HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Riley, D. G. Articles by Olson, T. A. Search for Related Content PubMed PubMed Citation Articles by Riley, D. G. Articles by Olson, T. A.

Evaluation of birth and weaning traits of Romosinuano calves as purebreds and crosses with Brahman and Angus^1,2

D. G. Riley^,3, C. C. Chase, Jr., S. W. Coleman and T. A. Olson^*

ARS, Subtropical Agricultural Research Station, Brooksville 34601; and ^* Department of Animal Sciences, University of Florida, Gainesville 32611

	Abstract

Top Abstract INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION IMPLICATIONS LITERATURE CITED

 
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.

Key Words: beef cattle • crossbreeding • heterosis • Romosinuano • weaning

	INTRODUCTION

Top Abstract INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION IMPLICATIONS LITERATURE CITED

 
Much of the available forage in the United States is in areas close to the Gulf of Mexico, and thus a large part of the US cow herd is located in this area (Chase, 2002). In part due to excellent adaptation to demanding conditions, Brahman-cross cows are very common across the southeastern United States (Turner, 1980). However, several Brahman performance issues need improvement, and strategies should include consideration of breeds that could complement, in crossbreeding programs, or serve as alternatives to the Brahman (Cartwright, 1980).

For almost all traits in beef production, Brahman x Bos taurus crossbreds express greater heterosis than Bos taurus crossbreds (Cartwright, 1980; Franke, 1980; Franke et al., 2001). Some Bos taurus breeds of cattle have shown adaptation to the challenging conditions in the world’s tropics and subtropics (Thrift and Thrift, 2005). These include Criollo breeds from Central and South America and the Caribbean Islands, such as Romosinuano (Rouse, 1977). Ancestors of Romosinuano were isolated in a valley in Colombia, and the breed acclimated to the tropics over several centuries.

Romosinuano cows and their crosses have the reputation in South America for superior fertility, especially when crossed with Bos indicus breeds (Payne, 1970; Derr et al., 1995; Martinez-Correal, 1995). Characterization of Romosinuano as purebreds and as crosses with predominant US breeds is useful for understanding the adaptation mechanisms in cattle, for development of cow adaptation strategies for US Gulf Coast cow-calf producers, for identification of superior cross-breeding options, and as a part of a conservation strategy for a breed with declining numbers (FAO, 1993).

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.

	MATERIALS AND METHODS

Top Abstract INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION IMPLICATIONS LITERATURE CITED

 
All management and procedures involving cattle were approved by the USDA-ARS Subtropical Agricultural Research Station (STARS) Institutional Animal Care and Use Committee.

Cattle
Romosinuano.
Romosinuano cattle were imported as embryos from a herd at the Centro Agronómico Tropical de Investigación y Enseñanza (CATIE) in Turrialba, Costa Rica, and from purebred breeders in Venezuela. Embryos and semen from CATIE were imported into the United States by the University of Missouri, in cooperation with the University of Florida and the USDA-ARS STARS.

Foundation animals of the CATIE herd were obtained from North Carolina State College in the 1950s. The North Carolina State herd was developed by importing semen from Colombia in 1948 and 1949 and was subsequently disbanded in the late 1950s (de Alba, 1984). The CATIE herd was maintained as a small, closed herd for many years, and the cattle that produced the imported embryos were the result of a grading-up program (from Zebu and crossbred cattle). In the mid 1990s, the CATIE herd of Romosinuano was dispersed.

The Venezuelan importation in 1996 included only purebred embryos of Colombian origin; parents (12 sires and 22 dams) were selected to produce embryos that would be representative of the cattle and bloodlines within the breed at the time. It seems that all of these cattle plus a small group in Brazil can trace pedigrees to a herd in Turipaná, Colombia (Elzo et al., 1998).

Costa Rican embryos were transferred into recipient cows, and the resultant calves were born in 1991 and 1993. The Venezuelan embryos were transferred into recipient cows, and the resultant calves were born in 1997. Romosinuano cows were exposed to Romosinuano bulls (natural matings) each year from 1992 through 2000. Beginning in 1998, all bulls used were embryos from the Venezuelan importation. At the time at which the current project was initiated, approximately 200 Romosinuano cows were available.

