共查询到20条相似文献，搜索用时 614 毫秒
1.
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. 相似文献
2.
Measures of maternal productivity and reproduction of Hereford (HH), Angus-Hereford (AH), 25% Simmental-75% Hereford (1S3H), 50% Simmental-50% Hereford (1S1H) and 75% Simmental-25% Hereford (3S1H) dams were studied. Half of each dam breed group was bred to Tartentaise and half to Charolais sires to produce 706 calves at weaning from 930 exposures to breeding in a Montana range environment. Data were analyzed according to a model that included the fixed effects of year, dam breed group, dam age, calf sex, calf sire breed, plus appropriate two-way interactions, linear partial regression on calf birth date and random effects of sire within dam breed group (maternal grandsire of the calf) and sire within calf sire breed. Calf sex interacted with calf sire breed for several traits, but interactions were due to changes of magnitude of differences between sexes. There were no significant interactions of dam breed group with other main effects for calf growth traits, except for the interaction with calf sire breed for some calf growth traits. This interaction was due to a change in magnitude; it suggested that larger sire breeds should be matched to larger dam breeds with greater potential for milk production. The only significant interaction for traits that included reproduction of the dam was dam breed group X age of dam. Ranking of dam breed groups depended on age at measurement. Differences among dam breed groups were significant for most traits. Calf weaning weights for HH, AH, 1S3H, 1S1H and 3S1H dams were 211, 223, 227, 237 and 243 kg, respectively; calf weaning weights per cow exposed were 157, 163, 179, 189 and 169 kg; calf weaning weights per unit of dam weight were .40, .41, .43, .44 and .42, respectively. Thus, dam breed groups that weaned the largest calves were not necessarily the most productive under Montana range conditions. 相似文献
3.
Maternal performance of 134 Hereford (H), Brangus (B), and reciprocal crossbred (H x B and B x H) cows from 2 to 7 yr of age was evaluated under semidesert conditions in this study. Calves produced by 2- and 3-yr-old cows were sired by Brangus and Hereford bulls. Calves produced by 4- to 7-yr-old cows were sired by Charolais bulls. Breed of sire and breed of dam of cow affected kilograms of weaning weight, 205-d weight, weaning weight as a percentage of cow weight, and 205-d weight as a percentage of cow weight produced annually. Brangus (either as sire or dam of cow) was superior to Hereford in all cases. Observed maternal heterosis on 2- to 3-yr-old cows was 23.0, 20.1, 30.0, 29.1, 23.9, and 23.0% for calf birth date, weaning percentage, weaning weight per year, 205-d weight per year, weaning weight as a percentage of cow weight per year, and 205-d weight as a percentage of cow weight per year, respectively (P less than .01). Observed maternal heterosis from mature cows was 19.8, 12.8, 21.0, 18.7, 17.4, and 15.4% for calf birth date, weaning percentage, weaning weight per year, 205-d weight per year, weaning weight as a percentage of cow weight per year, and 205-d weight as a percentage of cow weight per year, respectively (P less than .01). Results indicate large heterotic effects on annual cow productivity and an adaptive advantage for cows with Brangus sires and(or) dams under semidesert conditions. 相似文献
4.
R E Sacco J F Baker T C Cartwright C R Long J O Sanders 《Journal of animal science》1989,67(8):1972-1979
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) 相似文献
5.
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. 相似文献
6.
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. 相似文献
7.
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. 相似文献
8.
Data in this experiment consisted of 418 lactation records, and weaning and birth weight records from 600 crossbred calves. The traits evaluated included birth weight, weaning weight, weaning weight per cow exposed, weaning weight per weight of cow, weaning weight per weight of cow exposed, and predicted milk yield. Angus, Brangus, and Gelbvieh sires were mated to purebred Hereford cows. Yearling and 2-yr-old Angus-Hereford, Brangus-Hereford, and Gelbvieh-Hereford daughters then were bred to Polled Hereford bulls (Data Set 2). Later-parity Angus-Hereford, Brangus-Hereford, and Gelbvieh-Hereford daughters were mated to Salers or Simmental sires (Data Set 3). Differences between Gelbvieh- and Brangus-sired calves or Gelbvieh-Hereford and Brangus-Hereford daughters were never significant for weaning weight, birth weight, or milk yield. Angus crosses had the lowest weaning weight, birth weight, and milk yield, but the highest kilograms of calf weaned per cow exposed in all data sets. Angus-Hereford and Brangus-Hereford dams had higher weaning weight per weight of cow exposed than Gelbvieh-Hereford dams (P < .01) in Data Set 3. There were no other significant differences related to cow weight. 相似文献
9.
