Meat quality and transport stress of cattle

This study evaluated the effect of transport time up to 14 hours and the effects of vehicle design on animal welfare, stress and meat quality. 18 transports (six short, medium and long) with a total of 486 animals (118 sample animals, heifers and bulls) were carried out on commercial vehicles in summer 2000 and winter 2001. Animal welfare and stress were evaluated by blood serum parameters, heart rate monitoring, behaviour recording and occurrence of carcass bruising. Meat quality was evaluated by post mortem muscle glycogen content, pH value, temperature, drip loss, colour and tenderness measurements. Heifers had lower heart rates than young bulls during loading (95 vs 114 beats per minute, bpm), whereas during transport, both had an average heart rate of 100 bpm, furthermore during unloading, heifers had higher heart rates than bulls (109 vs 100 bpm). Blood sampling during unloading could have marginally increased heart rates during the unloading procedure. Studied cattle had lower heart rates during medium and long distance transports compared with short transports. Monitoring of animal behaviour during transport showed that the former settled down faster than the latter. Single- and two-animal pens in medium and long distance vehicles prevented nervous and stressful movements of cattle, which were more prominent in large pens of short distance lorry. Present results suggest that larger pens of three or four animals could increase cattle stress during transport. Moreover during unloading, cattle loaded in single- or two-animals pens had significantly lower blood cortisol content than those loaded in larger groups of three or four animals (P < 0.01). The amount of severe carcass bruising was highest in animals transported over short times and loaded into groups of four cattle. Severe damages occurred most often on perianal and hipbone area of the carcass surface. Present results showed that muscle glycogen level was highest after long transport. These animals were fed more regularly from the last feeding up to stunning than medium or short distance animals. Animals in single-pens had the highest muscle glycogen level. Transport distance or number of animals in one pen had a minor effect on muscle pH values or temperatures during 24 hours post mortem (pm). Drip loss of the M. longissimus dorsi (LD) was highest after long transport, but animal number in one pen had no effect on drip loss. Colour of the LD muscle was independent on transport conditions. Light colour of three animal groups resulted from high amounts of heifers, which had lighter colour than bulls. All meat samples were quite tender. However, heifers had significantly tender meat than young bulls (P < 0.001). Higher amounts of heifers had the most tender meat after short transports. Mean DFD (dark, firm, dry) meat occurrence was 2.1% in this project, DFD frequency was lowest after short, then after long and highest after medium distance transports. Because of not evenly distributed numbers of bulls (low) and heifers (high) it was difficult to compare short and long distance transport effects.     

Inheritance of pulmonary arterial pressure in Angus cattle and its correlation with growth

Pulmonary arterial pressure (PAP) is an indicator of resistance to blood flow through the lungs and when measured at high altitude is a reliable predictor of susceptibility of an animal to brisket disease, a noninfectious cardiac pulmonary condition. (Co)-variance components for PAP, birth weight, and adjusted 205-d weaning weight were estimated from 2,305 spring-born, registered Angus cattle from a Colorado ranch at an elevation of 1,981 m. A single measure of PAP was collected after weaning on animals born from 1984 to 2003. The same licensed veterinarian measured every animal. Multitrait animal models with and without PAP maternal effects were fitted for a pedigree including 132 sires and 793 dams. The interaction of year x sex was a significant fixed effect (P <0.05) for PAP, but age of dam was not. Age at PAP testing was a significant (P <0.1) linear covariate for PAP, and scores increased 0.012 +/- 0.007 mmHg X d(-1) of age. Heritability of PAP direct was 0.34 +/- 0.05. Maternal heritability converged to a boundary at 0.0, and the model with maternal genetic effects for PAP was not significantly better than a model with only direct effects. Phenotypically, PAP was uncorrelated with birth or weaning weights. Genetically, PAP appeared to have positive, unfavorable relationships with direct effects for birth (0.49 +/- 0.12) and weaning weight (0.50 +/- 0.18). Positive correlations imply sires whose offspring exhibited resistance to brisket disease had lower weights and gains. A model that evaluated PAP in females and males as different traits had heritability estimates for each sex of 0.38 +/- 0.07 and 0.46 +/- 0.09, respectively, with a genetic correlation of 0.64 +/- 0.12 between the sexes and was not significantly better than the model assuming homogeneity by sex and a unit genetic correlation between sexes. The results suggest that PAP is moderately heritable in spring-born Angus cattle acclimatized and tested at high altitude, and selection for low PAP scores would be effective. Selection for growth at low altitude will produce cattle less suited to high altitude.     

