production year. Sires represented breed averages and were available from sources outside their herds, and 100 replacement heifers were saved annually. Females in 3R had the highest average energy requirements (8,144 Mcal of ME.cow-1.yr-1) and production costs ($322.31.cow-1.yr-1), and PB females had the lowest average requirements (7,748 Mcal of ME.cow-1.yr-1) and costs ($313.2.cow-1.yr-1). Purebred systems were the least biologically and economically efficient (64.9 Mcal of ME/kg of steer equivalent, $2.35/kg of steer equivalent), respectively, and 3R systems were the most efficient (56.6 Mcal of ME/kg of steer equivalent, $1.95/kg of steer equivalent). On average, 3R systems were more efficient biologically and economically than 2R systems. However, some 2R systems were as efficient as some 3R systems. Crossbred combinations containing Angus and(or) Hereford ranked more biologically and economically efficient than other breed combinations. Conversely, British purebreds ranked more biologically efficient, whereas Continental purebreds ranked more economically efficient.

Animal Husbandry↗
PubMed1992

Lactation characteristics of nine breeds of cattle fed various quantities of dietary energy.

Milk yield data were collected by weigh-suckle-weigh procedures at approximately 14, 28, 56, 84, 112, 138, 156, 184, and 212 d postpartum for mature Angus, Braunvieh, Charolais, Gelbvieh, Hereford, Limousin, Red Poll, Pinzgauer, and Simmental cows over a 4-yr period. Individual cows were fed at one of four energy intake levels. Parameters characterizing lactation curves for 431 lactations from 179 cows were estimated by nonlinear regression. Differences due to breed, level of energy intake, and the two-factor interaction between breed and level of ME allowance for scale and shape parameters of lactation curves and derived estimates for time of peak lactation, yield at time of peak lactation, and for total yield for a 210-d lactation period were evaluated. Breed and energy intake level were significant sources of variation for all traits. Pooled over energy levels, daily yields at time of peak lactation of Braunvieh, Gelbvieh, and Pinzgauer were greater (P less than .05) than those of Angus, Charolais, Hereford, and Limousin. Simmental and Red Poll were intermediate. Total lactation yield of the Braunvieh exceeded (P less than .05) that of all other breeds with the exception of Gelbvieh. Hereford produced less milk than (P less than .05) the other breeds. The response in yields at time of peak lactation as energy allowances increased for Braunvieh, Charolis, Gelbvieh, Limousin, and Pinzgauer cows were linear and resulted in higher yields at this time. Linear increases in total 210-d yield and times of peak lactation were observed for all breeds with the exception of Hereford.

Analysis of Variance↗
PubMed1992

Effects of breed and retained heterosis on milk yield and 200-day weight in advanced generations of composite populations of beef cattle.

Retained heterosis in F2 cows nursing F3 progeny was evaluated in 3-, 4-, and greater than or equal to 5-yr-old cows. Traits evaluated included milk yield at three stages of lactation and 200-d weight of progeny. Breed effects were evaluated in the nine parental breeds (Red Poll [R], Hereford [H], Angus [A], Limousin [L], Braunvieh [B], Pinzgauer [P], Gelbvieh [G], Simmental [S], and Charolais [C]) that contributed to the three composite populations (MARC I = 1/4 B, 1/4 C, 1/4 L, 1/8 H, 1/8 A; MARC II = 1/4 G, 1/4 S, 1/4 H, 1/4 A; and MARC III = 1/4 R, 1/4 P, 1/4 H, 1/4 A). Breed effects were significant for 12-h milk yield, estimated 200-d milk yield, and 200-d weight of progeny. Herefords were lowest (P less than .05) for 12-h milk yield and estimated 200-d milk yield, and Braunvieh produced significantly more milk than all breed groups except Pinzgauer and Simmental, for which the difference approached significance. The correlation among breed group means (nine parental breeds and three composites) for 12-h milk yield with 200-d weight of progeny was .91. When 200-d weight was adjusted to a common estimated 200-d milk yield, Hereford, Angus, Red Poll, and Limousin did not differ (P greater than .05); all were significantly lighter than Braunvieh, Pinzgauer, Gelbvieh, Simmental, and Charolais, which did not differ (P greater than .05) from each other.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1993

Potential shortcomings of output:input ratios as indicators of economic efficiency in commercial beef breed evaluations.

In recent years animal breeders have increasingly made use of output:input ratios and simple measures of economic efficiency, such as annual profits, as a basis for comparisons and evaluations of the commercial applicability of alternative beef breeds. In many instances, however, output:input ratios may produce fallacious indications of economic efficiency that may, in turn, lead to erroneous conclusions regarding the true commercial applicability of the breeds evaluated. Errors potentially arising from the use of output:input ratios in breed evaluations may be attributed to a combination of 1) a narrow range of input use values under which most breeds are evaluated and 2) the inability of output:input ratios, including average annual profitability, to reflect consistently the economic objectives of commercial cow-calf producers. An alternative basis for breed comparison and evaluation is, therefore, developed from economic theories related to optimal investment and asset replacement. Comparison of the results obtained with this alternative to those obtained from output:input ratio evaluation, including annual profitability, indicate that potential value differences of as much as 33% may result from the use of output:input ratios as a primary basis of commercial breed evaluation.