Brahman.
Approximately 180 Brahman cows were in the STARS herd at the beginning of this project. The station herd was begun with a small number of cows and a bull in the late 1940s. Some herd bulls have been raised in the herd, but most have been borrowed or purchased. Approximately once each decade, females have been purchased from various herds. Many prominent Brahman bloodlines are present in this herd.

Angus.
Ancestors of the STARS Angus herd were obtained in the early 1950s from Florida herds, primarily from other Florida research facilities. A number of cattle were obtained from a research facility in Virginia. Some herd bulls have been raised in the herd. Bulls and semen from the Wye Plantation at Wye Mill, MD, were regularly used until the mid to late 1970s. For a brief time in the early 1990s, semen from modern Wye Plantation bulls was again used. At the beginning of this project, there were approximately 130 Angus cows.

Bulls.
A total of 42 bulls sired calves in this project, for an average of 31.8 calves per bull. Romosinuano bulls (n = 16) were the result of embryo transfer from the Venezuelan importation. Brahman bulls (n = 12) were all from outside the STARS herd, primarily from Florida breeders. Of the 14 Angus bulls used, 6 were born and raised in the research herd; the remaining 8 were obtained from Florida and Georgia breeders.

Breeding Design and Procedures
Purebred Romosinuano, Brahman, and Angus cows were randomly assigned to each of the 3 management units comprising STARS (the greatest distance is about 10 km), and subsequently to breeding herds of 25 to 30 cows (6 herds at each location, each herd consisting of cows of all 3 breeds). Purebred bulls of each breed were randomly assigned to the single-sire breeding herds. After the first project year, 1 or more bulls were again used but were always placed with different cows at a different location.

Each year, the 90-d breeding season began on or near March 20. Each year, cows were exposed to a different breed of bull. In the first year, only Angus bulls from outside sources were used. In all other years, equal numbers of bulls from the 2 sources were used. All cows with calves in the project were 3 yr old or older. The mating design produced 9 breed groups of calves (the first letter of a pair indicates the breed of sire and the second indicates the breed of dam of calves in the group; R = Romosinuano, B = Brahman, and A = Angus):

Reciprocal F₁ were considered separate breed groups. The resultant number of births was greater than 100 for each of these breed groups (Table 1).

Calving difficulty for each birth was assessed by assignment of a subjective score from 1 to 4: 1 represented no assistance; 2 indicated a minor hand pull; 3 indicated a moderate to major hand pull; and 4 indicated major mechanical assistance. A subjective score was also assigned as an assessment of calf vigor at birth: 1 indicated normal, adequate vigor; 2 indicated a weak calf that nursed without assistance; and 3 represented a calf too weak to nurse without assistance. Stillbirths (calves dead when found and thought to be dead at birth) were assigned a vigor score of 0.

Calves were vaccinated (5-way vibrio/lepto; 7-way clostridial + H. somnus; 4-way respiratory + Pasturella) at an average age of 4 to 5 mo and were revaccinated 3 wk before weaning. Calf age at weaning ranged from 154 to 274 d with an average of 229 d. Calf body weight, hip height, and BCS were collected at weaning. Body condition scores (1 to 9) were an adaptation of those described for mature cows by Herd and Sprott (1986). Each year, weaning occurred on unique dates on 3 consecutive weeks in September, for 1 management unit per week.

Statistical Analyses
Data were analyzed using the MIXED procedure (SAS Inst. Inc., Cary, NC). The appropriate models for birth weight, preweaning ADG, weaning weight, BCS, and hip height were built from the basic model:

where Y_ijklmn = the nth observation; µ = the overall mean; SB_i = the fixed effect of the ith sire breed group, i = R, B, or A; DB_j = the fixed effect of the jth dam breed group, j = R, B, or A; M_k = the fixed effect of the kth project year; (SB x DB)_ij = the fixed effect of the ijth sire breed-dam breed combination; S(SB)_il = the random effect of the lth sire within the ith sire breed; D(DB)_jm = the random effect of the mth dam within the jth dam breed; and e_ijklmn = the random error associated with the nth observation.

