Productivity and profitability of twin births in beef cattle

Data from 1,277 single and 85 twin calvings, occurring in both spring and fall from 1980 through 1987, were used to examine the productivity and profitability associated with twin births in beef cattle. Pregnancies in pure and crossbred cattle resulted from both AI and embryo transfer. Cows and calves were confinement-housed. Cows were individually fed to specification. Calves were given ad libitum access to creep feed and those born in 1986 and 1987 were fed to slaughter. The influence of birth number of gestation length, total calf birth and weaning weights, lactation yield, and cow fed intake during both the dry and lactating periods were examined. Twin-bearing cows had their gestation length shortened by 6.4 d (2%); yielded 25.5 (59) and 186.0 kg (73%) more weight of calf at birth and weaning, respectively; had lactation yield and lactation feed intake increased by 25 and 20%, respectively; and had precalving (dry) period feed intake no different from their single-bearing counterparts (P = .12). Postweaning growth was not different for single and twin calves (P = .50); twin gain, relative to initial size, was higher. Feedlot feed intake of twins was 85% of that for singletons (P = .20). Twins were 90% of singleton live weight at slaughter and yielded 93% of singleton hot carcass weight (P = .12). Twins were slightly older and significantly leaner at slaughter. Returns less feed costs showed twin births to be associated with increased profit for cow-calf programs. Returns less feed and overhead costs were higher for twin calves than for singles in the feedlot.     

Effect of twinning on the feed intake, performance and health of dairy cows

The aim of this study was to assess the effect of bearing twins on the health and performance of dairy cows. Data from twin-bearing Holstein Friesian cows at the Langhill Dairy Research Centre between January 1990 and July 2002 were compared to single-bearing cows to determine if there was any significant difference in milk production, feed intakes, health and fertility. There were 122 twin births (from 104 different cows) in the Langhill herd, a rate of 4.7% during the study period.

The incidence of twinning was higher in high genetic merit cows (select genetic line cows) and increased with parity (r = 0.870, P < 0.01). Compared to a single-bearing cow, a twin pregnancy was associated with a shorter gestation period, an increased chance of a retained placenta after calving and a poorer body condition score post-calving. The post-calving condition score of twin-bearing cows was negatively correlated with the total weight of calves born (r = − 0.235, P < 0.05). Twin-calving cows also had significantly more dystocia, a higher chance of having a dead calf, an increased number of days from calving to their first observed heat and number of days from calving to their first service. Dystocia was positively correlated with the number of dead calves at birth (r = 0.309, P < 0.01) and with the total weight of calves born (r = 0.211, P < 0.05). Twin-bearing cows on a low-concentrate diet had an increased chance of having metritis and/or endometritis compared to single-bearing cows on the same diet. There was no significant difference in the reason for culling or the time at which cows were culled post-calving, however, twin-bearing cows on a low-concentrate diet were 3.2 times more likely to be culled than a single-bearing cow, with cows on a high-concentrate diet having equally high levels of culling. There were no significant differences between twin- and single-producing cows' mean daily feed intakes, daily milk yields, total milk yields and milk fat and protein compositions during early, mid and late lactation pre and postpartum on a low- or high-concentrate diet. The body condition and drying off period of twin pregnant cows should be managed to avoid post-calving health and performance problems.     

Induction of parturition in dairy cows with dexamethasone.

Sixty Holstein cows were paired by parity and sire, and one of each pair was allocated at random to treatment or control; 17 cows were injected with 7.5 mg/100 kg dexamethasone trioxa undecanoate 14 days before the predicted date of calving, 13 cows received the same dose five days before term and 30 cows were left untreated. The treatment significantly advanced parturition and 29 of the 30 induced cows calved within 72 hours of the injection. Induction at day 14 before term was safe for calf and dam, the calves were 3.2 kg lighter than control calves and there was a high incidence of retained placenta. Treatment for this condition resulted in increased veterinary costs of 14.50 pounds per cow exclusive of dexamethasone treatment. Treatment at this stage was also associated with low pregnancy rates in the next breeding season. Calves born after induction at five days before term were not significantly lighter than calves from control cows, the problem of retained placenta was less marked and there were no subsequent effects on fertility. There were no significant effects of induction on milk yield or milk quality up to 200 days of lactation.     