IgM rheumatoid factor in cattle immunized against babesiosis.

Polyclonal bovine IgM-rheumatoid factors (IgM-RFs) were examined in sera of cattle immunized against babesiosis. An enzyme-linked immunosorbent assay (ELISA) was used enabling rapid screening of serum samples. Results obtained indicate a rise of serum IgM-RF levels with age in healthy bovines. However when animals of similar age and pertaining to the same herd were examined, levels of serum IgM-RF exhibited a wide distribution range. Mean values in 60 sera of 2 yrs old clinically healthy heifers originating from a single herd were of 452.60 +/- 201.26 e.u. at 1 in 1,000 serum dilution and of 202.37 +/- 137.86 e.u. at 1 in 4,000 serum dilution. In a herd where repeated vaccination of dams against babesiosis was carried out 3 to 6 weeks before delivery either with live Babesia bovis parasites or soluble antigens of in vitro grown organisms, no significant differences in mean IgM-RF values were found between revaccinated animals and a control group. Nor did the mean values of serum IgM-RF of calves born to the respective groups of dams exhibit significant differences. It thus appears that immunization of healthy cattle against this parasite does not affect mean serum IgM-RF levels.     

Behavior of feedlot cattle affects voluntary oral and physical interactions with manila ropes

Providing cattle with access to manila ropes has shown promise as a means of monitoring zoonotic bacteria in pens of feedlot cattle. Studies were conducted to determine the impacts of climate, animal age and BW, number of ropes, duration of placement, and previous rope access on efficacy of ropes as a sampling technique for feedlot cattle. Eight pens of commercial finishing cattle (average 196 +/- 19 animals per pen, 536.7 +/- 22.9 kg) were monitored for a total of 7 d in October of 2003 (commercial study). One rope was tied on the pen railing adjacent to the feed bunk in each pen, and the proportion of animals within the pen contacting the rope was recorded. In a second study, 80 cattle housed in 8 pens (each 270 m(2); 10 animals/pen) were monitored for 1 d/wk using video cameras (video study). Video images were collected for 8 consecutive weeks immediately after weaning (average BW = 252.7 +/- 30.6 kg) and for 6 wk at the end of the finishing period (average BW 541.2 +/- 42.8 kg). In the commercial study, the proportion of cattle contacting the rope per pen increased over the first 6 h to 70% (P < 0.05), although approximately 50% of the cattle contacted the rope within 2 h after placement. A 40 degrees C reduction in ambient temperature on d 6 caused cattle to cease contact with the ropes, although after 6 d of acclimation to reduced ambient temperature, interactions with ropes recovered to 47% of previous values. In the video study, weaned calves required 2 wk of acclimation to the feedlot environment before contact with the rope was maximized. Contact with the rope was most frequent 3 to 8 wk after entry into the feedlot and decreased (P < 0.05) as cattle approached slaughter weight. It is likely that ropes will be most effective at monitoring zoonotic bacteria in pens of cattle during the mid-feeding period where the pen environment is stable and cattle are inquisitive but not highly reactive.     