Other fixed effects, both main effects and interactions, were investigated in preliminary analyses. Management unit effects were modeled with 3 levels. A 2-level cow winter nutritional program was employed for a single winter before calving in the first project year; it was investigated as a fixed effect. Calf sex was modeled in 2 levels. Cow age categories (n = 8) were constructed corresponding to years of age and consisted of 3, 4, 5, 6 (all cows from the sixth through the ninth yr of age were included in this category), 10, 11, 12, and 13 (older cows were included in this category). Linear and quadratic regressions on calf age in days were investigated for weaning traits. Any investigated model component with a small F-ratio (P > 0.25) was excluded from the final analyses.

Breed group (SB x DB) was the effect of interest. Records from twins (6 sets) were excluded from analyses of birth and weaning traits. If either twin survived to 4 d of age or to weaning, the record for only that twin was included in the analyses of mortality before those times. Five cows became lame at various times late in lactation in different years; their calves’ weaning records were excluded from the analyses. One cow and calf were killed by lightning; this calf’s record was excluded from the preweaning mortality analysis.

Source of Angus.
Analyses were performed to assess the potential effect of source of Angus sire on the traits studied. All models used sire and dam breed categories as described above. The effect of source of Angus sire was then evaluated for these traits by dividing the Angus sire breed into 2 categories: those born and raised in the station herd (n = 6 bulls) and those from outside sources (n = 8 bulls). This resulted in a 4-level sire breed effect (1 Romosinuano, 1 Brahman, and 2 Angus groups) rather than the 3-level effect previously described. Linear functions of the appropriate sire breed means (outside source minus within herd) and interactions were used to assess Angus sire source differences for each trait. When this estimate was significantly different from 0, linear functions were used to compare Angus sire sources within each dam breed level. To estimate parameters without external influence when the source of sire was significant, a final analysis was conducted in which data from calves sired by Angus bulls from outside sources were excluded.

Analyses of Binomial Traits.
Calving difficulty, calf vigor, and calf survival to weaning were analyzed as binomial traits using the FREQ procedure of SAS. For calving difficulty, scores of 1 (normal births) were assigned a value of 0, and all other scores (which indicated some difficulty was present) were assigned a value of 1. Means, therefore, represented proportions of difficult births. Similarly, calves with adequate vigor at birth (score 1) were assigned a value of 0. Calves with inadequate vigor (all subjective vigor scores except 1) were assigned values of 1. The proportion of deaths before 4 d of age and before weaning were calculated by assigning values of 1 to all deaths in both periods and values of 0 to calves that survived to 4 d of age and to weaning. For each of these traits, source of Angus sire was tested against the ² expectation, across and within all dam breeds. Subsequently, sire breed (with 3 or 4 levels, based upon the Angus source test) x dam breed combinations were tested against the ² expectation.

Genetic Effects
Breed effects and heterosis were estimated using contrasts of least squares means for sire breed x dam breed combinations (and interactions when significant). These were constructed based on the methods of Dickerson (1973). In the contrasts detailed below, n = 3 represents the number of breeds; P_i = the mean for the ith pure breed; _n = the mean for the pure breeds excluding the ith pure breed; X_ij = the mean for the cross of breed i sires with breed j dams; and pairs of letters indicate sire breed x dam breed interaction means.

Direct breed effects (g^I) were calculated as

[1]

Maternal breed effects (g^M) were calculated as

[2]

Specific direct heterosis (h) was calculated as

[3]

In equations 1, 2, and 3,

Finally, single-degree contrasts (n = 3) were used to assess the differences between the heterosis estimates of the 3 pairs of breeds for each trait.

	RESULTS AND DISCUSSION

Top Abstract INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION IMPLICATIONS LITERATURE CITED

 
The numbers of records for each trait, along with means and SD are shown in Table 2. The sire breed x dam breed interaction was highly significant in analyses of birth weight and weaning traits (Table 3). Males had greater preweaning ADG and weaning hip height than females (Table 4); however, female BCS at weaning was greater than males (P = 0.05). In most cases, cows in age category 6 (ages 6 through 9 yr) had calves with greater birth weight, weaning weight, preweaning ADG, and weaning hip height than cows in other age categories. Young and old cows generally had calves with lower birth and weaning weight, preweaning ADG, and hip height. Cow age was not retained in final analyses of BCS (P = 0.42). The 3-way interaction of sire breed, dam breed, and sex was included for birth weight (P < 0.001) and weaning weight (P = 0.05). Calf age at weaning was highly significant as a linear covariate in analyses of BCS (0.002 ± 0.0004), weaning weight (0.82 ± 0.03 kg), and weaning hip height (0.1 ± 0.01 cm).

