Performance of crosses among Hereford, Angus and Simmental cattle with different levels of Simmental breeding: IV. Maternal heterosis and calf production by two-year-old dams

The performance of 264 contemporary 2-yr-old straightbred and crossbred dams during 1978 to 1981 was studied and maternal heterosis was estimated. Dam breed groups were Hereford (HH), Angus-Hereford (AH), 25% Simmental-75% Hereford (1S3H), 50% Simmental-50% Hereford (1S1H) and 75% Simmental-25% Hereford (3S1H). Differences among dam breed groups were nonsignificant for length of gestation, calving difficulty and late milk production but were important (P less than .01) for calf weights (birth, early and late milking periods and weaning), calf average daily gains during various intervals from conception to weaning, early milk production and other calf traits at weaning (height, weight/height and visual condition score). Dam breed group means (HH, AH, 1S3H, 1S1H and 3S1H, respectively) for representative calf traits were .37, .39, .39, .42 and .42 kg/d for estimated average daily gain the last 3 mo of gestation; 33.6, 34.7, 35.7, 37.6 and 37.1 kg for birth weight; 191, 205, 209, 228 and 228 kg for weaning and 7.5, 8.4, 8.3, 9.5 and 10.0 kg for 24-h early milk production. Therefore, 2-yr-old crossbred dams raised calves that were generally larger for the preweaning gain traits than HH dams. Differences among dam breed groups were significant for traits involving reproduction; means (HH, AH, 1S3H, 1S1H and 3S1H, respectively) were .58, .92, .72, .91 and .79 for proportion calving and 105, 179, 126, 182 and 154 kg for actual calf weaning weight per cow exposed to breeding. Estimates of percentage maternal heterosis were 6.3, 12.9, 9.0 and 7.6% for calf weights at birth, 40 d, 130 d and weaning, respectively; 1.8, 5.7 and 5.7% for calf hip height, height/weight and condition score at weaning, respectively; and 43.1 and 34.6% for proportion calving and actual calf weaning weight per cow exposed to breeding. The dominance model explained most (greater than 95%) of the variation observed among dam breed group means for most traits.     

Performance of crosses among Hereford, Angus, and Simmental cattle with different levels of Simmental breeding: VI. Maternal heterosis of 3- to 8-year-old dams and the dominance model.

Data from Hereford, 25% Simmental-75% Hereford, 50% Simmental-50% Hereford, and 75% Simmental-25% Hereford dams were used to estimate maternal heterosis and level of agreement with the dominance model. Cows were located at the Northern Agricultural Research Center near Havre, MT and were managed consistent with practices for western range environments. Sample halves of dam breed groups were bred to Charolais and Tarentaise sires to produce calves at 3 to 8 yr of age. There were 766 exposures to breeding that resulted in 581 calves. Breed group means for most traits supported the dominance model. Maternal heterosis was estimated by regression techniques for 22 cow and calf traits. Maternal heterosis was not significant for day of conception, number of services, gestation length, or calving difficulty. Estimates of maternal heterosis for calf growth traits ranged from .7% for weaning height to 5.2% for weaning weight and 7.5% for weaning condition score. Calf weight per unit of cow weight at weaning showed significant maternal heterosis (7.1%). Higher levels of maternal heterosis were exhibited for milk production (8.2 to 11.1%) and the negative, but nonsignificant, estimate of maternal heterosis for early minus late milk production suggested more persistent lactation for crossbred cows. Maternal heterosis was 11.5% for proportion of dams that calved and 10.4% for proportion of dams that weaned calves. Calf weaning weight per cow exposed to breeding, a characteristic combining calf growth and dam reproduction, exhibited 17.9% maternal heterosis.     