Milk production in Hereford cows was studied utilizing 2,487 lactation records on 926 cows. Data were collected over 17 yr (1968 to 1984) from two related herds. Estimates of daily milk yield were obtained at bimonthly intervals by the calf suckling technique. The sum of three monthly measures (TMY), a predicted sum of seven monthly observations (PMY) and 205-d weight of the calf were studied. Year, age of cow, age of dam at cow's birth and calf birth weight affected (P less than .05) all traits. Birth weight affected all measures of milk, with heavier calves obtaining more milk. Age of cow effects were significantly curvilinear, with PMY and TMY increasing for cows from 2 to 5 yr of age, but not differing for cows 6 yr and older. Age of cow effects on 205-d weight were similar to those for milk. As age of cow increased from 2 to 4 yr, 205-d calf weight increased. A leveling off in 205-d weight was observed for calves of cows 5 yr and older. Effects of age of dam of cow also were significant for all milk traits studied. As age of dam increased, PMY and TMY decreased. Highest milk yields were for cows born to and reared by 2-yr-old dams, intermediate milk yields for those by 3- and 4-yr-old dams and lowest yields by daughters of mature dams. Cows born to and reared by older dams produced less milk and weaned lighter calves. There were no interactions between age of cow and age of dam. This suggests a lasting detrimental effect of older cows on lactation yield of daughters. Thus, it appears that age of dam should be considered in evaluation of cow performance. 相似文献
10.
Reproductive traits and preweaning growth of progeny from young Hereford, Red Poll, Hereford X Red Poll, Red Poll X Hereford, Angus X Hereford, Angus X Charolais, Brahman X Hereford and Brahman X Angus dams were evaluated. First-calf heifers were mated with Red Angus bulls; Santa Gertrudis sires were used for each cow's second and third breeding season. Herefords, Red Polls and Hereford-Red Poll crosses were below average in percentage of calves weaned, whereas Angus-sired and Brahman-sired dams exceeded the overall mean. Angus X Charolais (P less than .10), Brahman X Hereford (P less than .01) and Brahman X Angus (P less than .10) dams weaned a higher percentage of calves than straightbred Herefords. None of these breed types differed from young Angus X Hereford females in reproductive performance. Angus X Charolais calves ranked highest in 180-d calf weight, exceeding progeny from both Hereford (P less than .01) and Angus X Hereford (P less than .10) dams. Brahman X Hereford dams weaned heavier (P less than .05) calves than Herefords, but their progeny did not differ at weaning from those reared by Angus X Herefords. Calves from Brahman X Angus dams weighed 12.7 kg less (P less than .01) than Angus X Hereford progeny. Analysis of the Hereford-Red Poll diallel showed evidence of (P less than .10) maternal heterosis in 180-d calf weight.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
11.
Mature dams representing Hereford, Red Poll, F1 Hereford x Red Poll, F1 Red Poll x Hereford, F1 Angus x Hereford, F1 Angus x Charolais, F1 Brahman x Hereford and F1 Brahman x Angus breed types were evaluated. All cows were bred to Limousin sires to produce two-way or three-way-cross progeny. Mature Brahman x Hereford dams produced a higher (P less than .05) percentage of live calves than Herefords, but dam breed differences in percentage of calves weaned relative to the number of cows exposed for mating were not statistically significant. Progeny of Angus x Charolais and Red Poll dams were outstanding in weaning weight, but Hereford and Brahman-cross calves were below average. Planned comparisons showed that Angus x Charolais calves were heavier (P less than .01) at weaning than Hereford (23.0 +/- 3.8 kg) or Angus x Hereford (9.6 +/- 3.2 kg) progeny. Mature Angus x Hereford mothers weaned heavier calves than did Brahman x Herefords (7.4 +/- 3.2 kg, P less than .05) or Brahman x Angus (10.9 +/- 3.0 kg, P less than .01). Analysis of the Hereford-Red Poll diallel showed evidence of maternal heterosis in calf weaning weight (4.0 +/- 2.6 kg, P less than .05), but there was no difference in the percentage of calves weaned by crossbred vs straightbred dams.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
12.