Animals↗
PubMed1993

Evaluation of mating systems involving five breeds for integrated beef production systems: IV. Accounting for variability and genetic trends.

Computer models were used to simulate integrated cow-calf-feedlot production systems. Angus (A), Charolais (C), Hereford (H), Limousin (L), and Simmental (S) purebreds and two- and three-breed rotational crossbreds were included. Models were deterministic and based on data reported primarily from the 1970s. Variation in carcass weights were determined to predict distributions of carcass weights and values for 272- to 318-kg carcasses. Data were updated to a 1984 base by increasing birth, weaning, yearling, and mature weights to account for genetic trends within breeds. Two slaughter end points were considered: 288-kg carcass weight and low Choice grade. At low Choice grade, accounting for variation in carcass weights around the 272- to 318-kg target weight increased the estimated efficiency of A and AH crosses (input costs/carcass value), whereas at the 288-kg end point, efficiency rankings among other breed combinations were relatively unchanged. Including genetic trends resulted in increased estimated efficiencies among breed combinations with previously underweight carcasses at low Choice (A and AH), measured either as input costs/carcass weight or lean weight values. Within breeds, accounting for genetic trends and variation for weights caused breeds to be ranked differently when evaluated at low Choice.

Animals↗
PubMed1994

Responses of bovine lymphocytes to heat shock as modified by breed and antioxidant status.

We tested whether resistance of lymphocytes to heat stress is modified by breed, intracellular glutathione content, and extracellular antioxidants. In the first experiment, lymphocytes from Angus (Bos taurus, non-heat-tolerant), Brahman (B. indicus, heat-tolerant), and Senepol (B. taurus, heat-tolerant) heifers (12 heifers per breed) were cultured at 45 degrees C for 3 h to evaluate thermal killing, at 42 degrees C for 12 h in a 60-h phytohemagglutinin-induced proliferation test, and at 42 degrees C for 1 h to measure induction of heat shock protein 70 (HSP70). Killing at 45 degrees C was affected by breed x temperature (P < .01); the decrease in viability caused by a temperature of 45 degrees C was greater for Angus than for Brahman or Senepol. For phytohemagglutinin-stimulated lymphocytes, heating to 42 degrees C reduced [3H]thymidine incorporation equally for all breeds. Viability at the end of culture was affected (P < .001) by a breed x temperature interaction because the decrease in viability caused by culture at 42 degrees C was greatest for lymphocytes from Angus heifers. Heat shock for 1 h at 42 degrees C caused a two- to threefold increase in intracellular concentrations of HSP70, but there was no interaction of temperature with breed. In another experiment (with lymphocytes harvested from three Holstein cows), buthionine sulfoximine, a glutathione synthesis inhibitor, inhibited (P < .01) proliferation of phytohemagglutinin-stimulated lymphocytes at 38.5 and 42 degrees C. Addition of the antioxidants glutathione or thioredoxin to culture did not reduce the effects of heating to 42 degrees C on proliferation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Effect of breed, intake, and carcass composition on the status of several macro and trace minerals of adult beef cattle.

The objective was to determine the association between breed, intake, and carcass composition and the status of liver Cu, Zn, and Fe, and serum Cu, Zn, Ca, and Mg of 118 mature cows representing nine breeds of cattle. Breeds used were Angus, Braunvieh, Charolais, Gelbvieh, Hereford, Limousin, Red Poll, Pinzgauer, and Simmental. The cows were fed one of four levels of DMI: 58, 76, 93, and 111 g of DMI.wt-75.d-1. A ground alfalfa, corn, and corn silage diet was fed for up to 5 yr. There was no relationship between liver and serum concentrations of Cu, a negative correlation (P < .05) existed between liver and serum concentrations of Zn and a positive correlation (P < .01) existed between liver concentrations of Cu and Zn. Concentrations of serum Ca were positively correlated (Cu and Zn, P < .01; Mg, P < .05) with serum concentrations of Cu, Zn, and Mg, but negatively correlated (P < .01) with liver Fe. Liver Cu was higher (P < .05) for the Limousin breed than all others, except Angus. Liver Zn concentrations were higher (P < .05) for Limousin than for Pinzgauer, but no other breed differences were observed. Liver Cu concentration was not affected by daily intake, but liver Zn concentration increased (P < .05) with increased daily intake. Liver Fe concentration decreased (P < .01) in a curvilinear manner with increased daily intake. No breed differences in serum concentrations of Cu or Zn were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1997

Changes in proportions of empty body depots and constituents for nine breeds of cattle under various feed availabilities.