Performance of Hereford and two-breed rotational crosses of Hereford with Angus and Simmental cattle: I. Calf production through weaning

Cow size, reproductive traits and calf performance through weaning were evaluated in a range environment for Simmental (S) x Hereford (H) and Angus (A) x H crosses in two-breed rotations and straightbred H. Data were grouped into seven dam breed categories: straightbred Hereford (H), crossbred F1 S x H cows (SH), S x H cows of low percentage H (SHS), S x H cows of high percentage H (HSH), F1 A x H cows (AH), A x H cows of low percentage H (AHA) and A x H cows of high percentage H (HAH). Straightbred H, SH, AH, SHS and AHA cows were mated to H bulls, HSH cows were mated to S bulls and HAH cows were mated to A bulls. Cows in the SHS and AHA groups ranged from 1/4 to 3/8 H and their calves from 5/8 to 11/16 H. Cows within the HSH and HAH groups ranged from 5/8 to 3/4 H and their calves from 5/16 to 3/8 H. Cow age ranged from 3 to 10 yr. Simmental-cross cows were heavier and taller and produced heavier calves at birth and weaning than A-cross. Pregnancy rate, calf birth date and percentage of difficult births did not vary significantly among dam breed groups. Within the A x H and S x H rotations, dam breed group rankings for calf birth weight were inverse to rankings for proportion of H in the breed makeup of the calf.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reproductive rates, birth weight, calving ease and 24-h calf survival in a four-breed diallel among Simmental, Limousin, Polled Hereford and Brahman beef cattle

Calving and weaning rates, birth weight, calving ease, and 24-h calf survival were evaluated in a four-breed diallel of Simmental (S), Limousin (L), Polled Hereford (H) and Brahman (B) beef cattle in five calf crops. Limousin dams tended to have the highest calving and weaning rates because they were able to have heavier calves with less calving difficulty and higher survival rates. Brahman-sired calves were the heaviest at birth (P less than .05) and B dams produced the lightest calves (P less than .001). Lower birth weights tended to be the limiting factor on survival of these calves. A linear comparison among means to evaluate purebred, additive, maternal and specific combining ability effects showed most of the reduction in birth weight from B dams was due to maternal effects. Breed of dam accounted for a higher proportion of variation in calving ease than did sire breed. Simmental sires had significantly heavier calves at birth and S and H dams tended to have more calving difficulty and lower survival rates. Heterosis for these traits was generally not significant. Correlations were generally positive and significant for birth weight and calving ease, but were more variable for birth weight and survival. Linear regressions of calving ease on birth weight both within years and within dam-breed-year subclasses were very similar in that the association of these two traits was reduced as dam age increased.     

Biological type effects on gestation length, calving traits and calf growth rate

Gestation length, birth weight calving difficulty, calf mortality rate at birth, calf mortality rate from birth to weaning, preweaning calf growth rate and calf 200-d weight were evaluated in a biological type study in which four sire breeds were bred by AI to Hereford dams. Angus and Red Poll sires represented breeds of medium size, and Pinzgauer and Simmental sires represented large breeds. Angus and Pinzgauer represented breeds with medium milk production, and Red Poll and Simmental represented breeds with high milk production. Dams mated to large sire breeds had longer (P less than .01) gestation lengths (.95 d) and higher calving difficulty scores than dams mated to medium-sized sire breeds. Calves from large sire breeds had heavier birth weight (P less than .01) and 200-d wt (6.1 kg; P less than .01) than calves from medium-sized sire breeds. Calf death loss and ADG to weaning were similar (P greater than .10) for all breeds of sire. Calves from the higher milk level sire breeds exceeded the medium-milk breeds in birth weight (1.3 kg; P less than .01) but did not (P greater than .10) in other traits. Calves from the higher milk level sire breeds exceeded the medium-milk breeds in birth weight (1.3 kg; P less than .01) but not (P greater than .10) in other traits. Interaction between size and milk production of sire breed existed for gestation length, birth weight, ADG from birth to weaning and 200-d calf weight (P less than .01). In general, mature size of sire breed was a good indication of expected performance traits not easily influenced by environment. Not all differences, however, could be explained by size and milk production of the size breed.     

