Brahman Breeding Research Articles

Influence of dietary urea level on digestive function and growth performance of cattle fed steam-flaked barley-based finishing diets.

Four Holstein steers (282 kg) with cannulas in the rumen and proximal duodenum were used in a 4 x 4 Latin square experiment to evaluate the influence of dietary urea level (0, 0.4, 0.8, and 1.2%, DM basis) in a steam-flaked barley-based finishing diet on digestive function. There were no treatment effects (P > 0.20) on ruminal digestion of OM and ADF. Increasing dietary urea level increased (linear, P < 0.01) ruminal starch digestion. Ruminal degradability of protein in the basal diet (no supplemental urea) was 60%. Increasing dietary urea level did not increase (P > 0.20) ruminal microbial protein synthesis or nonammonia N flow to the small intestine. There were no treatment effects (P > 0.20) on total-tract ADF digestion. Total tract digestion of OM (quadratic, P < 0.01) and starch (linear, P < 0.05) increased slightly with increasing urea level. Urea supplementation increased (linear, P < 0.01) ruminal pH 1 h after feeding; however, by 3 h after feeding, ruminal pH was lower (cubic, P < 0.05) with urea-supplemented diets. Urea supplementation did not affect (P > 0.20) ruminal molar proportions of acetate and propionate. One hundred twenty crossbred steers (252 kg; approximately 25% Brahman breeding) were used in an 84-d feeding trial (five pens per treatment) to evaluate treatment effects on growth performance. Daily weight gain increased (linear, P = 0.01) with increasing urea level, tending to be maximal (1.53 kg/d; quadratic, P = 0.13) at the 0.8% level of urea supplementation. Improvements in ADG were due to treatment effects (linear, P < 0.01) on DMI. Urea supplementation did not affect (P > 0.20) the NE value of the diet for maintenance and gain. Observed dietary NE values, based on growth performance, were in close agreement with expected based on tabular values for individual feed ingredients, averaging 100.4%. We conclude that with steam-flaked barely-based finishing diets, ruminal and total-tract digestion of OM and ruminal microbial protein synthesis may not be increased by urea supplementation. In contrast, ADG was optimized by dietary inclusion of 0.8% urea. Urea supplementation may not enhance the net energy value of steam-flaked barely-based finishing diets when degradable intake protein is greater than 85% of microbial protein synthesis.

Detection of quantitative trait loci for growth and beef carcass fatness traits in a cross between Bos taurus (Angus) and Bos indicus (Brahman) cattle.

This study was conducted to detect quantitative trait loci (QTL) affecting growth and beef carcass fatness traits in an experimental population of Angus and Brahman crossbreds. The three-generation mapping population was generated with 602 progeny from 29 reciprocal backcross and three F2 full-sib families, and 417 genetic markers were used to produce a sex-averaged map of the 29 autosomes spanning 2,642.5 Kosambi cM. Alternative interval-mapping approaches were applied under line-cross (LC) and random infinite alleles (RA) models to detect QTL segregating between and within breeds. A total of 35 QTL (five with genomewide significant and 30 with suggestive evidence for linkage) were found on 19 chromosomes. One QTL affecting yearling weight was found with genomewide significant evidence for linkage in the interstitial region of bovine autosome (BTA) 1, and an additional 19 QTL were detected with suggestive evidence for linkage under the LC model. Many of these QTL had a dominant (complete or overdominant) mode of gene action, and only a few of the QTL were primarily additive, which reflects the fact that heterosis for growth is known to be appreciable in crosses among Brahman and British breeds. Four QTL affecting growth were detected with genomewide significant evidence for linkage under the RA model on BTA 2 and BTA 6 for birth weight, BTA 5 for yearling weight, and BTA 23 for hot carcass weight. An additional 11 QTL were detected with suggestive evidence for linkage under the RA model. None of the QTL (except for yearling weight on BTA 5) detected under the RA model were found by the LC analyses, suggesting the segregation of alternate alleles within one or both of the parental breeds. Our results reveal the utility of implementing both the LC and RA models to detect dominant QTL and also QTL with similar allele frequency distributions within parental breeds.