Concentration of plasma cholesterol in beef cows and calves, milk production and calf gain.

Milk yield of 59 beef cows that calved in late September through November was measured monthly in early and late lactation and biweekly during midlactation. Milk yield was estimated by milking with a machine after over-night separation of cows from calves. Concentration of plasma cholesterol of cows and calves was measured when calves averaged 44, 93, 136, and 178 d of age (SD = 17 d). Cholesterol of calves also was measured 2 wk after weaning, when they averaged 220 +/- 2.3 d of age. Cholesterol of calves was highest at second and third samplings and dropped after weaning. The estimated intake of milkfat by calves, and to a lesser extent their intake of milk, was related positively to their plasma cholesterol as they approached weaning age. The relationship was not strong enough, however, for differences among calves in concentration of plasma cholesterol to identify accurately differences in milk yield of their dams. Within breed group, age of cow, and stage of lactation, the regression coefficients of milk yield on plasma cholesterol of cows were close to zero. The concentrations of plasma cholesterol in both cows and calves were highly repeatable, with the exception of samples that were collected when calves averaged 44 d of age. Although plasma cholesterol of calves was related positively to milk yield and milkfat yield in late lactation, the former trait was not an accurate indicator of the two latter traits.     

Effects of twinning on gestation length, retained placenta, and dystocia

Constraints to maximal productivity from twinning in beef cattle include increased incidence of dystocia and retained placenta, longer postpartum interval, and lower conception rate. Incidence and cause(s) of the shorter gestation length and of the increased retained placenta and dystocia associated with twinning were evaluated for 3,370 single and 1,014 twin births produced in a population of cattle selected for natural twin births. Gestation length was shorter for twin than for single pregnancies (275.6 vs. 281.3 d, P<.01) and likely contributed to the higher incidence of retained placenta associated with twin births (27.9 vs. 1.9%; P<.01). Incidence of retained placenta was also higher in the spring (March-April) than in the fall (August-September) calving season (18.3 vs. 11.4%; P<.01). The higher incidence of dystocia with twins than with singles (46.9 vs. 20.6%, P<.01) was primarily due to abnormal presentation (37.0 vs. 4.5%, respectively) of one or both twin calves at parturition. First- (40.5%) and second- (22.7%) parity dams with a single birth had more (P<.01) dystocia than older dams (13.4%), whereas dystocia was not affected (P>.10) by parity with twin births. Because of the shorter gestation length and the increased incidence of retained placenta and(or) dystocia, achievement of increased productivity with twinning in cattle necessitates intensive management of twin-producing dams and their calves during the calving season. Management of the increased dystocia can be facilitated by preparturient diagnosis of twin pregnancies, enabling timely administration of obstetrical assistance to facilitate delivery of twin calves and to increase their neonatal survival.     

Induction of twinning in dairy or crossbred heifers by ipsilateral frozen embryo transfer

Induction of twinning by ipsilateral nonsurgical transfer of frozen two or demi-embryos was attempted in 129 virgin dairy or crossbred heifers that had been kept under a stable in our station (group-1), mountain field (group-2) and private farm (group-3) conditions. Ninety seven heifers (75%) were diagnosed pregnant by rectal palpation at 35 to 60 days of gestation; 86 heifers produced 37 sets of twins and 49 single calves. Pregnancy rate of group-1 was lower compared to those of groups-2 and -3 (63%, 88%, 78%, respectively). Abortion and mortality rates of group-3 were significantly lower (P less than 0.05) than those of groups-1 and -2 (8% and 6%, 12% and 16%, 18% and 24%). Twin calves had a lower birth weight (P less than 0.05) than singles. But there was no significant difference in weight between singles and twin calves at 270-330 days of age. Dystocia and difficult delivery were not observed in females producing twins. The incidence of retained placentas in twin calving cows (17%) was higher than that of single calving cows (2%). The interval to conceive postpartum was longer in twin calving cows (95 +/- 41 days) than in single calving cows (87 +/- 26 days). Gestation length was 5.0 days shorter for twin calving cows (P less than 0.05).     