Performance of crosses among Hereford, Angus and Simmental cattle with different levels of Simmental breeding. III. Heifer postweaning growth and early reproductive traits

Postweaning growth and early reproductive traits in heifers whose potential for milk production differed were studied during the years 1976 through 1979. Data were collected on 230 heifers raised by greater than or equal to 3-yr-old Hereford dams. Heifers were comprised of the following breed groups: Hereford (HH), Angus-Hereford (AH), 25% Simmental-75% Hereford (1S3H) and Simmental-Hereford (SH). Postweaning growth rate during a 140-d period was greatest for SH heifers (.75 kg/d), intermediate for AH and 1S3H groups (.70 and .68 kg/d, respectively) and slowest for HH heifers (.64 kg/d). At 1 yr of age, SH heifers were heavier, taller and had larger pelvic areas than all other groups (P less than .01). Least-squares means for yearling weight, hip height and pelvic area for HH, AH, 1S3H and SH heifers were 283, 303, 298 and 317 kg; 111, 112, 114 and 118 cm, and 132, 136, 139 and 148 cm2, respectively. Ninety-one percent of the heifers reached puberty by the end of the breeding period. Crossbred heifers reached puberty at younger ages and had higher pregnancy rates than HH heifers (P less than .01). Least-squares means for pubertal age, weight and height for HH, AH, 1S3H and SH breed groups were, respectively, 407, 371, 382 and 368 d; 300, 302, 305 and 313 kg, and 115, 114, 117 and 119 cm. Percentage of heifers reaching puberty by 14 mo of age was 64, 99, 85 and 94 for HH, AH, 1S3H and SH, respectively. Respective pregnancy rates were 59, 90, 77 and 86%, but were not significantly different among breed groups when only heifers reaching puberty by the end of the breeding period were studied. No differences among breed groups were found for date of pregnancy.     

Grazing behavior of rangeland beef cattle differing in biological type

Grazing behavior exhibited by different biological types (breed groups) of lactating beef cows was evaluated during the summers of 1985 (Trial 1) and 1986 (Trial 2). Animals grazed native Montana foothill grassland. In Trial 1, breed groups consisted of Hereford (HH), 50% Angus-50% Hereford (AH), 50% Simmental-50% Hereford (SH), and 75% Simmental-25% Hereford (3S1H) with six cows per breed group. Daily grazing hours were 11.8 +/- .2, 12.3 +/- .2, 11.6 +/- .2, and 11.6 +/- .5 h/d for HH, AH, SH, and 3S1H, respectively. There was a tendency for AH cows to graze longer than HH and SH cows (P = .10). Bite rates were 52.7 +/- 1.5, 56.2 +/- 1.5, 53.2 +/- 1.4, and 59.0 +/- 1.6 bites/min for HH, AH, SH, and 3S1H, respectively. The AH and 3S1H cows had higher bite rates (P less than .05) than the HH and SH cows. Means for distance traveled were 3.1 +/- .2, 3.4 +/- .2, 4.0 +/- .2, and 2.8 +/- .2 km/d for HH, AH, SH and 3S1H, respectively. The SH cows tended to travel farther (P less than .10) than cows of other breed groups. The AH traveled farther than the 3S1H but did not differ from the HH. In Trial 2, breed groups were Hereford (HH), Tarentaise-Hereford (TH), Tarentaise-Simmental-Hereford (T(SH], and Charolais-Simmental-Hereford (C(SH]; each group included six lactating cows. Means for bite rate were 56.9 +/- 1.1, 58.7 +/- 1.1, 60.9 +/- 1.0, and 59.0 +/- 1.1 bites/min for HH, TH, T(SH), and C(SH), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of tropically adapted sire breeds on preweaning growth of F1 Angus calves and reproductive performance of their Angus dams