Birth weights of male calves were greater (P < 0.05) in all breed groups except crossbred calves from Brahman dams, in which female birth weights exceeded (P < 0.05) male birth weights (Table 5). Within sex, Romosinuano calves were lighter (P < 0.05) at birth than calves from all Brahman-sired groups. Romosinuano male birth weight was greater (P < 0.05) than Angus male birth weight. Consistent with previous reports (Cartwright et al., 1964; Roberson et al., 1986; Thallman et al., 1992): 1) Brahman-sired F₁ calves had heavier birth weights than reciprocal cross calves, 2) those reciprocal differences were greater in males than females, and 3) Brahman-sired crossbred bull calves were much heavier (4.6 kg for Brahman-Romosinuano and 5.7 kg for Brahman-Angus, P < 0.05) than Brahman-sired female calves. Romosinuano-Angus birth weight means were lower (P < 0.05) than Brahman-sired F₁ birth weights. It appears that any advantages of Romosinuano adaptation could be incorporated into a breeding program without concern about the birth weight issues associated with breeding Brahman to Bos taurus females.

With the exception of Brahman, purebred means for weaning weight were very low relative to crossbred means. Romosinuano weaning weight means for both sexes were lower (P < 0.05) than all other breed groups (within sex) except Angus and Romosinuano-sired calves from Angus dams (Table 5). Although they were lighter (P < 0.05) than Angus-sired calves from Brahman dams, Romosinuano-Brahman reciprocal cross-bred calves of both sexes had among the heaviest weaning weight means. Steer calves were significantly heavier than heifer calves in all sire breed x dam breed groups. Sex differences in weaning weights of Brahman-sired calves were largest (17.8, 17.3, and 17.8 kg from Brahman, Romosinuano, and Angus dams, respectively), along with Angus-sired calves from Romosinuano dams (17.8 kg). The sex differences for purebred Romosinuano and Romosinuano-sired calves from Angus dams were almost as large (15.3 and 12.9 kg, respectively). Within the respective crossbred groups, the differences between reciprocal breed group weaning weights were large (21.7 kg or greater), except for Brahman-Romosinuano crosses.

Romosinuano purebreds had lower (P < 0.05) pre-weaning ADG and BCS relative to most other breed groups (Table 6). Purebred Angus and Romosinuano-sired calves from Angus dams were most similar to the purebred Romosinuano for these traits. All other crossbred Romosinuano groups were similar to Brahman-Angus F₁ for preweaning ADG. Romosinuano-Angus F₁ calves had lower (P < 0.05) BCS than either Brahman-Angus group. Romosinuano calves had greater (P < 0.05) weaning hip height than Angus calves and Romosinuano-sired calves from Angus dams but were significantly lower than weaning hip height of all breed groups with any Brahman. The differences between reciprocal crossbred groups were large (55.1 g/d or greater) for preweaning ADG and for hip height of Romosinuano-Angus and Brahman-Angus breed groups (4.5 cm or greater). In each dam breed group, calves sired by Angus bulls from outside sources had greater (P < 0.05) hip height than calves sired by Angus bulls from the STARS herd (0.9 to 2.2 cm).