Peripheral circulating insulin-like growth factor-I and -II in cattle

Interrelationships between circulating concentrations of the insulin-like growth factors (IGF-I and IGF-II) were investigated in 235 blood samples taken from 145 healthy beef or dairy calves, bulls and cows of different breeds and ages. Autoradiography of Western ligand blots indicated different IGF binding protein (IGFBP) profiles between sera from different categories of cattle. Each IGF radioimmunoassay was validated by determining the effects of IGFBPs, ligand and contraligand, as well as serial dilution and comparison with results obtained after molecular sieve chromatography in acid. In female cattle mean values for IGF-I varied from 5.1 nmol/l in postparturient Holstein cows to 18.5-20.5 nmol/l in growing beef heifers, while mean IGF-II concentrations ranged from 30.0 nmol/l in the cows to 14.7-15.7 nmol/l in the beef heifer calves. In male cattle mean serum IGF-I ranged widely from 8.2 nmol/l in 1-day-old Holstein calves to 67.4 nmol/l in 16-month-old Simmental-type bulls. Mean IGF-II concentrations decreased from 22.9 nmol/l in 1-day-old Holstein bull calves to 11.9 nmol/l in 12-month-old beef bulls. Thus, total molar IGF concentrations were fairly stable in female cattle (24.7-35.1 nmol/l) but extended from 27.3 nmol/l to 81.8 nmol/l in the male cattle. The tendency for a reciprocal relationship between serum concentrations of these growth factors was most obvious in the periparturient cows.     

Influence of frame size and body condition score on performance of Brahman cattle

The effects of frame size (FS) and body condition score (BCS) on performance of Brahman cows were evaluated using records collected from 1984 to 1994 at the Subtropical Agricultural Research Station, Brooksville, Florida. Age at puberty (AP), calving rate (CR), calving date (CD), survival rate (SR), weaning rate (WR), birth weight (BWT), weaning weight (WWT), preweaning ADG, and kilograms of calf produced per cow exposed (PPC) were obtained from first- (n = 215), second- (n = 130), and third or greater-parity (n = 267) dams. Based on hip height at 18 mo of age, heifers were assigned to three FS groups: small (115 to 126 cm), medium (127 to 133 cm), or large (134 to 145 cm). Small and medium FS heifers attained puberty at younger (P<.05) ages (633.2+/-12.3 and 626.4+/-12.0 d) than large FS heifers (672.3+/-17.1 d). Calving rate in large FS second-parity dams was 27% less (P<.05) than in small and medium FS dams. In third or greater-parity dams, CR was greater (P<.05) for small FS cows than for medium and large FS cows. Across the three parity groups, CR improved with increasing BCS. Except for the first-parity dams, animals with better fall BCS calved earlier (P<.05). In first-parity dams, SR was less (P<.01) in large (47.9+/-11.0%) than in small (80.7 +/-5.2%) and medium (83.4+/-4.7%) FS groups. Weaning rates of large FS first- and second-parity dams were less (P<.05) than those of small and medium FS dams. Second-parity dams with BCS 3 had lower (P<.05) WR than dams with BCS 4 and 5. Within first- and third or greater-parity dams, BWT of calves born to small FS cows were the lightest, and those born to large FS dams were the heaviest; those born to medium FS dams were intermediate (P<.05). In second-parity dams, BWT of calves of large FS dams were greater (P<.05) than those of small and medium FS dams. In first-parity dams, calves weaned by small FS cows had lower (P<.05) WWT than those weaned by higher FS cows. In the third or greater-parity group, large FS dams weaned heavier calves (P<.05) than other dams. In all parity groups of dams, calves out of large FS cows had greater ADG (P<.05) than those from small and medium FS cows. In first-parity dams, PPC was comparable between small and medium FS dams, but both tended to be greater (P<.10) than PPC of large FS dams. Small and medium FS females reached puberty at an earlier age, calved earlier, and had greater calving, survival, and weaning rates, as well as greater kilograms of calf produced per cow exposed than the large FS females. As the large FS cows matured, they seemed to have overcome the negative effects imposed by FS that were observed at younger ages. Their performance traits were generally all comparable to those of smaller cows once they had reached maturity.     

Trace elements in grass, cattle liver and sheep liver from districts surrounding Karatina, Kenya. I. Selenium

Samples of grass, cattle and sheep livers from the districts surrounding Karatina, Kenya, were analysed for their contents of selenium. The following mean values were found: Grass (n = 31): 0.19 +/- 0.17 mg Se/kg on dry matter basis, cattle liver (n = 96): 0.31 +/- 0.10 mg Se/ kg on wet weight, and sheep liver (n = 93): 0.55 +/- 0.25 mg Se/kg on wet weight. It is concluded that selenium deficiency is unlikely to occur in the districts included in this investigation.     