The objective of this study was to determine the effect of tropically adapted sire breeds on preweaning growth performance of F1 calves and on reproductive performance of their Angus dams. Angus (A) cows were bred in two consecutive years (1992 and 1993) by AI using semen from Brahman (B; Bos indicus; n = 10), Senepol (S; Bos taurus; n = 10), and Tuli (T; Sanga; n = 9) bulls. A total of 82 B x A, 85 S x A, and 91 T x A calves were born. The statistical model included the fixed effects of year, sire breed, calf sex, sire breed x calf sex, and cow parity and the random effect of sire within sire breed. Birth weight, weaning weight, 205-d adjusted weaning weight, ADG from birth to weaning, and hip height at weaning were greater (P < .001) for B x A calves than for S x A or T x A calves. Greater differences were detected between sexes for B x A than for S x A and T x A (for all traits sire breed x calf sex, P < .05). Sire breed affected (P < .01) the percentage of unassisted calvings (B x A, 87%; S x A, 98%; and T x A, 100%) and tended (P < .10) to affect the percentage of calves that survived until weaning (B x A, 90%; S x A, 94%; and T x A, 98%). Sire breed of calf did not affect (P > .10) length of gestation, and sire breed did not affect the interval from calving to first observed estrus or pregnancy in Angus dams. These results demonstrate that preweaning growth performance of B x A calves was greater than that of either S x A or T x A calves. However, use of Brahman sires on Angus dams led to calving problems and tended to reduce the percentage of calves that survived until weaning. Thus, heavier weaning weights of B x A calves would be an advantage for cow-calf producers marketing calves, but heavier birth weights and calving difficulty attributed to Brahman sires would be a disadvantage.     

Evaluation of birth and weaning traits of Romosinuano calves as purebreds and crosses with Brahman and Angus

The objectives of this work were to evaluate birth and weaning traits, to estimate genetic effects, including heterosis and direct and maternal breed effects, and to evaluate calving difficulty, calf vigor at birth, and calf mortality of Romosinuano as purebreds and as crosses with Brahman and Angus. Calves (n = 1,348) were spring-born from 2002 through 2005 and weaned in the fall of each year at about 7 mo of age. Traits evaluated included birth and weaning weight, ADG, BCS, and weaning hip height. Models used to analyze these traits included the fixed effects of year, sire and dam breeds, management unit, calf sex, cow age, and source of Angus sire (within or outside of the research herd). Calf age in days was investigated as a covariate for weaning traits. Sire within sire breed and dam within dam breed were random effects. Estimates of Romosinuano-Brahman and Romosinuano-Angus heterosis (P < 0.05) were 2.6 +/- 0.3 (8.6%) and 1.4 +/- 0.3 kg (4.7%) for birth weight, 20.5 +/- 1.5 (9.5%) and 14.6 +/- 1.4 kg (7.4%) for weaning weight, 79.2 +/- 6.1 (9.8%) and 55.1 +/- 6.0 g (7.5%) for ADG, 0.16 +/- 0.03 (2.7%) and 0.07 +/- 0.03 (1.2%) for BCS, and 2.77 +/- 0.32 cm (2.4%) and 1.87 +/- 0.32 cm (1.7%) for hip height. Heterosis for Brahman-Angus was greater (P < 0.05) than all Romosinuano estimates except those for Romosinuano-Brahman and Romosinuano-Angus BCS. Romosinuano direct effects were negative and lowest of the breeds, except for the Angus estimate for hip height. Romosinuano maternal effects were the largest of the 3 breeds for birth weight and hip height but intermediate to the other breeds for weaning weight and ADG. A large proportion of Brahman-sired calves from Angus dams (0.09 +/- 0.03; n = 11) was born in difficult births and died before 4 d of age. Brahman and Angus purebreds and Romosinuano-sired calves from Brahman dams also had large proportions of calves that died before weaning (0.09 or greater). Results indicated that Romosinuano may be used as a source of adaptation to subtropical environments and still incorporate substantial crossbred advantage for weaning traits, although not to the extent of crosses of Brahman and Angus.     