Effects of twinning on postpartum reproductive performance in cattle selected for twin births

The effects of twinning, dystocia, retained placenta, and body weight on postpartum reproduction were evaluated for 3,370 single and 1,014 twin births. Females were bred by AI for 40 d followed by 20 or 30 d of natural service with equal numbers bred and calved in spring and fall. Percentage of dams cyclic by the end of the AI period was lower (P<.05) for dams birthing and nursing a single calf (92.4%) than for dams birthing twins and nursing zero (98.7%) or two (94.7%) calves. Whereas the interval from parturition to first estrus was shorter (P<.01) for dams birthing and nursing a single (56.9 d) than for dams birthing twins and nursing one (68.5 d) or two (69.6 d) calves, length of the interval was further reduced by dystocia in nonlactating dams of either twins or singles (type of birth x dystocia, P<.05). Ensuing pregnancy rates were also affected by type of birth and dystocia. Without dystocia, dams birthing and nursing a single calf had a higher pregnancy rate (79.2%) than dams birthing twins and nursing one (61.7%) or two (66.3%) calves, whereas the lower ensuing pregnancy rates associated with dystocia in dams of singles (71.9%) resulted in similar rates among dams of singles and twins with dystocia (type of birth x dystocia; P<.01). Having a retained placenta resulted in a lower incidence of (93.5 vs. 96.4%, with vs. without; P<.05) and a longer interval to (64.7 vs. 59.2 d; P<.01) estrus while reducing subsequent pregnancy rates (X = 9.6%) in 3 of the 7 yr evaluated (retained placenta x year, P<.01). Because all parous females were bred during the same calendrical period, the shorter gestation length for twin calves (275.6 vs. 281.3 d) resulted in a longer interval from parturition to conception for twin births, whereas means for conception date differed by only 2 d between dams of twins and singles. Furthermore, a reduction (P<.01) in the interval to conception occurred with dystocia in dams of singles (89.3 vs. 85.0 d, without vs. with dystocia) and of twins nursed by zero (116.9 vs. 83.5 d), one (100.2 vs. 92.8 d), or two (96.1 vs. 97.2 d) calves. Another detriment to fertility was the higher incidence of fetal mortality or abortions associated with twin vs. single pregnancies (12.4 vs. 3.5%; P<.01). However, despite the lower conception rates for dams of twins, the increased prolificacy provides an opportunity to increase total beef production with a twinning technology.     

Twinning in cattle: III. Effects of twinning on dystocia, reproductive traits, calf survival, calf growth and cow productivity

An evaluation of natural twinning in beef cattle revealed that cows birthing twins had shorter (P less than .01) gestation lengths, more (P less than .01) retained placentas, more (P less than .01) dystocia, more (P less than .01) days to estrus, lower (P less than .01) conception rates and more (P less than .01) days to pregnancy than cows birthing singles. Days to estrus, conception rate and days to pregnancy were not affected by number of calves reared (1 vs 2) in cows birthing twins. Survival at birth was greater (P less than .01) for single- than for twin-born calves, but twins and singles did not differ (P greater than .05) in postnatal survival. When dystocia was experienced, calf survival at birth was 95% vs 73% for singles vs twins compared with 99% vs 92% when no dystocia was experienced. Calves born twins were lighter (P less than .01) at birth, 100 d and 200 d, but twins and singles did not differ in postweaning gains. Total calf weights at 100 d per cow calving were 12% greater (P less than .01) in cows birthing twins vs singles when twin calves reared by foster dams were excluded. The potential increase in cow productivity for total calf weight at 100 d is 40% if calf survival rates of twins with dystocia relative to survival rates of twins without dystocia were comparable to survival rates of singles with and without dystocia, and if cows birthing twins were fed and managed to obtain conception rates equal to those of cows birthing singles. Identification of cows gestating twins to provide for their higher prepartum nutritive requirements and calving assistance at parturition is necessary to make twinning in cattle an economically viable technology.     