Investigations on renal excretion of sodium in dairy cattle

Serum and urine were taken from healthy dairy cattle from 22 different farms. 214 animals belonged to the Swiss Brown breed and 210 were crossbreds of Simmental-Red Holstein. The animals were given at least 70 g of sodium chloride with their daily feed ration. On 6 farms sodium chloride was offered ad libitum in form of licks, which was presumed to be sufficient for covering their needs. Concentrations of sodium (UR Na), potassium (UR K) and creatinine were analyzed from serum and urine and fractional excretion of Na and K was calculated. Concentrations of sodium and potassium in urine from all cows (mean +/- sd) was 60.9 +/- 44.7 mmol/l and 370.7 +/- 66.9 mmol/l respectively. The FE values were 0.954 +/- 0.939% for sodium and 173.1 +/- 54% for potassium. In 5.5% of the animals values for UR Na < 10 mmol/l were found. There were no significant differences, however, were found in sodium and potassium excretion among farms. Urine samples of at least 10 animals should be analyzed in order to have a reliable estimation of the supply with sodium chloride within a herd. Our results do not support the hypothesis that low sodium excretion would be a predisposing factor for Bovine Dilative Cardiomyopathy in Simmental-Red Holstein cattle.     

Multi-trait and random regression approaches for addressing the wide range of weaning ages in Asturiana de los Valles beef cattle for genetic parameter estimation

Weaning weight (WW) records of 24,066 Asturiana de los Valles beef cattle, including the progeny of 557 sires and 10,653 dams, were analyzed using a multitrait animal model (MAM) and a random regression model (RRM) in order to estimate the variance components and the breeding value of the animals. Three definitions of WW were used: early weaning (EW) for animals weaned before the age of 180 d; standard weaning (SW) for animals weaned between 180 and 240 d old; and late weaning (LW) for animals weaned between the ages of 240 and 365 d. The heritabilities (h(2)) were high (from 0.49 to 0.63), which fully agrees with previous estimates for this breed. The genetic correlations between EW and SW were 0.86, and lower between EW and LW at 0.543 to 0.622, using MAM and RRM models, respectively. Ranking of sires displayed changes depending on age at weaning of their offspring, which could explain the modest genetic progress reached using MAM evaluation. The first 2 eigenvalues of the random regression coefficient matrix explained 66 and 30% of the genetic variance, which implies important genetic variation underlying the form of the growth curve of the animals during the weaning period. The evaluation of sires according to the official method, as currently carried out by the breeders' association (WW adjusted previously to the age of 180 d), does not exploit the genetic differences in response to their production system where the calf is weaned at variable ages.     

Clinical evaluation of growth hormone secretion in cattle using insulin tolerance test

Growth hormone secretion was evaluated in cattle. Clinically healthy bovine growth hormone (bGH) concentrations were 10.7 +/- 1.6 ng/ml in Holstein and 7.8 +/- 3.9 ng/ml in Japanese black cattle. The bGH concentration alternated at three-hour intervals, and tended to be higher at midnight and lower in the morning and before feeding. Insulin tolerance test (ITT) at an insulin dosage of 0.25 U/kg showed a significant increase of bGH concentration to 331 +/- 153% at 60 to 90 min after injection. In ITT applied to five under-growth calves of Japanese black cattle, the basal bGH concentrations were lower and peak values after insulin injection were shown to be significantly low. The ITT is useful for the clinical examination of bGH secretion in cattle.     