Production characters of straightbred, F1 and F2 cows: birth and weaning characters of terminal-cross calves

Records of 2,449 births and 2,120 weanings of terminal-cross calves were used to characterize maternal productivity of first- and second-generation cows from a diallel of Angus, Brahman, Hereford, Holstein and Jersey when mated to third-breed sires. Third- and later-parity cows were randomly assigned after each parturition to Charolais and Red Poll bulls in multiple-sire pastures. Calves were weaned at approximately 7 mo of age; males were not castrated. A mixed model was assumed for data analysis. Effects included in the model were breed-type of dam, cow within breed-type of dam (random), breed of sire of calf, season of record, year of record, age of dam group, sex of calf and age of calf (covariate). Age of dam groups were 4- and 5-yr-olds, 6- and 7-yr-olds, 8-, 9- and 10-yr-olds, and those greater than 10 yr of age. Dependent variables were calf weight, shoulder width and hip width at birth, weaning weight, weaning height and survival to weaning. Holstein and Holstein crosses tended to produce the largest calves at birth and weaning. Among straightbred dams, the smallest calves were born to Brahman, whereas Hereford weaned the smallest calves. Brahman-Jersey dams produced the smallest calves at birth among crossbreds; Angus-Hereford cows weaned the smallest calves. Average maternal heterosis estimates for birth weight were small and non-significant. Calves of F1 crossbred dams were 17.4 kg heavier (P less than .01) and 1.70 cm taller (P less than .01) at weaning than calves of first-generation straightbred dams.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reproductive performance in crosses of Angus, Santa Gertrudis and Gelbvieh beef cattle

Angus (A), Santa Gertrudis (S), and Gelbvieh (G) sires were mated to A and S dams to produce five mating types (A X A, S X S, S X A, A X S and G X A) in each of four calf crops. The study involved 501 matings. Overall means for the traits measured (calves born/cows exposed, Julian birthdate, calving ease, percentage of live calves at 24 h, birth weight, survival to weaning and gestation length) were 74.2%, 48.8 d, 96.4%, 33.2 kg, 95.4% and 283.8 d, respectively. Angus dams had a 14 percentage point (P less than .05) advantage over S dams for percentage of calves born/cows exposed. The effect of heterosis in crosses of A and S for percentage of calves born/cows exposed was negative (-11.1%) and approached significance. The percentage of calves born/cows exposed were 84.4, 70.4, 76.1 and 62.3 for the A X A, S X S, S X A and A X S mating types, respectively. Matings involving A sires and dams produced calves significantly earlier in the calving season than did matings involving S sires and dams. Matings involving S sires and dams produced calves with significantly longer gestation periods than matings of A sires and dams. Calving ease score and survival to weaning were not affected by breed of sire, breed of dam, age of dam, sex of calf, or the interaction of breed of sire X breed of dam. Percentage of live calves at 24 h indicated that straightbred S calves were significantly less viable at birth than the other four mating types.(ABSTRACT TRUNCATED AT 250 WORDS)     

Birth weight, dystocia and calf mortality in some New Zealand beef breeding herds

Calf mortality data were summarized from four experiments, including a total of 15,694 birth records over 39 herd-years. Two experiments at Waikite and Waikeria were long-term, straightbred Angus and Hereford selection trials and the other two, at Goudies and Tokanui stations, were comparisons of 11 sire breeds mated to Angus and Herefore cows. The objective of the analyses was to study the relationship between birth weight (BW) and calf mortality for both calf sexes and for different dam age or parity groups. Overall calf death rates from birth to weaning were greater (P less than .01) from 2-yr-old than from older dams at Waikite (13.4 vs 5.3%) and Waikeria (14.7 vs 5.2%). Sex differences in death rate within 2 d of birth were small for calves from older dams. Death rate of males vs females from 2-yr-old dams were 9.1 vs 3.2% (Waikite) and 17.7 vs 10.5% (Waikeria). Mature Angus dams at Goudies had 3.7% calf deaths at birth (4.9 vs 2.4% for males vs females), a further 1.8% calf deaths to weaning and 4.6% assisted births. The BW of calves at Waikite from Angus 2-yr-old vs older dams averaged, respectively, 6.8 and 6.5% of their dam's precalving live weights. Corresponding figures for Waikeria Angus were 7.8 and 6.6% and for Waikite Herefords, 7.3 and 6.9%. Quadratic regressions revealed that, on a whole-herd basis, a small increase in BW would have no effect on total mortality at Waikeria and would decrease total mortality at Waikite; regression lines were different in shape and minimum value for calves from the two dam age groups. Quadratic models also provided an adequate fit to data from Goudies and Tokanui. There was no particular threshold BW.     