Evaluation of Alternative Tactics for Management of Insecticide-Resistant Horn Flies (Diptera: Muscidae)

A 3-yr study was conducted to determine the efficacy of tactics that could be used to manage populations of insecticide-resistant horn flies, Hematobia irritans irritans (L.). Insecticide spray, spot-on or pour-on formulations and two IGRs in bolus formulation, 1.3- and 3.2-ha pasture rotations on different rotation schedules, 0–50% Brahman breeding, selected fly-resistant cows, and a mechanical trap were evaluated singly and in combination. Concentration-mortality tests indicated that horn flies collected from cows used in the current study were significantly less susceptible to diazinon, coumaphos, and methoxychlor than horn flies from cows at the same locations previously used to determine baseline susceptibility. During the 3-yr study at the Southeast Research and Extension Center (SEREC), the IGR-bolus significantly reduced (P < 0.05) horn fly numbers on both the continuous and rotational graze regimens, resulting in significantly (P < 0.05) greater calf weaning weights (average of 24 kg). Horn fly numbers were significantly greater on untreated cows during the 3-yr study at the Southwest Research and Extension Center (SWREC) compared with the mean fly numbers on cows that received fly-management treatments. All tactics and tactic-combinations used at SWREC on cattle having no Brahman breeding failed to significantly reduce insecticide-resistant horn fly numbers. However, the combination of Brahman breeding with the IGR-Bolus and mechanical trap significantly reduced horn fly numbers and resulted in significant increases in calf weaning weight. In addition, mean horn fly numbers decreased significantly as the percentage Brahman breeding increased with 50% Brahman breeding reducing horn fly numbers by 140 flies per cow. No significant difference was found between the mean fly numbers on the fly-resistant purebred group and the cows that had no Brahman breeding but received the IGR-Bolus or used the mechanical trap. The use of synergized zeta-cypermethrin pour-on treatment successfully complimented the use of IGR-bolus and mechanical traps in reducing insecticide-resistant horn fly numbers. Neither 1.3- nor 3.2-ha size paddocks and stocking rates used in the rotation graze regimens at SEREC and SWREC, respectively, significantly reduced horn fly numbers when compared with continuously grazed paddocks. Data indicated the importance of using tactics that reduce horn fly numbers to ≈150 horn flies per cow. These data demonstrated the efficacy of using tactic combinations to manage insecticide-resistant horn fly populations.

Genetic divergence in cellular resistance to heat shock in cattle: differences between breeds developed in temperate versus hot climates in responses of preimplantation embryos, reproductive tract tissues and lymphocytes to increased culture temperatures

The detrimental effects of heat stress on fertility in cattle are less pronounced in heat-tolerant breeds. Although these genetic differences reflect differences in thermoregulation, cells from heat-tolerant breeds are less adversely compromised by increased temperature (that is, heat shock) than cells from heat-sensitive breeds. Experiments were performed to test the hypothesis that cells and tissues from two thermotolerant breeds (Brahman and Senepol) are better able to survive and function after exposure to increased temperature than cells and tissues from two thermosensitive breeds (Holstein and Angus). Exposure of embryos at>eight-cell stage at day 5 after insemination to heat shock of 41.0 degrees C for 6 h decreased development to the blastocyst stage and the number of cells per embryo. However, the deleterious effect of heat shock on blastocyst formation and the number of cells per embryo was less pronounced for Brahman than for Holstein and Angus breeds. Embryos from Senepol cows had very low development and it was not possible to determine heat shock effects in this breed. In contrast to the sensitivity of embryos to heat shock, there was no effect of a 41.0 degrees C heat shock on [(3)H]leucine incorporation into proteins secreted by oviductal or endometrial explants. Lymphocytes from Brahman and Senepol cows were more resistant to heat-induced apoptosis than lymphocytes from other breeds. Heat shock reduced lymphocyte glutathione content but the magnitude of the decrease was not affected by breed. In conclusion, embryos from Brahman cows are more resistant to heat shock than embryos from Holstein or Angus cows. Genetic differences are also present in thermotolerance for apoptosis response in lymphocytes, with Brahman and Senepol cattle being more resistant to heat shock than Angus and Holstein breeds. It is likely that the evolutionary forces that led to the Brahman and Senepol breeds being adapted to hot climates resulted in the selection of genes controlling resistance to cellular heat shock.

Análise multivariada de resultados da ovulação múltipla seguida de transferência de embriões de doadoras zebuínas

Resultados de 1390 ovulações múltiplas seguidas de transferência de embriões foram submetidas à análise multivariada para estudo da relação entre algumas variáveis envolvidas no processo. As superovulações foram realizadas no período de 1989 a 1999 em várias doadoras zebuínas das raças Brahman (31), Gir (22), Guzerá (68) e Nelore (411), provenientes de 61 rebanhos de diversas regiões do Brasil. As doadoras tinham idades entre 1,5 e 19,5 anos. Analisaram-se apenas dados de primeira colheita e dados de colheitas consecutivas. As principais correlações encontradas com a análise de ambos os arquivos pelo método de Pearson foram de: 0,72 entre o total de estruturas recuperadas (ER) e o número de embriões viáveis (EV); 0,66 entre ER e o total de prenhezes positivas (PP); 0,53 entre ER e o número de corpos lúteos palpados (CL); 0,89 entre EV e PP; 0,33 entre EV e CL; e 0,30 entre PP e CL. Observou-se associação entre coeficiente de endogamia, idade das doadoras à superovulação, droga estimuladora, dose da droga estimuladora, ordem de colheita e número de inseminações. Foram estimados os seguintes fatores nas análises de colheitas consecutivas: fator 1 - que reduz a resposta à superovulação, fator 2 - que define os esquemas de superovulação de doadoras e fator 3 - que define o sucesso do esquema de superovulação. Com os dados de primeira colheita foram obtidos: fator 1 - que define a idade ótima à superovulação, fator 2 - que define os esquemas de superovulação de doadoras e fator 3 - que define esquema alternativo de superovulação. As análises indicaram que os resultados de superovulação são muito variáveis e que há grande efeito da idade da doadora à superovulação, do coeficiente de endogamia da doadora, da ordem de colheita, da dose da droga e do número de inseminações sobre esses resultados. O número de embriões viáveis por superovulação e a correlação entre número de embriões viáveis e total de prenhezes positivas podem ser indicadores da eficiência do MOET.

The efficacy of neem seed extract (&lt;i&gt;Azadirachta indica&lt;/i&gt;) to control tick infestation in Tswana, Simmentaler and Brahman cattle

The aim of this experiment was to evaluate the use of neem seed extract for controlling common cattle ticks of the Ixodidae species. Three bulls and three cows of the Tswana, Brahman and Simmentaler breeds were cleared of ticks using ether and hand-picking techniques. Each animal was then naturally infested with ticks. A 5% (w/v) water extract of neem seed kernel was applied at a rate of 5 g/kg body weight to various anatomical sites on the animals allocated to the experimental treatment, while the control treatment animals were sprayed with tap water. Treated and control animals grazed together and were mustered at weekly intervals for examination. Tick population densities on animals treated with neem seed extract were lower than on untreated animals. Indigenous Tswana cattle harboured fewer ticks during periods of tick abundance than Brahman or Simmentaler cattle. It was concluded that neem seed extract is effective in controlling ectoparasites on livestock. South African Journal of Animal Science Vol.32(1) 2002: 1-6

The assignment by linkage mapping of four genes from human chromosome 22 to bovine chromosome 5 and 17.

Polymerase chain reaction oligonucleotides were designed to amplify bovine specific sequences for four genes that are located on human chromosome 22 (HSA22): crystallin beta A4 (CRY B A4), parvalbumin (PVALB), tissue inhibitor of metalloproteinase 3 (TIMP3) and matrix metalloproteinase 11 (MMP11). Single strand conformation analysis of these bovine gene fragments defined polymorphisms within a population of three large half-sib families of three F1 Charolais x Brahman sires and a composite herd comprising an equal proportion of Africander, Brahman, Hereford and Shorthorn breeds (CSIRO pedigree). The DNA marker genotypes were used to define linkage associations to other DNA markers already placed on the CSIRO linkage map. The genes TIMP3 and PVALB were assigned to BTA5 and CRYbetaA4 and MMP11 to BTA17.

Estádios de desenvolvimento embrionário de vacas zebuínas superovuladas

O objetivo deste estudo foi relatar o estádio de desenvolvimento de embriões coletados a partir de processos superovulatórios em zebuínos. Foram utilizadas 26 vacas, 16 da raça Nelore Padrão, três da Nelore Mocho, quatro da Gir, duas da Brahman e uma da raça Guzerá. Para o processo de superovulação utilizaram-se 350 UI de FSH em oito doses decrescentes a cada 12 horas, a partir do 10ºdia do ciclo estral (estro = dia 0). Ao sétimo dia após o estro os embriões foram coletados pelo método não cirúrgico e avaliados ao microscópio estereoscópio quanto à qualidade e estádio de desenvolvimento embrionário. Foram coletados 135 embriões viáveis, sendo 68,2% (92/135) Nelore Padrão, 12,6% (17/135) Nelore Mocho, 11,1% (15/135) Gir, 5,2% (7/135) Brahman e 3,0% (4/135) Guzerá. Os embriões foram classificados segundo a qualidade em grau I, 51,1% (69/135), grau II, 43,7% (59/135), grau III, 4,4% (6/135), e grau IV, 0,7% (1/135), e segundo o estádio de desenvolvimento em mórula, 3,7% (5/135), blastocisto inicial, 16,3% (22/135), blastocisto, 37,0% (50/135), blastocisto expandido, 42,2% (57/135), e blastocisto eclodido, 0,7% (1/135). Observou-se predominância de estádios embrionários avançados (blastocisto, blastocisto expandido e blastocisto eclodido) que representaram 80% do total de embriões.

Technical note: Constrained optimization of breed composition in composite populations to balance net merit and risk.

We developed a method to derive optimum composite genotypes when the proportion of a specific breed (or combination of breeds) in the composite is constrained to a desired level. The method allows development of composites that balance net merit according to available parameters and reflects the production system and(or) risk preference, particularly when traits in the breeding objective do not represent all traits important for production. The method can also be used to evaluate the cost of constraining breed use. For example, when the true optimal composite is difficult to obtain in the time frame available to the producer, the predicted merit of the composite with breed proportion restricted to those that are obtainable in practice can be compared with the predicted merit of the true optimum composite. In a case study the method is used to optimize a tropical composite using Brahman, Charolais, and Belmont Red breeds. The proportion of Charolais is to be constrained to 50%. Using growth parameters from a tropical crossbreeding experiment, the unconstrained optimum composite was 32.5% Brahman, 11.1% Belmont Red, and 56.3% Charolais. When the proportion of Charolais in the composite was constrained to 50%, optimum proportions of Brahman and Belmont Red were 33.9% and 16.1% respectively. In the case study net merit (annualized profit per cow exposed, $), as defined by the growth parameters, was .2% less than that of the unconstrained optimum composite.

Is the American Zebu really Bos indicus?

The American continent was colonized in the 16th century by Europeans who first introduced cattle of Bos taurus origin. Accounts register introduction of Bos indicus cattle into South America in the 19th and continuing through the 20th century, and most reported imports were males derived from the Indian subcontinent. In the present study we show, by using mitochondrial DNA (mtDNA) polymorphism, major participation of matrilineages of taurus origin in the American Zebu purebred origin, i.e., 79, 73 and 100% for the Nellore, Gyr and Brahman breeds, respectively. Moreover, we have created a restriction map identifying polymorphism among B. taurus and B. indicus mtDNA using three restriction enzymes. Results are discussed concerning American Zebu origins and potential use of this information for investigating the contribution of cytoplasmic genes in cattle production traits.

Short Communication: Lack of Breed Differences in Responses of Bovine Spermatozoa to Heat Shock

An experiment was conducted to test whether the magnitude of effects of heat shock on spermatozoal function were less for thermotolerant breeds (Brahman and other breeds with Brahman influence) than for breeds that evolved in northern Europe (Angus and Holstein). Frozen spermatozoa were thawed, purified by Percoll gradient centrifugation and incubated at 38.5, 41, or 42°C for 4h. Sperm motility was then analyzed with a Hamilton Thorn Motility Analyzer. Heat shock reduced the percentage of sperm that were motile, mean track speed, and mean path velocity. There were no significant breed × temperature interactions for these traits. The mean frequency of tail beat tended to be reduced by heat shock in bulls of Brahman-influenced breeds and, to a lesser extent, in Brahman bulls, but it was not affected by heat shock in Angus or Holstein bulls. For no traits were there significant temperature × bull within breed interactions. Overall, results indicate that 1) heat shock reduces motility of bovine spermatozoa and 2) genetic effects are unlikely to be an important determinant of the function of ejaculated sperm following heat shock.

Calcium-activated tenderization of strip loin, top sirloin, and top round steaks in diverse genotypes of cattle.

Steers of known percentage Brahman (B) and Angus (A) breeding (100% A, n = 6; F1 B x A, n = 6; and 100% B, n = 6) were used to determine the effect of calcium chloride injection on the calpain proteinase system and meat tenderness. The steers were slaughtered in six replications (at either 9 or 14 mm of backfat, determined ultrasonically), with each breed type represented. Calpains and calpastatin activities were measured on fresh, prerigor longissimus muscle samples. Carcass data were collected after a 24-h chill, and the short loin (IMPS #180), top sirloin (IMPS #184), and top round (IMPS #168) were removed from both sides of each carcass. The cuts from the right side were then injected at 5% (wt/wt) with CaCl2 solution (2.2%). Longissimus muscle calpain and calpastatin activities were also measured at 48 h postmortem from the injected and control sides of each carcass. Warner-Bratzler shear force was measured on steaks from the three subprimals aged 1, 2, 5, 15, or 31 d. Marbling scores and USDA quality grades were higher (P<.05) in A than in F1 B x A and B carcasses. Calpastatin activity was higher (P<.05) in muscle from B than in muscle from A and F1 B x A steers, and postmortem storage (O vs 48 h) and CaCl2 injection reduced (P<.05) the activity of the calpains and calpastatin. Strip loin and top sirloin steaks from A and F1 B x A steers were more tender (P<.05) than steaks from B steers; however, top round steak tenderness did not differ (P>.05) across breed type. Calcium injection improved strip loin and top sirloin steak tenderness, but it did not affect top round steak tenderness. Collectively, these data show that CaC12 injection can be used to improve meat tenderness, with similar responses shown in cattle containing 0, 50, and 100% B inheritance. However, even with CaCl2 injection, B steaks are less tender than their A and F1 B x A counterparts.

Evaluation of Angus, Charolais, and Hereford as terminal sire breeds on Hereford and first-cross cows. III. Meat quality of progeny

Carcasses of 435 Angus, Charolais, and Hereford sired progeny out of straightbred Hereford (H × H), and first-cross Brahman × Hereford (B × H), Simmental × Hereford (S × H) and Friesian × Hereford (F × H) dams, were evaluated for meat quality traits. The cattle had been raised and slaughtered for the vealer (both sexes), yearling domestic (both sexes), or the heavy export steer market. Meat samples from the M. longissimus (LD, striploin) and the M. semitendinosis (ST, eyeround) were evaluated for colour, cooking loss, sarcomere length, shear force parameters, instron compression values, lipid content (LD only), cholesterol content (LD, vealers only), and taste panel assessment (LD only). The effects of sire breed and dam breed were small and were significant for only a few traits. The use of either hot carcass weight or pH of meat as a covariate reduced the differences further but did not change sire breed or dam breed rankings. Meat from B × H progeny, which had 25% Bos indicus (Brahman) breeding, was as tender as that from progeny of the other dam breeds, which had no Bos indicus breeding. Striploins from vealer carcasses were more tender and had less fat (mean peak force, 3·8 kg; mean lipid in lean steak, 3·8 g/100 g) than those from yearling domestic carcasses (mean peak force, 4·1 kg; mean lipid in lean steak, 5· 0 g/100 g) which in turn were more tender than those from heavy export steer carcasses (mean peak force, 4·9 kg; mean lipid in lean steak, 6·3 g/100 g). From the total responses of the taste panel, 65% rated vealer striploins of good or excellent overall acceptability, compared with 29% for heavy export steer meat. Trimming subcutaneous fat from striploin steaks of vealers reduced lipid content and cholesterol content by 85% and 32% to 3·8 g/100 g and 55 mg/100 g, respectively.

Interaction Between Calf Sex and Calf Genetic Type for Preweaning Traits of Calves Varying in Percentage Brahman Breeding

Two data sets were utilized to evaluate interaction between calf sex and calf genetic type for preweaning performance of calves varying in percentage (0, 50, 100) Brahman breeding. Data set I involved birth weight, preweaning average daily gain, and weaning weight records on 3562 Angus (AA), Brahman ♂ × Angus ♀ (BA) and Brahman (BB) calves; data set II consisted of birth weight, preweaning average daily gain and weaning weight records on 3752 Hereford (HH), Brahman ♂ × Hereford ♀ (BH) and Brahman (BB) calves. For both data sets, the calf sex × calf genetic type interaction was significant (P<0.01) except for preweaning average daily gain in data set II. In all cases, the significant interactions were represented by a change in magnitude rather than a change in rank for the two sexes of each calf genetic type. These results indicate that sex differences are expected to be much greater for Brahman-sired BA and BH calves than for calves of 0% (AA or HH) or 100% (BB) Brahman breeding. These increased sex differences are of greatest importance for birth weight because of the relationship that exists between birth weight and calving difficulty.

Feedlot cattle with calm temperaments have higher average daily gains than cattle with excitable temperaments.

This study was conducted to assess the effect of temperament on the average daily gains of feedlot cattle. Cattle (292 steers and 144 heifers) were transported to Colorado feedlot facilities. Breeds studied included Braford (n = 177), Simmental x Red Angus (n = 92), Red Brangus (n = 70), Simbrah (n = 65), Angus (n = 18), and Tarentaise x Angus (n = 14). Cattle were temperament rated on a numerical scale (chute score) during routine weighing and processing. Data were separated into two groups based on breed, Brahman cross (> or = 25% Brahman) and nonBrahman breeding. Animals that had Brahman breeding had a higher mean temperament rating (3.45 +/- .09) or were more excitable than animals that had no Brahman influence (1.80 +/- .10); (P < .001). These data also show that heifers have a higher mean temperament rating than steers (P < .05). Temperament scores evaluated for each breed group also showed that increased temperament score resulted in decreased average daily gains (P < .05). These data show that cattle that were quieter and calmer during handling had greater average daily gains than cattle that became agitated during routine handling.

Carcass characteristics, the calpain proteinase system, and aged tenderness of Angus and Brahman crossbred steers.

We used 69 steers of varying percentage Brahman (B) breeding (0% B, n = 11; 25% B, n = 13; 37% B, n = 10; 50% B, n = 12; 75% B, n = 12; 100% B, n = 11) to study the relationship between carcass traits, the calpain proteinase system, and aged meat tenderness in intermediate B crosses. Calpains and calpastatin activities were determined on fresh longissimus muscle samples using anion-exchange chromatography. The USDA yield and quality grade data (24 h) were collected for each carcass. Longissimus steaks were removed and aged for 5 or 14 d for determination of shear force and 5 d for sensory panel evaluation. Even though some yield grade factors were affected by the percentage of B breeding, USDA yield grades did not differ (P > .15) between breed types. Marbling score and USDA quality grade decreased linearly (P < .01) with increasing percentage of B breeding. Shear force after 5 and 14 d of aging was higher (P < .05) in the 100% B steers than in all other breed types, which were not significantly different. Sensory panel tenderness and connective tissue scores decreased linearly (P < .05) with increasing B breeding. A quadratic effect was also noted for tenderness and connective tissue scores; 37% B steers received the highest scores. A similar response was found in mu-calpain activities; the 37% B steers had the highest activities. Conversely, calpastatin activity increased linearly (P < .01) with increasing percentage B breeding. These data show strong linear relationships between calpastatin activity (positive), marbling score (negative), and percentage B breeding, suggesting a possible combined effect of these traits on aged tenderness of intermediate Brahman crosses.

Genetic parameters for growth and carcass traits from crossbreeding (1996)

Growth and carcass data from 5 years of a long-term, rotational, crossbreeding project were used to calculate heritabilities and genetic and phenotypic correlations for direct and maternal birth and weaning weight, gain on feed, hot carcass weight, ribeye area, marbling score, and age at slaughter. Angus, Brahman, Hereford, Charolais, Simmental, and Gelbvieh breeds were involved. Heritabilities of traits ranged from low (maternal weaning weight 0.04) to moderate (direct weaning weight 0.41). Direct birth weight, direct weaning weight, gain on feed, and hot carcass weight had moderate to high genetic correlations. Marbling had negative genetic correlations with birth and weaning weight but positive correlations with slaughter age and hot carcass weight.

Breed and management comparisons and genetic parameters for carcass traits (1995)

Carcass data from 5 years of a long-term, rotational , crossbreeding project were used to calculate heritabilities, genetic and phenotypic correlations , and management effects and to compare breeds for marbling, ribeye area, and hot carcass weight. Angus, Brahman, Charolais, Hereford, Polled Hereford, Gelbvieh, and Simmental breeds were involved. Sixty percent of the steer calves were fed as calves and 40% as yearlings. Heritabilities were .40 for marbling, .46 for ribeye area, and .51 for carcass weight. Genetic and phenotypic correlations were high between carcass weight and ribeye area but low between marbling and the other traits. Steers fed as calves had more marbling and lighter carcasses than steers fed as yearlings. Higher percentages of Gelbvieh or Brahman breeding resulted in lower (P<.05) marbling . Increased percentage of Charolais and Simmental breeding increased (P<.05) ribeye area and tended to increase carcass weight without reducing marbling.

Efficacy of Brahman breeding in the management of insecticide-resistant horn flies (Diptera: Muscidae) on beef cattle.

The efficacy of Brahman breeding used as an alternative tactic to manage insecticide-resistant populations of adult horn flies, Haematobia irritans irritans (L.), was determined. Concentration-mortality bioassays done at Booneville and Hope, AR, in 1988 and 1989, respectively, showed that horn fly populations were resistant to diazinon, pirimiphos methyl, tetrachlorvinphos, and methoxychlor. Data showed loss of field efficacy for coumaphos and delnav. Mean horn fly counts on Braham cows were significantly lower than on Angus cows for all sampling dates in 1989 and 1990. Mean fly counts on Brahman x Angus cows were approximately intermediate to the two purebred mean fly counts. Brahman breeding caused significant reductions in the number of organophosphate-resistant horn flies, which had been equal to or greater than that obtained from continued spraying with organophosphate insecticides. The Brahman x Hereford cows, which have one-eighth greater Brahman breeding than the Brangus cows, had fewer horn flies on 48 of 56 sampling dates in 1988-1990 and significantly fewer flies on 37 sampling dates. The effectiveness of Brahman breeding in causing lower numbers of insecticide-resistant horn flies significantly increased as the percentage of Brahman breeding increased.

Prediction of multiple genotypes in bovine embryos by PCR-RFLP analysis

Bovine leukocyte antigens (BoLA) are extensively used as markers for bovine disease and immunological traits. However, none of the BoLA genes in Southeast Asian breeds have been characterized by polymerase chain reaction (PCR)-sequence-based typing (SBT). Therefore, we sequenced exon 2 of the BoLA class II DRB3 gene from 1120 individual cows belonging to the Holstein, Sahiwal, Simbrah, Jersey, Brahman, and Philippine native breeds using PCR-SBT. Several cross-breeds were also examined. BoLA-DRB3 PCR-SBT identified 78 previously reported alleles and five novel alleles. The number of BoLA-DRB3 alleles identified in each breed from the Philippines was higher (71 in Philippine native cattle, 58 in Brahman, 46 in Holstein × Sahiwal, and 57 in Philippine native × Brahman) than that identified in breeds from other countries (e.g., 23 alleles in Japanese Black and 35 in Bolivian Yacumeño cattle). A phylogenetic tree based on the DA distance calculated from the BoLA-DRB3 allele frequency showed that Philippine native cattle from different Philippine islands are closely related, and all of them are closely similar to Philippine Brahman cattle but not to native Japanese and Latin American breeds. Furthermore, the BoLA-DRB3 allele frequency in Philippine native cattle from Luzon Island, located in the Northern Philippines was different from that in cattle from Iloilo, Bohol, and Leyte Islands, which are located in the Southern Philippines. Therefore, we conclude that Philippine native cattle can be divided into two populations, North and South areas. Moreover, a neutrality test revealed that Philippine native cattle from Leyte showed significantly greater genetic diversity, which may be maintained by balancing selection. This study shows that Asian breeds have high levels of BoLA-DRB3 polymorphism. This finding, especially the identification of five novel BoLA-DRB3 alleles, will be helpful for future SBT studies of BoLA-DRB3 alleles in East Asian cattle.