From 1979 through 1987, British breed and crossbred cows were mated to Simmental, Pinzgauer or Tarentaise bulls or to Hereford-Angus crossbred bulls. Beginning in 1982, continental European crossbred females also entered the herd, to be mated for first calving to Hereford-Angus or Angus bulls and as cows to continental European or Hereford-Angus bulls. In progeny of British breed and crossbred cows, dam breed effects on birth and weaning weight were not important, but continental European crossbred calves were heavier than British crossbred contemporaries at birth and weaning. Pinzgauer- and Simmental-sired calves were heavier at birth than Tarentaise crosses, but calves sired by each of the continental breeds had similar weaning weights. Maternal heterosis was greater than direct heterosis effects on weaning weight (8% vs 5%), but only direct heterosis (13%) influenced birth weight. Within progeny of continental European crossbred cows, calves with a Tarentaise maternal grandsire were lighter at birth, with no significant difference among other maternal grandsire breeds. Maternal breed effects on weaning weight were not significant. Nevertheless, in contemporary years, continental European crossbred cows reared calves that were 10% heavier than calves reared by British crossbred cows. Pacific Northwestern cattle producers could achieve substantial increases in weaning weight from introducing inheritance from continental European dual-purpose breeds into cow herds and calf crops of British ancestry. 相似文献
13.
Reproductive and preweaning data on 190 Angus (A x A), Brahman (B x B), and reciprocal-cross cows (A x B and B x A) and 434 two- and three-breed-cross calves managed on common bermudagrass (BG), endophyte-infected tall fescue (E+), or a combination of both forages (ROT) were used to evaluate the interaction of forage type with individual and maternal heterosis and maternal and grandmaternal breed effects. Cows were born from 1988 to 1991, and calves sired by 13 Polled Hereford bulls were born from 1995 to 1997. Heterosis for calving rate was larger on E+ than on BG or ROT (P < .05), whereas maternal effects were larger on BG than on ROT (P < .10). Maternal heterosis for birth weight was negative on BG (P < .11) but positive on E+ and ROT (P < .10). Grandmaternal effects were evident on BG (P < .10) and E+ (P < .01) but not on ROT. Forage effects were generally substantial for 205-d weight, calf weaning hip height, and calf weaning weight:height ratio; BG was highest, ROT was intermediate, and E+ was lowest. Maternal heterosis for these traits was generally greater on E+ than on BG (P < .10). Grandmaternal effects for 205-d weight, hip height, and weight:height ratio were not important on any forage. Heterosis for weaning weight per cow exposed was substantial on all forages (P < .01) and was significantly greater on E+ (P < .01) than on BG or ROT, but maternal effects were not significant. Thus, we observed more advantage to Brahman-cross cows over purebreds on E+ than on BG. We also observed that moving cows and calves from E+ to BG in the summer will alleviate some, but not all, of the deleterious effects of E+ on calf growth, although it may be more beneficial for reproductive traits in purebred cows. 相似文献
14.
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. 相似文献
15.
Productivity of 2-yr-old crossbred cows containing various proportions (0, 1/4 or 1/2) of Brahman breeding was evaluated using 203 spring-calving and 171 fall-calving heifers over a 3-yr period. All heifers were mated to Limousin sires. Percentage of cows exposed to breeding that weaned a calf was the only trait for which a significant crossbred cow group x season of calving interaction was found. Preweaning ADG and age-adjusted weaning weight increased as proportion Brahman breeding increased. Age-adjusted weaning weight was similar for the two groups because spring-born calves were weaned at an average age of 205 d and fall-born calves were weaned at an average age of 240 d. For weaning condition scores, an interaction between dam breed and proportion Brahman was detected; scores tended to be greater for calves out of 1/2 Hereford dams than for those out of 1/2 Angus dams, and this difference increased as proportion Brahman increased. Weaning conformation scores were similar for all calves. Age-adjusted weaning hip height increased as proportion Brahman breeding increased. Based on numbers of weaned calves, spring calving was more advantageous than fall calving. Averaged across both calving seasons, weaning weight tended to increase as proportion Brahman increased. 相似文献
16.
Data were analyzed to estimate the effects of heterosis and breed on a series of maternal and individual traits. Crossbred cows were Boran X Ankole and Boran X Zebu; straight-bred cows were Ankole, Boran and Small East African Zebu (Zebu). Cows of all breed groups were mated to Friesian, Brown Swiss and Simmental sires to produce crossbred progeny. While not generally significant, the average effects of heterosis of both crosses for the traits analyzed were: calf crop born, 7.0%; preweaning viability, 7.2%; overall viability, 7.3%; birth weight, 6.0%; weaning weight, 5.4%; 12-mo weight, 4.2%; 18-mo weight, 3.7%; 24-mo weight, 3.6%; calf weight weaned per cow exposed to breeding (cow productivity index), 24.5%; cow parturition weight, 3.5%; cow weaning weight, 4.2% and cow mean weight, 4.0%. Boran cows weaned 31.8 kg (48.0%) more (P less than .05) calf weight per cow exposed to breeding than Ankole cows. Boran cows were generally superior to Zebu cows in progeny weights at all ages (P less than .01). Boran cows weaned 34.5 kg (54.3%) more (P less than .05) calf weight per cow exposed to breeding than Zebu cows. Boran cows weighed an average of 70.8 kg more (P less than .01) than Zebu cows. Although progeny of Ankole dams were heavier (P less than .05) than the progeny of Zebu dams at all ages, the two breeds did not differ (P greater than .05) in calf weight weaned per cow exposed to breeding. Mean weight of Ankole cows was 75.8 kg heavier (P less than .01) than mean weight of Zebu cows. 相似文献
17.