Estimates of heterosis for weaning weight, preweaning ADG, and hip height in Romosinuano crosses were within the range of reported estimates from others, although they were, in general, lower than the estimates from Bos indicus-Bos taurus crosses. Estimates of heterosis for weaning weight (or related traits, e.g., 200-d weight, etc.) from literature ranged from less than 10% for British crosses (Gregory et al., 1965; Comerford et al., 1987) and Bos indicus-Bos taurus crosses (Prayaga, 2003) to much greater estimates of 16 to 21% for Brahman crosses and for some Continental crosses (Cartwright et al., 1964; Peacock et al., 1978; Comerford et al., 1987). Estimates of weaning weight heterosis for Brahman paired with other breeds ranged from 10 to 24 kg, and all other pairs of breeds ranged from –8 to 90 kg in the work of Wyatt and Franke (1986). Prayaga (2003) reported 8.0% heterosis in Zebu-Adaptaur crosses for preweaning ADG; Wyatt and Franke (1986) reported estimates for Brahman with all other breeds from 47 to 100 g/d and a range for all other pairs of breeds from 5 to 155 g/d. Heterosis for preweaning ADG (41 g/d, 6.2%) in Nelore-Angus and Nelore-Hereford F₁ calves (Teixeira and Albuquerque, 2005) was slightly lower than that of the current study, and significant heterosis estimates for Senepol-Hereford crosses (when crossed with Hereford; Chase et al., 1998) for 200-d weight and ADG were slightly less (5.1 and 5.4%, respectively) than those for Romosinuano-Angus in the current study. Estimates of heterosis for hip height at weaning were approximately of the same magnitude as those of Comerford et al. (1988) for yearling hip height of Brahman with Simmental, Limousin, and Hereford (1.4 to 2.9%).

Direct and Maternal Breed Effects
The Romosinuano direct breed effect was to lower birth weight, weaning weight, preweaning ADG, and BCS; estimates were the lowest of the 3 breeds (Table 7). Angus direct effects were the largest for ADG, but Brahman direct effects were the largest positive estimates for all other traits. Brahman direct effects on birth weight as deviations from Romosinuano or Angus (greater than 9.1 kg) were more than 2 times larger than Brahman deviations from Adaptaur or Hereford (Roberson et al., 1986; Prayaga, 2003) but only slightly greater than the estimate in subtropical Australia (7.8 kg) as a deviation from Hereford (Arthur et al., 1999). Estimates of Brahman direct effects on weaning weight and preweaning ADG were negative in temperate environments (Arthur et al., 1999) and also in Central Texas but of lower magnitude (Roberson et al., 1986). Estimates of Brahman direct effects on birth weight were similar to that (7.4 kg) reported by Wyatt and Franke (1986). Those authors also reported a negative (–22 g) Brahman direct effect for preweaning ADG but failed to detect a significant Brahman direct effect on weaning weight. Chase et al. (1998) failed to detect significant Senepol direct effects for birth or weaning weight or preweaning ADG.

Estimates of Romosinuano maternal effects were positive and the greatest of the 3 breeds for birth weight and weaning hip height (Table 7) but were less than Brahman maternal effect estimates for weaning weight and preweaning ADG. Romosinuano maternal breed effects were of lower magnitude than those Senepol maternal effects on weaning weight and ADG (as a deviation from Hereford; Chase et al., 1998). The estimate of Brahman maternal effects on birth weight was large and negative, consistent with other reports (Wyatt and Franke, 1986; Arthur et al., 1999; Prayaga, 2003), but for all other traits, the Brahman maternal effect estimates were large and positive. Brahman maternal effects on weaning weight as deviations from Angus (40.2 kg) were much larger than those reported as deviations from British breeds (range of –8.2 to 13.3 kg; Roberson et al., 1986; Arthur et al., 1999; Prayaga, 2003). Of the 3 breeds in the current study, estimates for Angus maternal effects were the most negative for weaning weight, preweaning ADG, and weaning hip height.

Although there were significant differences between Angus sire source hip height means, the exclusion of hip height records from calves sired by outside source Angus sires had only minor influences on the estimated genetic parameters. These analyses (records from calves of outside Angus-sires excluded) produced significant estimates of heterosis for Romosinuano-Angus (2.2 ± 0.4 cm; 1.9%) and Brahman-Angus (4.2 ± 0.5 cm; 3.4%) that were slightly larger than those produced from analyses of all data (Table 7). The estimates of direct effects on weaning hip height were not different from 0 (P = 0.90) for Romosinuano; those for Brahman (7.1 ± 1.2 cm) and Angus (–7.0 ± 1.4 cm) were of slightly greater magnitude than those in Table 7. Estimates of maternal effects were significant but of slightly lower magnitude than those in Table 7 for all breeds: 2.5 ± 0.6, 2.1 ± 0.7, and –4.6 ± 0.8 cm for Romosinuano, Brahman, and Angus, respectively.