Mature cows (146) representing Angus, Braunvieh, Charolais, Gelbvieh, Hereford, Limousin, Pinzgauer, Red Poll, and Simmental breeds were slaughtered to contribute to the investigation of the effect of various feed availabilities on body composition. Weights recorded when cows were placed on feed were used to set daily diets at four rates of intake within each breed (55, 76, 96, and 111 g DM/[kg wt.75.d]). Cows remained on their assigned daily feed allotment throughout the study (3 to 5 yr). On the day of slaughter, shrunk live weights were recorded. Chemical determinations of protein (nitrogen x 6.25), ether extractable lipid, ash of dry matter, and moisture for hide and offal were obtained for all cows. Chemical determinations of these same constituents were obtained for the carcass soft tissue of 98 cows. Relationships among estimator traits carcass ash, warm carcass weight, resistive impedance, and carcass water from the 97 carcasses were used to predict the carcass constituents for the remaining 49 cows. Within breed, relationships between proportions of fat and empty body (sum of fat, ash, water, and protein from the three body pools of hide, offal, and carcass) were used to estimate empty body weight at 251 g fat/kg (standard reference body weight) for each of the nine breeds. Proportions of offal, carcass, hide, chemical constituents, and selected abdominal and thoracic organs relative to empty body weight from cows that attained weight stasis were regressed on one minus the ratio of individual actual empty body weight to breed standard reference weight. Among mature cows attaining weight stasis at various feeding rates, the proportion of offal remained constant, proportions of fat in carcass, hide, and offal increased with increasing feed level, and proportions of water and protein decreased. Significant variation (P < .01) attributable to breed in proportions of carcass, offal, hide, chemical constituents of the hide and offal, water, and protein of the carcass and selected organs was observed.

Abdomen↗
PubMed1998

Comparison of sire breed solutions for growth traits adjusted by mean expected progeny differences to a 1993 base.

Records on growth traits were obtained from five Midwestern agricultural experiment stations as part of a beef cattle crossbreeding project (NC-196). Records on birth weight (BWT, n =3,490), weaning weight (WWT, n = 3,237), and yearling weight (YWT, n = 1,372) were analyzed within locations and pooled across locations to obtain estimates of breed of sire differences. Solutions for breed of sire differences were adjusted to the common base year of 1993. Then, factors to use with within-breed expected progeny differences (EPD) to obtain across-breed EPD were calculated. These factors were compared with factors obtained from similar analyses of records from the U. S. Meat Animal Research Center (MARC). Progeny of Brahman sires mated to Bos taurus cows were heaviest at birth and among the lightest at weaning. Simmental and Gelbvieh sires produced the heaviest progeny at weaning. Estimates of heritability pooled across locations were .34, .19, and .07 for BWT, WWT, and YWT, respectively. Regression coefficients of progeny performance on EPD of sire were 1.25+/-.09, .98+/-.13, and .62+/-.18 for BWT, WWT, and YWT, respectively. Rankings of breeds of sire generally did not change when adjusted for sire sampling. Rankings were generally similar to those previously reported for MARC data, except for Limousin and Charolais sires, which ranked lower for BWT and WWT at NC-196 locations than at MARC. Adjustment factors used to obtain across-breed EPD were largest for Brahman for BWT and for Gelbvieh for WWT. The data for YWT allow only comparison of Angus with Simmental and of Gelbvieh with Limousin.

Animals↗
PubMed2005

Multiple-breed genetic inference using heavy-tailed structural models for heterogeneous residual variances.

Multiple-breed genetic models recently have been demonstrated to account for the heterogenous genetic variances that exist between different beef cattle breed groups. We extend these models to allow for residual heteroskedasticity (heterogeneous residual variances), specified as a function of fixed effects (e.g., sex, breed proportion, breed group heterozygosity) and random effects such as contemporary groups (CG). We additionally specify the residual distributions to be either Gaussian or based on heavier-tailed alternatives such as the Student's t or Slash densities. For each of these three residual densities using either homoskedastic (homogeneous variance) or heteroskedastic error specifications, we analyzed 22,717 postweaning gain records from a Nelore-Hereford population based on a Markov chain Monte Carlo animal model implementation. The heteroskedastic Student's t error model (with estimated df = 7.33 +/- 0.48) was clearly the best-fitting model based on a pseudo-Bayes factor criterion. Breed group heterozygosity and, to a lesser extent, calf sex seemed to be marginally important sources of residual heteroskedasticity. Specifically, the residual variance in F1 animals was estimated to be 0.70 +/- 0.16 times that for purebreds, whereas the male residual variance was estimated to be 1.13 +/- 0.09 times that for females. The CG effects were important random sources of residual heteroskedasticity (i.e., the coefficient of variation of CG-specific residual variances was estimated to be 0.72 +/- 0.06). Purebred Nelores were estimated to have a larger genetic variance (124.84 +/- 21.75 kg2) compared with Herefords (40.89 +/- 6.70 kg2) under the heteroskedastic Student's t error model; however, the converse was observed from results based on a homoskedastic Student's t error model (46.24 +/- 10.90 kg2 and 60.11 +/- 8.54 kg2, respectively). These results indicate that allowing for robustness to outliers and accounting for heteroskedasticity of residual variances has potentially important implications for variance component and genetic parameter estimates from data on multiple-breed populations.