Productivity of 3-, 4-, and 5-yr-old crossbred cows containing various proportions (0, 1/4, or 1/2) of Brahman breeding out of Angus or Hereford dams was evaluated using 489 spring-calving and 427 fall-calving records collected over a 4-yr period. Cows were bred to Limousin sires for the first 3 yr and to Limousin and Salers sires the 4th yr. Interactions between crossbred cow group and season of calving were not significant. Percentage of cows exposed to breeding that weaned a calf increased (P less than .01) as proportion Brahman breeding increased, was higher (P less than .01) for cows out of Angus dams than for cows out of Hereford dams, and was higher (P less than .01) for spring-calving cows. As the proportion Brahman increased, the percentage requiring assistance at birth decreased, and cows out of Angus dams required less (P less than .05) assistance than those out of Hereford dams. Preweaning ADG, adjusted weaning weight, weaning conformation, weaning condition, and adjusted weaning hip height increased a proportion Brahman breeding increased. Spring-born calves gained .12 kg/d faster (P less than .01) than fall-born calves. However, weight at weaning was similar for the two groups; spring-born calves were weaned at an average age of 205 d, and fall-born calves were weaned at an average age of 240 d. Fall-calving cows were heavier (P less than .05) than spring-calving cows, and 0 and 1/2 Brahman cows were heavier (P less than .01) than 1/4 Brahman cows. These data indicate that Brahman-cross dams can be used to improve reproductive rate and increase preweaning growth rate, and thus weaning weight.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
18.
Birth weight, preweaning gain and weaning weight (adjusted 180-d weight) data, collected at McGregor, Texas, were analyzed for genetic differences. Breedtypes represented in the data were Brahman, Hereford and various Brahman-Hereford crosses. Preweaning gain was calculated as adjusted 180-d weight less birth weight. All statistical models included effects of dam age, year, season and sex. Analyses were performed using a breedtype model and a regression model that redefined breedtype as direct additive, direct heterotic, maternal additive and maternal heterotic effects. Brahman dams produced calves with lightest birth weights. Brahman-sired calves were heaviest at birth compared with those by other sire breedtypes. The estimated Brahman direct additive effect on birth weight was 4.6 kg greater than Hereford. The Brahman maternal additive effect was 7.5 kg less than Hereford. Direct and maternal heterotic effects on birth weight were 2.2 and .6 kg, respectively. Calves from F1 dams had larger preweaning gains than those of the other breedtypes. The Brahman direct additive effect on preweaning gain was 17.7 kg less than Hereford and the Brahman maternal additive effect was 20 kg greater than Hereford. Direct and maternal heterotic effects on preweaning gain were 19.6 and 19.5 kg, respectively. Results of weaning weight analyses were similar to preweaning gain analyses. The largest effects on weaning weight were direct and maternal heterosis, which were 21.6 and 19.8 kg, respectively. 相似文献
19.
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) 相似文献
20.
Interrelationships among milk production, dam-calf feed efficiency to weaning, and other biological traits were evaluated on 411 first-calf heifers and their calves. Individual feed intakes were measured in a drylot environment for a 1-yr period until weaning of the first calf. Heifer breed types included crossbred Angus-Hereford, Simmental-Hereford, and Tarentaise-Hereford produced in two-breed rotational crossbreeding systems, F1 Salers-Hereford and straightbred Hereford. Production efficiency was defined as cumulative feed ME consumed by the dam-calf pair during the year divided by calf weaning weight. Milk production potential seemed to be unrelated to cow size, adjusted for breed-group effects. Lactational feed energy was increased for dams of increased milk production potential but not enough to offset the increased production of calf weaning weight in terms of production efficiency. Results indicated that increased levels of milk production of heifers were associated with improved production efficiency to weaning. However, the incremental improvement in efficiency per unit of increased milk was less for each additional unit of milk, within the range evaluated. These results are applicable to first-calf heifers that have not yet reached peak age for maximum milk production. 相似文献