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

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

Crossing beef x beef and beef x Brown Swiss: pregnancy rate, calf survival, weaning age and rate

October pregnancy rate, calf survival to weaning, weaning age, weaning rate and actual kg of calf weaned/cow exposed were determined in a 4-yr study involving 880 matings of Angus (A), Hereford (H) and Charolais (C) sires to A, H, C and Brown Swiss (BS) dams. Cows were mated in single-sire herds for 45 or 60 d under pasture conditions; heifers were bred to produce their first calf at 3 yr of age. Pregnancy rate of lactating dams was 9.4% higher (P less than .01) than for non-lactating dams. Pregnancy rates for straightbred matings were 87.5%, 80.6% and 75.4%, respectively, for A, H and C groups (P less than .05). No differences (P greater than .10) due to sire breed were found for any of the traits studied except for calf age at weaning. Calves from C sires were younger (P less than .01) at weaning than calves from H and A sires. Breed-of-dam differences (P less than .05 to P less than .01) were found for all traits studied except calf survival rate. All BS dams produced crossbred calves and had lower pregnancy and weaning rates (both P less than .01), calves were younger at weaning (P less than .05), had lower kg of calf weaned/cow exposed (P less than .05) than for beef-breed dams producing crossbred calves. Crossbred calves from BS dams were 4.9, 11.0 and 3.4 d younger (P less than .05 to P less than .01) at weaning, respectively, than crossbred calves from H, A and C dams.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of production characteristics from birth through slaughter of calves sired by Angus, Charolais or Piedmontese bulls

Birth, weaning, growth and carcass records for calves sired by Angus, Charolais or Piedmontese bulls were used to evaluate the potential contribution of Piedmontese to beef production in the U.S. Bulls were mated by AI to Hereford and crossbred cows and heifers. Calves were born during fall 1985 or spring 1986. Statistical models used to analyze the importance of sire breed used sire nested within sire breed as a random effect. Effects of sex, birth season, contemporary group, dam breed and parity were considered fixed and tested with the residual error. Piedmontese-sired calves had the longest gestation length, followed by Charolais and Angus-sired calves (287.5, 285.0 and 282.8 d, respectively). Breed of sire was not significant for birth weight, but Piedmontese- and Charolais-sired calves had longer cannon bones than Angus-sired calves. Differences were found for weaning hip height, but weaning weights, weaning muscle scores and ADG during the preweaning period were similar for calves by the three sire breeds. When fed to a similar fat thickness, Angus-sired calves required fewer days on feed, produced lighter carcasses and gained less per day than Charolais- or Piedmontese-sired calves. Piedmontese-sired calves required more days on feed than Charolais-sired calves when slaughtered at a similar subcutaneous fat thickness. Piedmontese-sired calves produced carcasses with a larger average rib eye area, higher dressing percentage and lower (more desirable) yield grade than Charolais- or Angus-sired calves. No significant sire breed differences were detected for tissue cholesterol content.     

Effect of breed of sire,breed of dam,pasture program and of their interactions on preweaning performance of crossbred beef calves

Angus (A), Hereford (H), Jersey (J), Simmental (S) and Brahman (B) bulls (202), were mated to A and H cows (855 cow-years) to produce F₁ calves. Cows were randomly assigned within age and breed to two pasture programs. The two pasture programs were expected to differ in particular with respect to the energy level offered to the cows during winter (tall fescue hay versus corn silage). Effects of genotypes, pasture program and of their interactions on preweaning traits were studied. Differences (P< 0.05) between pasture programs were found only for frame and muscle scores. Marginal means for A dams were higher (P<0.05) than those for H cows for all traits, except birth weight. Calves sired by B bulls were heavier (P<0.01) at birth than those sired by S, A and H, and J bulls. For the other traits, S-sired calves tended to have the largest estimated means, followed by calves of B bulls, then by the average of calves sired by A and H bulls and finally by J-sired offspring. Significant (P< 0.05) breed of sire × breed of dam interactions involved only extreme sire breeds. All hypotheses involving pasture program × breed of sire interactions were not significant. Muscle score was the only trait affected (P< 0.05) by a pasture × breed of dam interaction. However, its effect was only magnitudinal. Birth weight was the only trait not affected at all by the pasture program × breed of sire × breed of dam interaction. In the other traits, significant interactions reflected changes in the magnitude of the response rather than in the ranking of genotypes across pasture programs.     