Illustration of the maternal animal model used for genetic evaluation of beef cattle

National cattle evaluation programs for weaning weight in most beef breed associations involve implementation of the maternal animal model to predict direct and maternal EPD. With this model, direct breeding values are predicted for all animals with records or pedigree ties to animals with records, or both. Even though maternal genetic value is expressed only in animals that become dams, these effects are transmitted by all parents and inherited from parents by all animals, leading to maternal breeding values being predicted for all animals as well. A small example data set was simulated involving 12 parents, 8 nonparents, and 13 animals with weaning weight records. The pedigree was developed to include paternal and maternal half-sib families, full-sibs, and some inbreeding, similar to field populations of beef cattle. Assembly of the mixed model equations and solutions for the maternal animal model are illustrated explicitly to assist animal breeding students in their understanding of the properties of the maternal animal model and to explicitly implement the model. Model parameters and moments, fixed contemporary group solutions, adjustment of breeding values for merit of mates, interpretation of maternal permanent environmental effect solutions, and alternatives for the assembly of the equations are shown. This example should lead to increased student and producer understanding of genetic improvement programs for weaning weight in beef cattle.     

The effect of litter size before weaning on subsequent body development, feed intake, and reproductive performance of young rabbit does

An experiment was performed to study the effect of litter size before weaning on subsequent body development and composition, feed intake, and reproductive performance of young rabbit does with the objective to improve reproductive performance. Litter size (LS) before weaning (treatment) was 6, 9, or 12 kits. After weaning (30 d), 58 female kits per treatment (in two successive replicates) were reared and fed for ad libitum intake to 14.5 wk of age (end of rearing). At 14.5 wk of age, receptive does were inseminated. Nonreceptive and nonpregnant does were inseminated at 17.5 wk of age. The experiment ended when the second litter was weaned. Part of the animals was slaughtered to determine body composition at the end of the experiment (replicate one) and at the end of rearing (replicate two). At weaning, BW differed among treatments (P < 0.05; 855, 773, and 664 +/- 15 g for LS6, 9, and 12, respectively). Compensatory growth was observed. At the end of rearing, LS12 does were smaller (P < 0.05) than LS9 and LS6 does (3,524, 3,778, and 3,850 +/- 48 g, respectively). After first lactation, no difference in BW among treatments was found. Compared with LS6, empty body weight (BW minus gut, bladder, and uterus content) of LS12 contained more (P < 0.05) nitrogen (32.5 vs 31.1 +/- 0.3 g/kg), more (P < 0.05) ash (30.7 vs 28.3 +/- 0.6 g/kg), and less (P < 0.05) fat (168.6 vs 200.2 +/- 8.6 g/kg). No differences in body composition among treatments were found at the end of the experiment. During rearing, LS12 had the lowest (P < 0.05) daily feed intake (152, 164, and 169 +/- 2 g/d for LS12, 9, and 6, respectively). During the reproductive period, no differences in feed intake among treatments were found. Kindling rate (the number of kindlings per number of inseminations) was not influenced by treatment. In the first parity, total litter size (number of alive and stillborn kits) was lower (P < 0.10) for LS12 than for LS9 (6.4 vs 8.6 +/- 0.5, respectively). When first mating was delayed by 3 wk, an increased (P < 0.05) total litter size was found regardless of treatment (7.5 and 9.4 +/- 0.3 for 14.5, and 17.5 wk, respectively). Decreasing litter size before weaning from nine to six kits did not alter future reproductive performance. Based on results of this study, it seems advisable to perform a limited standardization level (at nine kits) after kindling and postpone first mating to an older age (17.5 wk) to improve reproductive performance.     

Association of myostatin on early calf mortality, growth, and carcass composition traits in crossbred cattle