一例荷斯坦奶牛双胎难产的处置与护理

奶牛的双胎难产不仅会导致犊牛窒息死亡,还可能会引起母牛的死亡.临床上对难产奶牛实施助产时,若操作不当,引起产道拉伤还会引发后续的生产性疾病,影响母牛的生产性能.为了在临床上解决奶牛双胎难产的问题,实验阐述了1例双胎犊牛同时为倒生的难产奶牛的助产处置和产后护理.结果 表明助产处置后,成功产下2头公犊牛,均存活;经过产后护...     

Effect of twin birth calvings on milk production, reproductive performance, and survival of lactating cows

OBJECTIVE: To evaluate effect of twin birth calvings on milk production, reproductive performance, and survival of lactating cows. DESIGN: Retrospective observational cohort study. ANIMALS: 33,868 cows from 20 farms. PROCEDURES: Data on age at calving for primiparous cows and mature equivalent milk yield for multiparous cows, assistance at calving, stillbirths, twin births, gestation duration, pregnancy at the end of the data collection period, and culling-death for all cows were extracted from farm computer records and used for statistical analysis. RESULTS: Prevalence of twin parturitions was 1.3% (159/12,050) and 6.5% (1,410/21,818) for primiparous and multiparous cows, respectively. Primiparous and multiparous cows with singletons produced more milk than cows with live twins or at least 1 dead twin (primiparous, 33.1 vs 31.9 vs 31.2; multiparous, 36.5 vs 35.7 vs 35.0). Multiparous cows with dead twins produced less milk than cows with live twins. Compared with dams with singleton birth, cows with twins were 0.78 times as likely to conceive and 1.42 times as likely to die or be culled. Cows with dead twins also had increased time to conception, compared with live twins. CONCLUSIONS AND CLINICAL RELEVANCE: Twin birth was associated with decreased survival, milk production, and reproductive performance. Having at least 1 dead twin was even more detrimental than having live twins and resulted in decreased milk production and reproductive performance of lactating cows.     

Age of cow and age of dam effects on milk production of Hereford cows

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.     

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.     

Risk of abortion associated with Neospora caninum during different lactations and evidence of congenital transmission in dairy cows

OBJECTIVE: To examine the relationship between exposure to Neospora caninum and abortion in dairy cows during their first, second, third, and fourth or later lactations and to establish the main mode of transmission in female calves from birth until their first pregnancy was terminated by abortion or parturition. DESIGN: Prospective observational study. ANIMALS: 460 Holstein cows and 79 female calves. PROCEDURE: Cows were classified as seropositive or seronegative to N caninum within 7 days after calving; incidence of abortion was compared between groups during different lactations. Blood samples were collected from female calves before ingestion of colostrum and every 6 months until their first pregnancy was terminated by abortion or parturition; number of seropositive calves was compared between seropositive and seronegative dams. RESULTS: During the first pregnancy of their second lactation, risk of abortion for seropositive cows was 2.8 times that of seronegative cows. Among 10 calves born to seropositive cows, 4 were classified as seropositive at birth and thereafter. Among 69 calves born to seronegative cows, all were classified as seronegative at birth; 67 calves remained seronegative thereafter. CONCLUSIONS AND CLINICAL RELEVANCE: Exposure to N caninum alone was not significantly associated with abortion in cows during the first, third, and fourth or later lactations. Seropositive cows that have aborted previously may have subsequent abortions attributable to N caninum. Congenital infection was the main mode of N caninum transmission in a cohort of female calves.     

Risk factors for abomasal displacement in dairy cows.

OBJECTIVE: To determine whether various periparturient events or 305-day milk production during the previous lactation period were associated with abomasal displacement in dairy cows. DESIGN: Retrospective, case-control study. ANIMALS: 75 pairs of case and control cows from 3 university-owned and 3 commercial dairy herds. PROCEDURE: Cows with abomasal displacement were matched with control cows on the basis of herd of origin, breed, age, and calving date. Frequency of specific periparturient events during the period from 2 weeks prior to parturition to diagnosis of abomasal displacement, as well as milk production during the preceding lactation period, were compared between case and control cows. RESULTS: Multivariate analyses indicated that case cows were significantly more likely to have had retained placenta, ketosis, a stillborn calf, metritis, twins, or parturient paresis than were control cows. Dystocia, mastitis, and milk production during the previous lactation period were not associated with abomasal displacement. CLINICAL IMPLICATIONS: Results indicated that a variety of periparturient events were associated with development of abomasal displacement among dairy cows.     