Evaluation of performance characteristics in a diallel among Simmental, Limousin, Polled Hereford and Brahman beef cattle. I. Growth, hip height and pelvic size

Progeny of a diallel among Simmental, Limousin, Polled Hereford and Brahman breeds of cattle were evaluated over 5 yr for preweaning and postweaning growth, hip height and pelvic size. Calves from Brahman and Simmental dams had the highest preweaning gains and weaning weights, and those from Polled Hereford dams had the lowest (P less than .05). Differences in the availability of milk and postpartum compensatory gains in progeny of Brahman dams could have contributed to these results. However, calves from Simmental, Limousin and Polled Hereford dams had significantly greater feedlot daily gains than those from Brahman dams. Yearling hip height and pelvic area were lower for progeny of Polled Hereford dams, whereas calves from Simmental, Limousin and Brahman dams were not different for these traits. A series of linear comparisons among these four breeds using least-squares means to estimate general and specific combining ability and maternal effects found significant, negative maternal effects for Polled Hereford for preweaning gain and weaning weight. A positive maternal effect (P less than .05) for Limousin was found for feedlot gain. General combining ability and maternal estimates were significant and variable in most comparisons for yearling hip height and pelvic area. Heterosis estimates were positive and significant in all crosses with Brahman for preweaning gain, weaning weight, yearling weight, hip height and pelvic area. Significant, positive heterosis was also found in Polled Hereford crosses with Limousin and Simmental for preweaning gain, weaning weight and yearling weight.     

Lactation and calf weight traits of mature crossbred cows fed varying daily levels of metabolizable energy

Our objective was to evaluate differences in lactation traits and calf weights produced by F1 cows under varying daily metabolizable energy availability. Measures of milk yields and calf weight traits were recorded on mature F1 cows. The cows were produced from matings of Angus or Hereford dams with sires representing Angus/Hereford, Shorthorn, Galloway, Longhorn, Nellore, and Salers breeds. The cows' daily DM intakes of a diet composed of a corn silage or alfalfa silage plus corn silage were recorded from approximately 2 wk postpartum until the calves were weaned at an average age of 170 d. Milk yield measurements were recorded when the calves were approximately 14, 28, 56, 84, 112, 140, and 168 d of age. Sources of variation considered for the traits of interest included sire breed of the cow (SBC) and the covariates weaning age of the calf and daily metabolizable energy intake (DMEI) of the cow for lactation and calf weights. The linear and quadratic effects were evaluated for DMEI. The SBC x DMEI (linear) interaction was significant for total milk yield. Sire breed of cow differences (P < .05) were observed for milk yield at time of peak yield, persistency, preweaning ADG, and weaning weight. Salers- and Shorthorn-sired cows had greater (P < .05) peak yield than Galloway, Longhorn, or Nellore cross-bred cows but were not significantly different from the Hereford/Angus. Increasing DMEI linearly increased peak yield and total yield (P < .05). Preweaning ADG of calves from Nellore-sired cows was greater (P < .05) than all SBC. Preweaning ADG of calves from Galloway-sired cows was less than all SBC (P < .05). The linear effect of DMEI was heterogeneous across SBC for total yield. The pooled quadratic effect of DMEI was significant for all traits except birth weight. The DMEI for expression of maximum weaning weight was estimated to be 29 Mcal. Feed efficiency ratios for the test period were 28, 27, 30, 25, 28, 32, and 30 g calf weight:Mcal DMEI for reference and 1980s Angus/Hereford-, Shorthorn-, Galloway-, Longhorn-, Nellore-, and Salers-sired cows, respectively, at the DMEI level of 29 Mcal.     