The objective of this study was to investigate a potential association of an inactive myostatin allele with early calf mortality, and evaluate its effect on growth and carcass traits in a crossbred population. Animals were obtained by mating F1 cows to F1 (Belgian Blue x British Breed) or Charolais sires. Cows were obtained from mating Hereford, Angus, and MARC III (1/4 Hereford, 1/4 Angus, 1/4 Pinzgauer, and 1/4 Red Poll) dams to Hereford, Angus, Tuli, Boran, Brahman, or Belgian Blue sires. Belgian Blue was the source of the inactive myostatin allele. Myostatin genotypes were determined for all animals including those that died before weaning. Early calf mortality was examined in the F2 subpopulation (n = 154), derived from the F1 sires mated to F1 cows from Belgian Blue sires, to evaluate animals with zero, one, or two copies of inactive myostatin allele. An overall 1:2:1 ratio (homozygous active myostatin allele:heterozygous:homozygous inactive myostatin allele) was observed in the population; however, a comparison between calves dying before weaning and those alive at slaughter showed an unequal distribution across genotypes (P < 0.01). Calves with two copies of the inactive allele were more likely (P < 0.01) to die before weaning. Postweaning growth traits were evaluated in the surviving animals (n = 1,370), including birth, weaning, and live weight at slaughter, and postweaning ADG. Carcass composition traits analyzed were hot carcass weight, fat thickness, LM area, marbling score, USDA yield grade, estimated kidney, pelvic, and heart fat, retail product yield and weight, fat yield and weight, bone yield and weight, and percentage of carcasses classified as Choice. Charolais lack the inactive myostatin allele segregating in Belgian Blue; thus, in the population sired by Charolais (n = 645), only animals with zero or one copy of the inactive myostatin allele were evaluated. Animals carrying one copy were heavier at birth and at weaning, and their carcasses were leaner and more muscled. In the population sired by Belgian Blue x British Breed (n = 725), animals with two copies of inactive myostatin allele were heavier at birth, leaner, and had a higher proportion of muscle mass than animals with zero or one copies. Heterozygous animals were heaviest at weaning and had the highest live weight, whereas animals with zero copies had the highest fat content. The use of the inactive myostatin allele is an option to increase retail product yield, but considerations of conditions at calving are important to prevent mortality.     

Blood thiamine levels in normal cattle and sheep at pasture

Analysis of whole blood samples from 174 cattle and, 174 sheep from 3 geographical regions of New Zealand over a 10 month period showed a mean (range) thiamine level of 122 nmol/l (71-237 nmol/l) for cattle and 118 nmol/l (67-227 nmol/l) for sheep. Regional and seasonal differences were noted with levels tending to rise over the summer period. A reference range of 75-185 nmol/l is proposed for both cattle and sheep to cover these variations. Levels below 50 nmol/l are considered indicative of deficiency.     

Selection for weaning weight and postweaning gain in Hereford cattle. II. Response to selection

Single trait selection was practiced in three lines of Hereford cattle at two locations. Bulls were selected within sire families for increased weaning weight (WW) in the WW line (WWL), for postweaning gain (PG) in the PG line (PGL) and at random in the control line (CTL). Data include the performance of 2,467 calves produced from 1967 to 1981. Environmental effects were estimated from CTL (method I) and from multiple regression procedures (method II). Phenotypic and environmental time trends were negative for WW and generally were positive for PG. Estimated genetic gains for WW in WWL were 1.07 +/- .51 kg/yr in bulls and .62 +/- .36 kg/yr in heifers using method I and .50 +/- .31 kg/yr in bulls and .10 +/- .17 kg/yr in heifers using method II. Corresponding values for PG in PGL were .85 +/- .40 and 1.03 +/- .24 kg/yr in bulls and .30 +/- .28 and .37 +/- .12 kg in heifers. Correlated genetic gains for WW in PGL were larger than direct WW gains, whereas genetic gains for PG in WWL were smaller than direct PG gains. From method I, estimates of realized heritability (h2R) for WW were .31 +/- .18 in bulls and .22 +/- .13 in heifers. For PG, h2R was .31 +/- .13 in bulls and .06 +/- .12 in heifers. Using method II, h2R for WW was .09 +/- .08 in bulls and .02 +/- .07 in heifers. Corresponding values for PG were .29 +/- .10 and .11 +/- .08. Joint estimates of the realized genetic correlation between WW and PG were .69 +/- .18 and .46 +/- .31 for methods I and II, respectively. Variation in selection response was evaluated using quasi-replicates. Results of this study indicate that selection for PG improved both WW and PG faster than selection for WW.     