Binomial Traits
Calving difficulty was the leading known cause of death and implicated in 19 of the 85 deaths. The breed group means for proportion of difficult births differed from ² expectation (Table 8; P < 0.02). No calving difficulty was observed in any Romosinuano-sired breed group or among Angus-sired calves from Brahman dams. Romosinuano-sired F₁ calves from MARC III and Angus dams in Nebraska had the highest (significantly higher than Angus, Hereford, and Beefmaster F₁ calves) percentage of unassisted calvings (99.2%) and the most favorable calving difficulty score (significantly better than Angus and Hereford F₁ calves) among the breeds evaluated in the Germplasm Evaluation (GPE) Cycle VIII (Wheeler et al., 2006). The high proportion of difficult births observed in calves sired by Brahman bulls and from Angus dams was totally consistent with the large birth weight (Table 6) observed for this breed group. This result was consistent with high mortality of Brahman-sired calves from Adaptaur cows due to dystocia reported by Prayaga (2004). Romosinuano females appeared to have a calving ease advantage that was independent of birth weight suppression. Even though Brahman-sired calves from Romosinuano dams had very large birth weights (Table 6), only 1 calf in this group was born in a difficult birth. The high (relatively) proportion of difficult births in the purebred Brahman group was not expected because Brahman maternal suppression of birth weight and lower incidence calving difficulty is well known. This greater proportion did not appear to be a result of increased birth weight because purebred Brahman means were similar to the others (Table 6). No estimates of heterosis for calving difficulty (or other binomial traits) were possible, because as "...a trait approaches an incidence of 100%, there is little opportunity for the expression of hybrid vigor in crossbreds" (Crockett et al., 1978). Crossbred calving difficulty means (average of reciprocal crosses) were the same or better (less than) than purebred averages with the exception of the high Brahman-Angus group. Estimates of heterosis for calving difficulty that were summarized by Long (1980) ranged from 1.3 to 56%; however, Comerford et al. (1987) failed to detect significant heterosis for calving ease for any pair of breeds in that study (Brahman, Simmental, Limousin, and Hereford).

The majority (57 of 85 deaths; 67%) of calf mortality occurred before 4 d of age (Table 8). Calving difficulty in Brahman-sired calves from Angus dams resulted in this breed group having the greatest mortality before 4 d of age and the third greatest preweaning mortality. Purebred Brahman and Angus had large proportions of calf mortality for both time periods; the majority of these were not due to calving difficulty. Almost half of all preweaning deaths (39) were from purebred groups. Half or more of the calf mortality observed in breed groups with Romosinuano dams occurred after 4 d of age. In all other breed groups, 0 to 40% of deaths occurred after 4 d of age. Average crossbred mortality was numerically lower than purebred mortality before 4 d and preweaning. Romosinuano F₁ calves had the highest percentage survival to weaning (98.6%; not significantly higher than any other group) of all breeds in GPE Cycle VIII (Wheeler et al., 2006). Insignificant estimates of heterosis were reported for calf survival in tropical Australia (Prayaga, 2004), and Long (1980) reported a range of heterosis estimates from –1 to 3% for survival at birth and from –2 to 15% for survival to weaning.

Source of Angus sire x dam breed means differed from expectation for mortality proportions (but not calving difficulty or calf vigor proportions). Mortality before 4 d of age for calves sired by Angus bulls from the research herd was less than 0.04 across all dam breeds (source proportions differed from expectation, P < 0.001). Outside-source Angus-sired calves from Angus dams had the greatest numbers of deaths and the greatest mortality in the 2 time periods, but almost all of the deaths occurred before 4 d of age (n = 8 before 4 d of age, 0.12 ± 0.04; n = 9 before weaning, 0.14 ± 0.04). All other Angus source x dam breed groups had 2 or less deaths (range of proportions from 0.02 ± 0.01 to 0.03 ± 0.02) before 4 d of age and 4 or less preweaning deaths (range from 0.03 ± 0.02 to 0.07 ± 0.04).

	IMPLICATIONS

Top Abstract INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION IMPLICATIONS LITERATURE CITED

 
These first estimates of heterosis and breed effects for a Criollo breed crossed with the predominant Bos taurus and Bos indicus breeds used in the United States permit prediction of performance in crossbreeding programs. Results from these evaluations of preweaning calf traits favor use of Romosinuano in crossbreeding systems, particularly with Brahman, rather than as purebreds. Romosinuano sires may provide sufficient adaptation to Florida environments without the large birth weights and calving difficulty associated with the use of Brahman sires. The relatively low proportion (compared with Angus dams) of calving difficulty in spite of high calf birth weights of Romosinuano cows bred to Brahman bulls should be further investigated. Other Criollo breeds may offer similar adaptation but with different production strengths; they should be investigated in similar scenarios.