Changes of vitamin E status of periparturient dairy cows and newborn calves

Eleven primiparous Holstein Friesian and their crossbred calves (F1, Japanese Black cattle × Holstein Friesian) and 10 multiparous Holstein Friesian and their Holstein Friesian calves were used to evaluate vitamin E status in periparturient period. Plasma α‐tocopherol (α‐toc) concentrations of the multiparous cows were significantly higher than those of the primiparous cows from 60 days before expected calving to 90 days of lactation (P < 0.05). The multiparous cows had a further decrease in the concentrations of α‐toc and total lipid in plasma to the calving than the primiparous cows. Colostrum α‐toc concentrations in multiparous cows were significantly higher than those of the primiparous cows (P < 0.05). Plasma α‐toc concentrations of calves borne by the multiparous cows were significantly higher than those of the primiparous cows at 5 days of age (P < 0.05). Plasma α‐toc concentrations of calves were highest at 5 and 15 days of age in the calves borne by the multiparous and primiparous cows, respectively, and decreased thereafter till 90 days of age. The higher vitamin E status of multiparous cows over primiparous cows might have reflected nutritional composition in the rations. Their calves afforded higher plasma α‐toc levels after birth because of more α‐toc transfer via placenta and more α‐toc secretion in the colostrums thereafter. Plasma α‐toc concentrations of the calves might have decreased as the calves became dependent upon the solid feed of low vitamin E content.     

In utero transmission of bovine leukemia virus

In an initial study, 18 calves born to cows persistently infected with bovine leukemia virus (BLV) were tested for infective virus and antibodies at birth, and no infected or seropositive animals were found. Four of these calves were maintained in quarters where infected animals were housed, and 3 of the 4 subsequently became infected. These were probably contact infections acquired during, or at some time after, birth. The remaining 14 calves were kept in isolation pens in a building housing no infected cattle. None of this group was found to be BLV infected during 1 year of observation. In further studies, 15 pregnant cows inoculated with BLV became infected. One abortion, considered to be unrelated to the BLV inoculation, occurred 38 days later. The remaining 14 cows gave birth to 1 dead and 14 live calves. The dead calf and its live twin were seropositive for BLV at birth, indicating that they had been infected in utero. The remaining 13 calves were negative for BLV antibodies at birth and remained so during 1 year of observation.     

Twins rate in the black-and-white cattle population in Lithuania

Obtaining the maximal number of calves from each cow according to its natural genetic reproduction ability is the main condition of intensification of reproduction and increase of milk production. Twins rate in the black-and-white cattle population in Lithuania is 2.4%. Cows whose mothers have calved twins at least 1 time during reproductive life have twins in 5.6% of all calvings, the others--in 1.9%. Twins rate in separate bulls daughters range from 1% to 6.1%. Twins rate in cows range from 0.4% to 5% by separate bulls-getters. Productivity of 305 days lactation after having twins is better (551.2+/-68.1 kg of milk, 18.4 +/-2.9 kg of fat and 21.5+/-2.4 kg of protein, P < 0.001). The rate of twin births increases when lactation is increased. The influence of lactation on rate of twin births is 0.6% in total dispersion (P < 0.001). The influence of calving season on twins rate is statistically insignificant but the parts of twins by calving seasons are distributed differently.     