Additive genetic relationships between heifer pregnancy and scrotal circumference in Nellore cattle

To estimate heritability (h2) for yearling heifer pregnancy and to estimate the genetic correlation between heifer pregnancy and scrotal circumference, 18,145 records of Nellore heifers exposed to breeding at an age of approximately 14 mo and 25,466 records of contemporary young bulls were analyzed. Heifer pregnancy was considered as a categorical trait, with the value 1 (success) assigned to heifers that were pregnant after rectal palpation approximately 60 d after the end of a 90-d breeding season and the value 0 (failure) otherwise. A single-trait animal model for heifer pregnancy and a two-trait animal model including heifer pregnancy and scrotal circumference were used. Contemporary groups were defined in two ways: including (CG2) or not including (CG1) weaning management of the heifer. Heritability estimates obtained by Method R in single-trait analyses were 0.68 +/- 0.09 and 0.61 +/- 0.10 using CG1 and CG2 definitions, respectively. Heritability estimates for two-trait analyses were 0.69 +/- 0.09 (CG1) and 0.63 +/- 0.08 (CG2) for heifer pregnancy and 0.57 +/- 0.03 (both CG) for scrotal circumference. The genetic correlation estimates between the two traits were 0.20 +/- 0.12 (CG1) and 0.20 +/- 0.13 (CG2). Based on the results of this study, EPD for heifer pregnancy can be used to select bulls for the production of precocious daughters and will be more effective than selecting on scrotal circumference EPD in Nellore cattle. However, scrotal circumference can be incorporated in a two-trait analysis to increase the accuracy of prediction for heifer pregnancy EPD for young bulls. Using contemporary group without heifer weaning management gave higher h2 and, for two-trait analysis, converged more quickly.     

Genetic relationships among calving ease, calving interval, birth weight, and weaning weight in the Asturiana de los Valles beef cattle breed

The aim of this paper was to estimate direct and maternal genetic parameters for calving ease (CE), birth weight (BrW), weaning weight (WW), and calving interval (CI) to assess the possibility of including this information in beef cattle improvement programs. Field data, including a total of 59,813 animals (1,390 sires and 1,147 maternal grand sires) from the Asturiana de los Valles beef cattle breed, were analyzed with a multivariate linear model. Estimates of heritability for direct genetic effects (CED, CID, BrWD, and WWD) were 0.191 +/- 0.019, 0.121 +/- 0.013, 0.390 +/- 0.030, and 0.453 +/- 0.035, respectively, whereas those for maternal genetic effects (CEM, BrWM, and WWM) were 0.140 +/- 0.015, 0.208 +/- 0.020, and 0.138 +/- 0.022, respectively. Genetic correlations between direct or maternal genetic effects across traits were, in general, positive and moderate to low. However, genetic correlation for the pair CED-BrWD was positive and high (0.604 +/- 0.064). Genetic correlations between the direct and maternal genetic effects within a trait were negative and moderate (-0.219 +/- 0.097 for CE, -0.337 +/- 0.080 for BrW, and -0.440 +/- 0.102 for WW). Genetic correlations for CED-BrWM and CED-WWM were -0.121 +/- 0.090 and -0.097 +/- 0.113, respectively. The genetic correlation for CEM-CID was unfavorable (0.485 +/- 0.078), and those for CEM-BrWD (-0.094 +/- 0.079) and CEM-WWD (-0.125 +/- 0.082) were low and negative. The genetic correlation between CID and WWM was favorable (-0.148 +/- 0.106). Overall, the data presented here support the hypothesis that maternal effects for CE and BrW are not the same and that the genetic relationships between CI and maternal effects for WW in beef cattle follow a similar pattern to that reported between CI and milk yield in dairy cattle. Moreover, the need to include direct and maternal breeding values in beef cattle selection programs is suggested.     