Additive and heterosis effects on preweaning traits, maternal ability and reproduction from crossing of the Angus and brown Swiss breeds in Florida

Angus (A), Brown Swiss (S) and A X S reciprocal F1 (AS) dams were mated to A, S and AS (also reciprocal F1) sires resulting in nine breed groups of progeny with varying proportions of Angus and Brown Swiss breeding. Breed group of dam and of sire significantly influenced birth weight, preweaning daily gain, weaning weight, 205-d weight, condition score and frame size. The means for birth weight and weaning weight were 33 and 213 kg, respectively. Brown Swiss bulls sired calves with the heaviest birth and weaning weights. Calves produced by S dams likewise were heavier at birth and weaning. Pregnancy rates were influenced significantly by year, age and breed of dam and averaged 79, 95 and 92% for S, AS and A cows, respectively. Survival rate averaged 97% and was not influenced significantly by any of the effects examined. Because survival rates were similar for all breed groups, the results for weaning rate paralleled those for pregnancy rate. Genetic influences on preweaning growth traits and survival rate were partitioned into additive breed differences (B) and heterosis (H) effects for direct (d) and maternal (m) components. Pregnancy and weaning rates were examined using similar analyses except that genotype of service sire of dam replaced that of the offspring for the direct additive breed and direct heterosis components. The Bd values indicated that the Angus breed was inferior (P less than .01) to the Brown Swiss breed for all preweaning growth traits except for condition score, in which the Angus breed surpassed (P less than .01) the Brown Swiss. The Bm values also showed an advantage for the Brown Swiss breed for all preweaning growth traits. The additive maternal effect (the genotype of the females exposed), Bm, was important for pregnancy rate and weaning rate (P less than .001 and P less than .05) but not for survival rate (P greater than .10). The direct additive breed effect was not important for any reproductive trait. Direct heterosis did not affect any of the preweaning or reproduction traits; however, maternal heterosis (Hm) significantly affected all traits except birth weight, frame score and survival rate. The Hm estimates were 12.0 and 8.4 kg for weaning weight and 205-d weight, respectively. The Hm estimates for pregnancy rate, survival rate and weaning rate were 10, 2 and 13%, respectively.     

Maternal breed of sire effects on postweaning performance of first-cross heifers and production characteristics of 2-year-old heifers.

Postweaning growth rates from weaning to 18 mo, fall condition score, pregnancy rates, and production to 2 yr of age were evaluated in a study of Angus (A)-, Pinzgauer (P)-, Red Poll (R)-, Simmental (S)-, and Tarentaise (T)-sired females from Hereford dams. First-cross heifers from the different sire breeds did not differ (P greater than .10) in initial weight. During a 140-d feed test, S gained 98.6 kg, exceeding (P less than .05) gains of P, 92.3; A, 91.4; and R, 87.3 kg but not T, 94.1 kg. Red Poll-sired heifers weighed less at the end of the 140-d test (P less than .05) than the other crosses, which did not significantly differ from each other. No breed of sire differences were found in gain from 140 d to fall weight. Simmental-sired heifers weighed more (P less than .05) than A- and R-sired heifers at 18 mo. Breed of sire and year interacted to affect pregnancy rate of the yearling heifers when mated to Shorthorn sires for 45 d. Percentage of dystocia varied from a low of 26.3 and 28.9% for T- and A-sired heifers, respectively, to 54.4 and 60.8% for P- and S-sired heifers, respectively (P less than .05). Age of dam of heifers affected (P less than .05) weight at the different period end points but not gains after weaning. Age of dam also affected incidence of dystocia. Two-year-old heifers from young dams had more dystocia than heifers from older dams. Shorthorn-sired calves from 2-yr-old heifers with different sire breeds differed in birth weight (P less than .05) but not survival from birth to weaning, ADG from birth to weaning, weaning age, or weaning condition score. Average 200-d weight of calves from P-, S- and T-sired heifers exceeded those from A- and R-sired heifers by 10.7 kg, or 5.7%.