影响荷斯坦牛产奶量差的因素分析

产奶量差是奶牛个体同一胎次前后2个泌乳月产奶量的差值,可准确反映产奶量变化情况。为探究影响荷斯坦牛产奶量差的因素,本研究收集整理了江苏省某大型奶牛场2015-2018年55 193头次荷斯坦牛生产性能测定记录,并利用最小二乘法分析胎次、测定年度、产犊季节、泌乳月4个因素对荷斯坦牛产奶量差的影响。结果显示:胎次、测定年度、产犊季节、泌乳月及其交互作用对产奶量和产奶量差均有极显著影响(P<0.01)。其中,不同胎次、测定年度和产犊季节的荷斯坦牛总产奶量在第2个泌乳月增加最快,产奶量差为8.79kg;头胎第6泌乳月、二胎第7泌乳月和三胎及以上第6泌乳月产奶量下降最大,产奶量差分别为-2.86kg、-4.59kg和-6.13kg;2015-2018年4个测定年度中,第10、第6、第7、第6泌乳月产奶量降低最大,产奶量差分别为-2.26kg、-4.98kg、-4.44kg和-3.56kg;春季产犊的荷斯坦牛第4泌乳月、夏季产犊的荷斯坦牛第12泌乳月、秋季产犊的荷斯坦牛第9泌乳月、冬季产犊的荷斯坦牛第6或第7泌乳月产奶量下降最大,产奶量差分别是-4.34kg、-4.71kg、-5.36kg和-5.40kg。此外,产奶量差与泌乳持续力呈极显著正相关(P<0.01),与产犊间隔呈显著正相关(P<0.05),与泌乳天数、高峰奶、乳脂率、蛋白率、305d产奶量呈极显著负相关(P<0.01)。因此,产奶量差作为衡量奶牛产奶量变化的指标之一,可为牧场进行科学饲养管理提供参考。     

Increased calf production in cattle selected for twin ovulations

The effects of increasing fetal numbers and their distribution between the left and right uterine horns on calf survival, calf BW at birth and weaning, gestation length, dystocia, and calf sex ratio were evaluated for single (n = 1,587), twin (n = 2,440), and triplet calves (n = 147) born to primiparous and multiparous females in the Twinner population at the US Meat Animal Research Center between 1994 and 2004. Cattle were distributed equally between the spring and fall breeding seasons. Fetal number and distribution in utero were determined by real-time ultrasonography at 40 to 70 d postbreeding. For cows and heifers combined, number of calves per parturition increased from 1.34 in 1994 to 1.56 in 2004. Gestation length was 6.8 d shorter (P < 0.01) for twins compared with singles (277.5 +/- 0.2 vs. 284.3 +/- 0.2 d) and 12.7 d shorter for triplets (271.6 +/- 0.8 d). Survival and BW of individual calves at birth decreased (P < 0.01) but total calf BW per dam increased (P < 0.01) as fetal number increased from single to triplet births. Twins resulting from bilateral twin ovulations had increased (P < 0.01) survival and BW at birth, a longer (P < 0.01) gestation length, and less (P < 0.01) dystocia than twins resulting from unilateral twin ovulations. Calf survival and BW at birth were 97.2 +/- 0.3% and 48.0 +/- 0.1 kg for singles, 92.0 +/- 0.4% and 39.0 +/- 0.2 kg for bilateral twins, 83.2 +/- 0.4% and 36.7 +/- 0.2 kg for unilateral twins, 73.8 +/- 1.4% and 30.6 +/- 0.7 kg for bilateral triplets, and 51.9 +/- 3.2% and 31.7 +/- 1.6 kg for unilateral triplets. Birth weight of single calves increased by 0.51 kg/d for each additional day of gestation length vs. 0.38 kg/d for individual twins. Calf BW at birth increased (P < 0.01) with age of dam from 2 to 4 yr. Twin and triplet births had a greater (P < 0.01) incidence of dystocia than single births. The ratio of male:female calves (0.52:0.48) at birth was not affected by type of birth. Postnatal calf survival was similar for all 3 types of birth. Total progeny BW at weaning for single, twin, and triplet births was 217.7 +/- 2.5, 328.3 +/- 3.2, and 378.4 +/- 15.0 kg, respectively (P < 0.01). Although most bovine females have the uterine capacity to gestate twin calves, decreased survival and BW of unilateral twins and of all triplets indicate that their growth and development may have been compromised by uterine crowding.