Estimates of genetic parameters for live animal ultrasound, actual carcass data, and growth traits in beef cattle

Growth and carcass measurements were made on 2,411 Hereford steers slaughtered at a constant weight from a designed reference sire program involving 137 sires. A second data set consisted of ultrasound measures of backfat (USFAT) and longissimus muscle area (USREA) from 3,482 yearling Hereford cattle representing 441 sires. Restricted maximum likelihood procedures were used to estimate genetic parameters among carcass traits and live animal weight traits from these two separate data sets. Heritability estimates for the slaughter weight constant steer carcass backfat (FAT) and longissimus muscle area (REA) were .49 and .46, respectively. In addition, FAT had a negative genetic correlation with REA (-.37), weaning weight (-.28), and yearling weight (-.13) but positive with marbling (.19) and carcass weight (.36). Marbling was moderately heritable (.35) and highly correlated with total postweaning average daily gain (.54) and feedlot relative growth rate (.62). Heritability estimates for weight constant USFAT and USREA were .26 and .25, respectively. The genetic correlation between weight constant USFAT and USREA was positive (.39), indicating that in these young animals USFAT does not seem to be an indication of maturity. Mean USFAT measures and variability were small (.48 +/- .17 cm, n = 3,482). Results indicate that carcass fat on slaughter steers and ultrasound measures of backfat on young breeding animals may have different relationships with growth and muscling. These relationships need to be explored before wide scale selection based on ultrasound is implemented.     

Serum haptoglobin concentration in cattle

To obtain a basal concentration of serum Haptoglobin (Hp) in cattle in Taiwan, Hp concentrations were measured from serum samples collected from 10 healthy heifers, every week for one year. The values were also compared with those collected from 15 cows diagnosed with postpartum metritis. The heifers were successfully impregnated by artificial insemination six months after the tests. Hp concentrations were also measured in the serum collected from 11 other cows within 3 weeks after parturition. The Hp assay developed in this study gave a good correlation (r=0.893)with Western blotting. The Hp concentration of 454 serum samples from the 10 heifers had a mean value of 83.6 +/- 34.1 mg/l, and there was no significant difference among individual heifers. The basal value of Hp in heifers was calculated as less than 73.6 mg/l. No significant difference in Hp concentration was observed among the 10 heifers during cold and warm seasons (19.8 +/- 2.2 degrees C vs 27.3 +/- 1.4 degrees C), or before and after pregnancy. The mean serum Hp concentration from cows suffering from postpartum reproductive disorders was 1133.5 +/- 627.1 mg/l, which was significantly greater than the serum of healthy heifers and postpartum cows (104.6 +/- 61.0 mg/l) (P<0.05). These results demonstrate that Hp concentration may be a useful indicator for cows with postpartum reproductive disorders.     

Hepatic failure and hemochromatosis of Salers and Salers-cross cattle

Hemochromatosis is rare in domestic mammals. Five clinical cases and one preclinical case of hemochromatosis were diagnosed in Salers and Salers-cross cattle. Clinical disease developed between 9 and 22 months of age. Animals were healthy until weaning but then lost weight, developed rough hair coats, and lost incisor teeth. In two animals, hemochromatosis was identified by liver biopsy, biochemical evidence of hepatic injury, and/or elevated transferrin saturation values. At necropsy, carcasses were thin, with firm dark brown livers and lymph nodes, soft bones, and brown-colored small bowel. The principal histologic changes were hepatocellular siderosis and periportal, bridging, and perivenular fibrosis. Siderocalcinosis involved collagen, elastin, reticulin, and basement membrane components in liver, lymph nodes, spleen, duodenum, and kidney. Hepatic iron concentrations in clinically affected cattle were 1,500-10,500 microg/g wet weight (reference range for cattle = <300 microg/ g). Ultrastructurally, the heaviest intrahepatic deposition was in hepatocytes, which contained large intracytoplasmic siderosomes. Iron deposition in bone was associated with osteopenia. Genetic analysis indicated a common ancestral bull in the pedigrees of five of six affected cattle; no pedigree was available for the remaining animal. Four dams of five affected animals were phenotypically normal and had histologically normal livers. Test mating of four cows to the ancestral bull resulted in a female calf that developed clinicopathologic and histologic evidence of preclinical hemochromatosis by 40 days of age. It was not possible to establish the pattern of inheritance because of the small number of pedigrees from affected cattle.