Animals↗
PubMed2005

Breed and age affect baseline immune traits, cortisol, and performance in growing pigs.

It was hypothesized in these studies that differences would exist in baseline immune and performance measures among different breeds of pigs, and that these differences would be affected by age of the pig. Baseline immune, plasma cortisol (CORT) concentrations, and performance measures were determined among Berkshire (n = 36), Duroc (n = 18), Meishan (n = 54), Landrace x Yorkshire (White X; n = 36), and Yorkshire (n = 36) pigs at 4, 8, and 12 wk of age. All piglets were weaned at 17 to 21 d of age and moved to a common nursery environment. Total white blood cell (WBC), leukocyte differential, plasma CORT, immunoglobulin G (IgG) concentrations, natural killer cytotoxicity, neutrophil phagocytosis (PHAGO), and chemotaxis (CHTX) were evaluated. At all ages, plasma CORT was greatest in Meishan pigs, and least in Yorkshires (P < 0.05). Plasma IgG increased with age for all breeds (age: P < 0.01; breed x age: P < 0.005), except that in Meishans, IgG decreased. Natural killer cytotoxicity was greatest (P < 0.05) among Meishan pigs. There were breed x age interactions for neutrophil PHAGO (P < 0.001) and CHTX (P < 0.001). Overall, Yorkshire pigs showed the greatest (P < 0.05) percentage of PHAGO but the least (P < 0.05) CHTX. White X pigs had the greatest (P < 0.05) CHTX response. Berkshire pigs had the greatest (P < 0.001) numbers of neutrophils. At 12 wk of age, Meishan pigs had the least BW gain (P < 0.001), and Durocs had the greatest G:F (P < 0.001). There were no significant sex differences for immune (P > or = 0.15), performance (P > or = 0.20), or CORT (P = 0.70) measures. Pig breed and age influenced both baseline immune measures and plasma CORT in growing pigs, suggesting that pig breed and age are important factors influencing the response to various stressors or infectious challenges.

Age Factors↗
PubMed2006

Comparison of prenatal muscle tissue expression profiles of two pig breeds differing in muscle characteristics.

The objective of this study was to compare purebred Duroc and Pietrain prenatal muscle tissue transcriptome expression levels at different stages of prenatal development to gain insight into the differences in muscle tissue development in these pig breeds. Commercial western pig breeds have been selected for muscle growth for the past 2 decades. Pig breeds differ for their muscle phenotypes (i.e., myofiber numbers and myofiber types). Duroc and Pietrain pig breeds are extremes; Duroc pigs have redder muscle fiber types with more intramuscular fat, and Pietrain pigs have faster-growing and whiter muscle fiber types. Pietrain pigs are more muscular than Duroc pigs, whereas Duroc pigs are fatter than Pietrain pigs. The genomic background underlying these breed-specific differences is poorly known. Myogenesis is a complex exclusive prenatal process involving proliferation and differentiation (i.e., fusion) of precursor cells called myoblasts. We investigated the difference in the prenatal muscle-specific transcriptome profiles of Duroc and Pietrain pigs using microarray technology. The microarray contained more than 500 genes affecting myogenesis, energy metabolism, muscle structural genes, and other genes from a porcine muscle cDNA library. The results indicated that the expression of the myogenesis-related genes was greater in early Duroc embryos than in early Pietrain embryos (14 to 49 d of gestation), whereas the opposite was found in late embryos (63 to 91 d of gestation). These findings suggest that the myogenesis process is more intense in early Duroc embryos than in Pietrain embryos but that myogenesis is more intense in late Pietrain fetuses than in Duroc fetuses. Transcriptomes of muscle structural genes followed that pattern. The energy metabolism genes were expressed at a higher level in prenatal Pietrain pigs than in prenatal Duroc pigs, except for d 35, when the opposite situation was found. Fatty acid metabolism genes were expressed at a higher level in early (14 to 49 d of gestation) Duroc embryos than in Pietrain embryos. Better understanding of the genomic regulation of tissue formation leads to improved knowledge of the genome under selection and may lead to directed breed-specific changes in the future.

Animals↗