	Footnotes

 
¹ Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product to the exclusion of others that may also be suitable.

² Appreciation is extended to E. L. Adams, E. J. Bowers, M. L. Rooks, V. E. Rooks, and all of the STARS staff for technical assistance and animal care.

³ Corresponding author: dgriley{at}ifas.ufl.edu

Received for publication June 29, 2006. Accepted for publication September 8, 2006.

	LITERATURE CITED

Top Abstract INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION IMPLICATIONS LITERATURE CITED

 


Arthur, P. F., H. Hearnshaw, and P. D. Stevenson. 1999. Direct and maternal additive and heterosis effects from crossing Bos indicus and Bos taurus cattle: Cow and calf performance in two environments. Livest. Prod. Sci. 57:231–241.[CrossRef]

Cartwright, T. C. 1980. Prognosis of Zebu cattle: Research and application. J. Anim. Sci. 50:1221–1226.[Abstract/Free Full Text]

Cartwright, T. C., G. F. Ellis, Jr., W. E. Kruse, and E. K. Crouch. 1964. Hybrid vigor in Brahman-Hereford crosses. Tech. Monogr. 1. Texas Agricultural Experiment Stn. College Station.

Chase, C. C., Jr. 2002. Embryo transfer in tropically adapted cattle in the semitropics. Page 145 in Factors Affecting Calf Crop, Biotechnology of Reproduction, M. Fields, R. S. Sand, and J. V. Yelich, ed. CRC Press, Boca Raton, FL.

Chase, C. C., Jr., T. A. Olson, A. C. Hammond, M. A. Menchaca, R. L. West, D. D. Johnson, and W. T. Butts, Jr. 1998. Preweaning growth traits for Senepol, Hereford, and reciprocal crossbred calves and feedlot performance and carcass characteristics of steers. J. Anim. Sci. 76:2967–2975.[Abstract/Free Full Text]

Comerford, J. W., J. K. Bertrand, L. L. Benyshek, and M. H. Johnson. 1987. 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. J. Anim. Sci. 64:65–76.[Abstract/Free Full Text]

Comerford, J. W., J. K. Bertrand, L. L. Benyshek, and M. H. Johnson. 1988. Evaluation of performance characteristics in a diallel among Simmental, Limousin, Polled Hereford and Brahman beef cattle. I. Growth, hip height, and pelvic size. J. Anim. Sci. 66:293–305.[Abstract/Free Full Text]

Crockett, J. R., M. Koger, and D. E. Franke. 1978. Rotational crossing of beef cattle: Reproduction by generation. J. Anim. Sci. 46:1163–1169.[Abstract/Free Full Text]

de Alba, J. 1984. El Bovino Romosinuano en Turrialba. CATIE, Turrialba, Costa Rica.

Derr, J. N., S. K. Davis, J. L. Estrada, J. E. Ossa, M. Westhusin, J. Piedrahita, and L. G. Adams. 1995. Genetic characterization and conservation of Colombian Criollo cattle. Pages 304–313 in Conservation of Domestic Animal Genetic Resources. R. D. Crawford, E. E. Lister, and J. T. Buckley, ed. Rare Breeds International, Warwickshire, UK.

Dickerson, G. E. 1973. Inbreeding and heterosis in animals. Pages 54–77 in Proc. Animal Breeding and Genetics Symp. in Honor of Dr. Jay L. Lush. Am. Soc. Anim. Sci., Champaign, IL.

Elzo, M. A., C. Manrique, G. Ossa, and O. Acosta. 1998. Additive and nonadditive genetic variability for growth traits in the Turipaná Romosinuano-Zebu multibreed herd. J. Anim. Sci. 76:1539–1549.[Abstract/Free Full Text]

FAO. 1993. Page 264 in World Watch List for Domestic Animal Diversity. Food Agricultural Organization. R. Loftus and B. Scherf, ed. United Nations, Rome, