Brahman Cattle Research Articles

USE OF HYDRODYNAMIC PRESSURE PROCESSING AND BLADE TENDERIZATION TO TENDERIZE TOP ROUNDS FROM BRAHMAN CATTLE†

ABSTRACT Tenderization effects of hydrodynamic pressure processing (HDP), blade tenderization (BT) and a combination of BT followed by HDP (BT + HDP) were evaluated with 12 top rounds from Brahman cattle selected for toughness. Warner–Bratzler shear testing was performed on the day of treatment (D0) and after storage (D7). On D0, BT and HDP increased tenderness by 18% and BT + HDP yielded a 14% improvement over control steaks. Tenderness increased (P < 0.05) for HDP and BT + HDP treatment between D0 and D7, whereas tenderness did not change for BT treatment. Control samples increased (P < 0.05) in tenderness because of aging alone (20% improvement). Overall tenderness improvements for BT + HDP and HDP (D7) versus control (D0) were 37 and 29%, respectively. BT provided instant tenderization but without additional improvement during aging. HDP and BT + HDP resulted in instantaneous tenderization that also increased over time and provided the greatest amount of overall improvement in tenderness.

Glicogenose hereditária em bovinos Brahman no Brasil

Relata-se uma enfermidade hereditária em bovinos caracterizada por acúmulo lisossomal de glicogênio em diversos órgãos. A doença foi diagnosticada em um rebanho da raça Brahman, no município de Porto Lucena, Rio Grande do Sul, Brasil. Os animais afetados, a partir de 1 mês de idade, apresentavam dificuldade em acompanhar a mãe e crescimento retardado, desenvolviam fraqueza e tremores musculares, letargia e perda de condição corporal progressivos. Todos os bezerros eram descendentes do mesmo touro. Foi realizada necropsia em três bezerros doentes; palidez muscular do tronco e membros foi a única alteração macroscópica encontrada. Vacuolização citoplasmática de diversos órgãos foi a principal alteração histológica observada. Os vacúolos citoplasmáticos eram mais evidentes na musculatura esquelética, miocárdio, especialmente nas fibras de Purkinje e em neurônios do Sistema Nervoso Central (SNC). Nos tecidos mais afetados foi observada grande quantidade de grânulos ácido periódico de Schiff (PAS), positivos e negativos quando o tecido era tratado previamente com diastase. Uma mutação no gene da glicosidase alfa ácida, causadora da glicogenose generalizada em bovinos Brahman, a 1057?TA, foi detectada pela técnica de reação em cadeia de polimerase (PCR) em tecidos dos animais necropsiados. Também foi detectada a presença dessa mutação em amostras de sangue de animais parentes dos bezerros doentes. Os achados clínicos, patológicos e moleculares são semelhante ás descrições de glicogenose tipo II em bovinos da raça Brahman descritos na Austrália. Não foram encontrados relatos anteriores em revistas indexadas sobre glicogenose hereditária em bovinos Brahman no Brasil.

A new single nucleotide polymorphism in CAPN1 extends the current tenderness marker test to include cattle of Bos indicus, Bos taurus, and crossbred descent1

The three objectives of this study were to 1) test for the existence of beef tenderness markers in the CAPN1 gene segregating in Brahman cattle; 2) test existing CAPN1 tenderness markers in indicus-influenced crossbred cattle; and 3) produce a revised marker system for use in cattle of all subspecies backgrounds. Previously, two SNP in the CAPN1 gene have been described that could be used to guide selection in Bos taurus cattle (designated Markers 316 and 530), but neither marker segregates at high frequency in Brahman cattle. In this study, we examined three additional SNP in CAPN1 to determine whether variation in this gene could be associated with tenderness in a large, multisire American Brahman population. One marker (termed 4751) was associated with shear force on postmortem d 7 (P < 0.01), 14 (P = 0.015), and 21 (P < 0.001) in this population, demonstrating that genetic variation important for tenderness segregates in Bos indicus cattle at or near CAPN1. Marker 4751 also was associated with shear force (P < 0.01) in the same large, multisire population of cattle of strictly Bos taurus descent that was used to develop the previously reported SNP (referred to as the Germplasm Evaluation [GPE] Cycle 7 population), indicating the possibility that one marker could have wide applicability in cattle of all subspecies backgrounds. To test this hypothesis, Marker 4751 was tested in a third large, multisire cattle population of crossbred subspecies descent (including sire breeds of Brangus, Beefmaster, Bonsmara, Romosinuano, Hereford, and Angus referred to as the GPE Cycle 8 population). The highly significant association of Marker 4751 with shear force in this population (P < 0.001) confirms the usefulness of Marker 4751 in cattle of all subspecies backgrounds, including Bos taurus, Bos indicus, and crossbred descent. This wide applicability adds substantial value over previously released Markers 316 and 530. However, Marker 316, which had previously been shown to be associated with tenderness in the GPE Cycle 7 population, also was highly associated with shear force in the GPE Cycle 8 animals (P < 0.001). Thus, Marker 316 may continue to be useful in a variety of populations with a high percentage of Bos taurus backgrounds. An optimal marker strategy for CAPN1 in many cases will be to use both Markers 316 and 4751.

The efficacy of a vitamin D 3 metabolite for improving the myofibrillar tenderness of meat from Bos indicus cattle

The influence of a once only administration of a metabolite of vitamin D 3 (HY · D ®-25-hydroxy vitamin D 3) on myofibrillar meat tenderness in Australian Brahman cattle was studied. Ninety-six Brahman steers of three phenotypes (Indo-Brazil, US and US/European) and with two previous hormonal growth promotant (HGP) histories (implanted or not implanted with Compudose ®) were fed a standard feedlot ration for 70 d. Treatment groups of 24 steers were offered daily 10 g/head HY · D ® (125 mg 25-hydroxyvitamin D 3) for 6, 4, or 2 d before slaughter. One other group of 24 steers was given the basal diet without HY · D ®. Feed lot performance, blood and muscle samples and carcass quality data were collected at slaughter. Calcium, magnesium, potassium, sodium, iron and Vitamin D 3 metabolites were measured in plasma and longissimus dorsi muscle. Warner–Bratzler (WB) shear force (peak force, initial yield) and other objective meat quality measurements were made on the longissimus dorsi muscle of each steer after ageing for 1, 7 and 14 d post-mortem at 0–2 °C. There were no significant effects of HY · D ® supplements on average daily gain (ADG, 1.28–1.45 kg/d) over the experimental period. HY · D ® supplements given 6 d prior to slaughter resulted in significantly higher ( P < 0.05) initial yield values compared to supplements given 2 d prior to slaughter. Supplementation had no significant effect on meat colour, ultimate pH, sarcomere length, cooking loss, instron compression or peak force. There was a significant treatment (HY · D ®) by phenotype/HGP interaction for peak force ( P = 0.028), in which Indo-Brazil steers without previous HGP treatment responded positively (increased tenderness) to HY · D ® supplements at 2 d when compared with Indo-Brazil steers previously given HGP. There were no significant effects of treatment on other phenotypes. HY · D ® supplements did not affect muscle or plasma concentrations of calcium, potassium or sodium, but did significantly decrease plasma magnesium and iron concentrations when given 2 d before slaughter. There were no detectable amounts of 25-hydroxyvitamin D 3 in the blood or muscle of any cattle at slaughter.

Factors influencing tenderness in steaks from Brahman cattle

The objective of this study was to identify a set of explanatory variables for Warner–Bratzler shear force and myofibril fragmentation indices after 7, 14, and 21 d of aging; and sensory tenderness after 14 d of aging of steaks from Brahman cattle. Insoluble collagen was negatively associated ( P < 0.001) with all tenderness traits across aging periods, and regression coefficients ranged from 5.69 ± 0.49 to 9.12 ± 0.29 N for Warner–Bratzler shear force. The effect of lean color score ( P < 0.05) in analyses of unadjusted traits was diminished when data were adjusted for contemporary group (calves of the same sex, fed in one pen, and slaughtered the same day). Insoluble collagen may be of special importance and offer a unique opportunity to improve palatability of steaks from purebred Brahman cattle.

Genetic parameters for feed efficiency, fatness, muscle area and feeding behaviour of feedlot finished beef cattle

Feed intake (FI), weight gain (WG), metabolic weight (MW), feed conversion ratio (FCR), residual feed intake calculated by regression (RFI) and feeding standards formulae (RFIS) were recorded on 1481 steers and heifers of tropically adapted and temperate breeds of cattle feedlot finished on a grain based diet for the domestic (liveweight 400 kg), Korean (520 kg) or Japanese (steers only; 600 kg liveweight) markets. Also measured were subcutaneous fat at the rump (P8) and 12/13 rib sites, 12/13 rib eye muscle area and intra-muscular fat (IMF%), time spent eating, eating rate and number of meals per day. Estimated heritabilities of FI, MW, WG, FCR, RFI and RFIS were 0.27, 0.41, 0.23, 0.06, 0.18 and 0.13. RFI and RFIS had very high genetic (0.98) and phenotypic (0.94) correlations, suggesting that they represent very similar traits. RFI had relatively high genetic correlations with rump and rib fat (0.72 and 0.48 adjusted for age; 0.79 and 0.58 adjusted for carcase weight), but lower correlations with IMF% (0.22 and 0.25 adjusted for age and carcase weight, respectively). Selection for lower RFI is therefore possible in feedlot finished cattle, but fatness will also decrease. In this study, selection for reduced fatness was predicted to reduce RFI by more than direct selection. When appropriate, multivariate selection is therefore recommended to achieve increased feed efficiency together with the desired level of fatness, using an index including RFI, on-test weight gain and fat measurements. There were large breed differences for number of meals per day; Brahman cattle ate more frequently than Belmont Red and Santa Gertrudis breeds which ate more often than temperate breed cattle. Within breeds, there was a tendency for more efficient animals to have fewer meals per day.

Genetic parameters for growth traits in South African Brahman cattle

Genetic parameters for growth traits in the South African Brahman breed were estimated using ASREML from data records of birth weight (BWT) = 41 509, weaning weight (WWT) = 37 705, yearling weight (YWT) = 22 682 and final weight (FWT) = 13 055 collected between 1985 and 2002. The direct additive contribution to BWT, WWT, YWT and FWT were 0.28, 0.14, 0.14 and 0.18 respectively. The corresponding maternal heritability estimates were 0.11, 0.06, 0.05 and 0.03 respectively. The maternal permanent environmental component due to the dam contributed 3-7% of the total phenotypic variances of the traits under consideration. The corresponding contribution of herd-year-season x sire interaction ranges from 5% to 6%. The genetic correlation between animal effects was -0.36 for BWT. The prospects of improvement of these traits by selection seem possible and contribution of maternal permanent environment due to dam is of considerable importance as maternal effects. South African Journal of Animal Science Supp 2 2004: 44-46

Congenital myasthenic syndrome of Brahman cattle in South Africa

A congenital myasthenic syndrome in Brahman cattle is caused by a homozygous 20 base pair deletion (470del20) in the gene coding for the epsilon subunit of the acetylcholine receptor at...

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.

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.

Estimates of breed average direct, maternal and heterosis effects for some pre-weaning traits of Zebu breeds and their crosses in southeastern Mexico.

Information on 936 birth weights (BW), adjusted weaning weights (AWW) and average daily gains (ADG) from Brahman (B), Indubrazil (I), Gyr (G) and commercial Zebu (C) cattle and their crosses were obtained from the records of a farm in the State of Yucatan, Mexico. Two statistical models were used to analyse the data: the first included the effects of year and season of birth, sex of the calf, cow's parity number and breed group. The other model included the same environmental effects as the previous model and the genetic components of breed group (breed additive, breed maternal and heterosis effects). Additive and maternal effects were expressed as deviations from those for the B breed. The means of BW. AWW and ADG for the B breed were 33.3 +/- 0.64 kg, 204.0 +/- 4.9 kg and 760.06 +/- 19.24 g/day, respectively. Both models gave similar results in terms of the variance explained. Additive effects were significant (p < 0.05) for AWW and ADG but not for BW. The minor additive effect was for the C breed (-10.75 kg and 40.77 g for WW and ADG, respectively). Maternal and heterosis effects were not significant (p > 0.05) for any of the traits. The correlation between the breed group means and the means estimated by the prediction equation was r = 0.88. Finally, there was no significant genetic effect on pre-weaning calf performance among the genotypes evaluated. The genetic model can be used to predict the genotype means with a high degree of accuracy.

Selection assisted by a BoLA-DR/DQ haplotype against susceptibility to bovine dermatophilosis

Bovine dermatophilosis is a severe skin infection of tropical ruminants inducing a severe loss in productivity and a 15% mortality rate. This disease is caused by the actinomycete bacterium Dermatophilus congolensis associated with the tick Amblyomma variegatum. Currently there are no prospects for a vaccine, and acaricide or antibiotic control is hampered by the development of chemoresistance. Animal breeders have observed that dermatophilosis susceptibility seems to be determined genetically, and we previously identified a BoLA-DRB3-DQB class II haplotype marker for high (R2 = 0.96) susceptibility to the disease. With this marker, we developed a successful eugenic selection procedure for zebu Brahman cattle in Martinique (FWI). Over a period of five years, a marked reduction in disease prevalence, from 0.76 to 0.02 was achieved, and this low level has been maintained over the last two years. The selection procedure, based on a genetic marker system targeting the highly polymorphic BoLA locus, eliminates only those individuals which are at the highest risk of contracting the disease. In the present work, we discuss the properties of this system, including the "heterozygote advantage" and the "frequency dependence" theories, and examine their involvement in the biological mechanisms at the host/pathogen interface. We speculate on the exact role of the MHC molecules in the control of the disease, how the natural selection pressure imposed by the pathogens selectively maintains MHC diversity, and how our results can be practically applied for integrated control of dermatophilosis in developing countries.

Selection assisted by a BoLA-DR/DQ haplotype against susceptibility to bovine dermatophilosis.

Bovine dermatophilosis is a severe skin infection of tropical ruminants inducing a severe loss in productivity and a 15% mortality rate. This disease is caused by the actinomycete bacterium Dermatophilus congolensis associated with the tick Amblyomma variegatum. Currently there are no prospects for a vaccine, and acaricide or antibiotic control is hampered by the development of chemoresistance. Animal breeders have observed that dermatophilosis susceptibility seems to be determined genetically, and we previously identified a BoLA-DRB3-DQB class II haplotype marker for high (R2 = 0.96) susceptibility to the disease. With this marker, we developed a successful eugenic selection procedure for zebu Brahman cattle in Martinique (FWI). Over a period of five years, a marked reduction in disease prevalence, from 0.76 to 0.02 was achieved, and this low level has been maintained over the last two years. The selection procedure, based on a genetic marker system targeting the highly polymorphic BoLA locus, eliminates only those individuals which are at the highest risk of contracting the disease. In the present work, we discuss the properties of this system, including the "heterozygote advantage" and the "frequency dependence" theories, and examine their involvement in the biological mechanisms at the host/pathogen interface. We speculate on the exact role of the MHC molecules in the control of the disease, how the natural selection pressure imposed by the pathogens selectively maintains MHC diversity, and how our results can be practically applied for integrated control of dermatophilosis in developing countries.

Phylogenetic relationships of Northeast Asian cattle to other cattle populations determined using mitochondrial DNA D-loop sequence polymorphism.

Phylogenetic relationships of Northeast Asian cattle to various other cattle breeds including Bos taurus, Bos indicus, and Bison bison were assessed using mtDNA D-loop sequences. A neighbor-joining tree was constructed using sequences determined for 4 Cheju Black, 4 Cheju Yellow, 4 Korean Yellow cattle (Bos taurus), and 2 American Brahman cattle (Bos indicus), and also published sequences for 31 Japanese Black cattle, 45 European breed cattle, 6 African zebus, 2 African taurines, and 6 Indian zebus. Five American bisons (Bison bison) were used as an outgroup. The neighbor-joining tree showed that American bisons and Indian zebus are clearly separate from other cattle breeds, respectively, and African cattle clustered together, although with a low bootstrap probability (< 50%). Results indicate that cattle in Northeast Asia, Europe, and Africa are closely related to each other-suggesting their recent divergence, but are separate from Indian zebus.

Estimates of environmental effects and genetic parameters for body measurements and weight in Brahman cattle raised in Mexico

SummaryA Derivative Free Restricted Maximum Likelihood (DFREML) algorithm was used with single trait and two traits animal models to estimate the variance and covariance components and thus, heritabilities and phenotypic, genetic and environmental correlations among nine different body measurements and weights of Brahman cattle raised in Mexico. The following measurements were considered: hip width, pin width, hip‐pin width, anterior height, posterior height, body length, thorax perimeter, scrotal circumference and weight. The analysis was based on a total of 1018 animals, born between 1992 and 1995, from 17 herds in the Mexican States of Chiapas, San Luis Potosi, Tabasco, Tamaulipas and Veracruz. The model included the following fixed effects: herd, year‐season of birth, sex, age of the animal and feed management. The only random effect was the direct additive genetic contribution of each animal. All fixed effects in the model were significant for all traits (p &lt; 0.05). Estimated heritabilities for the traits were: hip width 0.57, pin width 0.32, hip‐pin width 0.41, anterior height 0.56, posterior height 0.54, body length 0.32, thorax perimeter 0.49, scrotal circumference 0.02 and weight 0.66. The magnitude of the heritabilities was medium to high, with the exception of scrotal circumference. The genetic correlations among all body measurements were consistently positive and high, ranging from 0.64 to 1.00. Although other measures showed higher genetic correlations with weight, thorax perimeter combines a high value (0.70) with ease and repeatability, making it a useful field measurement to estimate body weight when scales are not available.

Effect of salivary gland extracts from the tick, Boophilus microplus, on leucocytes from Brahman and Hereford cattle.

The effect of salivary gland extract (SGE) from Boophilus microplus on peripheral blood lymphocytes, neutrophils and monocytes from Brahman (Bos indicus) and Hereford (Bos taurus) cattle was investigated. SGE (8 micro g) significantly inhibited the proliferation response of lymphocytes to concanavalin A from both Brahman and Hereford cattle by 89% and 41%, respectively. The difference in inhibition between the two breeds was highly significant (P < 0.01), whilst at 1 micro g of SGE, significant inhibition of lymphocytes occurred only in Hereford cattle (34%). Flow cytometric analysis of monocytes and neutrophils showed that SGE (40 micro g) significantly reduced both the proportion of cells actively phagocytosing Escherichia coli labelled with fluorescein isothiocyanate (E. coli-FITC) and the uptake of E. coli-FITC in Brahman cattle. However, in Hereford cattle, a significant depression in uptake was only observed in neutrophils. The proportion of monocytes and neutrophils with oxidative activity was significantly suppressed in the presence of SGE in both breeds of cattle. These results indicate that peripheral blood leucocytes from different breeds of cattle respond differently to SGE.

Relationships of metabolic hormones and serum glucose to growth and reproductive development in performance-tested Angus, Brangus, and Brahman bulls.

Understanding mechanisms that regulate growth and reproduction are important for improving selection strategies in cattle. In this study, Angus, Brangus, and Brahman bulls (n = 7 per breed) of similar age were selected from a group of 65 weanlings. Bulls were evaluated after weaning (i.e., approximately 6 mo of age) for 112 d for serum concentrations of metabolic hormones and glucose, growth, and reproductive traits. Performance data and blood sera were collected on d 0, 28, 56, 84, and 112. Sera were also collected in periods from d 50 to 59 (56D) and 103 to 112 (112D). Angus bulls were heavier (P < 0.05) throughout the study than Brahman bulls and were heavier than Brangus bulls on d 56, 84, and 112. Initial and final BW for Angus, Brangus, and Brahman bulls were 292.7, 260.6, and 230.4 and 468.3, 435.6, and 350.7 +/- 12 kg, respectively. Conversely, Brahman bulls had greater hip height (P < 0.05) than Brangus, and Brangus were taller (P < 0.05) than Angus. Angus bulls had the greatest (P < 0.05) scrotal circumference (SC) and Brahman bulls the least. Mean SC across days was 31.5, 29.7, and 25.0 +/- 0.6 cm for the three respective breeds. Serum testosterone was greater (P < 0.01) in Angus and Brangus bulls (10.0 and 8.9 +/- 1.4 ng/mL) than in Brahman bulls (4.0 +/- 1.4 ng/mL) throughout the study. After d 112, 100, 86, and 57% of the Angus, Brangus, and Brahman bulls passed a breeding soundness exam (P = 0.51). Serum concentrations of IGF-I and leptin were greater (P < or = 0.06) in Angus bulls on d 56, 84, and 112 than in Brangus and Brahman bulls. Serum concentrations of GH (P < 0.08) and glucose (P < 0.03) were greater in Brangus bulls than in Angus or Brahman bulls throughout the study. Prediction analyses suggested that serum concentrations of leptin could be used to predict (P < or = 0.08) BW and SC (R2 > 0.82) in the 56D and 112D periods among these breeds. Leptin was also useful in predicting (P < or = 0.09) serum concentrations of GH and testosterone in the 112D period (R2 > 0.32). Residual correlation analyses with the effect of breed removed suggested that leptin was correlated (r > or => 0.53, P < 0.05) with both SC and serum testosterone. Angus and Brahman cattle differ in phenotype, level of adiposity, and rate of sexual development. Data herein suggest that these characteristics could be due to varying mechanisms by which metabolic hormones such as leptin, GH, and(or) IGF-I are regulated.

Processing and sensory characteristics of cooked roast beef: effect of breed, age, gender and storage conditions

Two separate experiments investigated the effect of breed ( Bos indicus, Bos indicus×and Bos taurus), gender/age and chilled and frozen storage on the processing characteristics of roasts made from inside rounds ( semimembranosus, adductor and gracilis muscles). Roasts were injected with a salt/phosphate brine and cooked to an internal temperature of 63 °C. Freezing the meat increased purge lost from the raw meat. Country of origin had no significant effect on cook yield. Sensory evaluations with a US consumer panel indicated only slight sensory differences due to country of origin and breed but a significant effect from storage regime. Tenderness comparisons between breeds were confounded by country of origin and indicated that roast beef from inside rounds from Brahman cattle had lower WBS values than roast beef made from inside rounds from British cattle. Although breed and age/gender often significantly affected processing characteristics of the roasts, differences were small and would have little practical or economic importance for selecting the type of meat for this market sector.

Metabolic characteristics of multiparous Angus and Brahman cows grazing in the Chihuahuan Desert.

Understanding metabolic differences between breeds of cattle is important when selecting for production in semiarid environments. Spring-calving multiparous Angus and Brahman cows (n = 8/breed) grazing in the Chihuahuan Desert were used to evaluate metabolic hormone status in February (i.e., 3rd trimester of pregnancy), May (i.e., early lactation), and September (i.e., late lactation) 2000. Crude protein in ruminal digesta collected from grazing companion ruminally cannulated cows during these months was 5.6, 6.0, and 10.3%, respectively. Angus cows were heavier (P < 0.01) than Brahman cows across months. Body condition scores among breed groups were 4.4, 3.6, and 4.6 in February, May, and September with Brahman cows tending (P < 0.10) to have greater body condition than Angus cows in May. Brahman cows tended to have greater fecal output per 100 kg BW than Angus cows in February (0.9 > 0.7 +/- 0.1, P < 0.10). Brahman cows had greater serum concentrations of leptin than Angus cows in September (1.8 > 0.70 +/- 0.1 ng/mL; P < 0.05), and serum concentrations of insulin were greater (P < 0.01) in Brahman than Angus cows throughout the study. Brahman cows also had greater (P < 0.01) serum concentrations of glucose during February and May than Angus cows. Serum concentrations of triiodothyronine were greatest (P < 0.01) during September and lowest during February and May in both breed groups and were greater (P < 0.01) in Brahman than in Angus cows in February, May, and September. Pregnancy rate and 205-d adjusted weaning weights were similar (P > or = 0.46) among breed groups. Results suggest that Brahman and Angus cows are sensitive to the seasonal dynamics of forage quality in the Chihuahuan Desert. Brahman cattle appear to have greater concentrations of metabolic hormones and metabolites than Angus cows in this environment, but Angus cows experience greater fluctuations in BW.

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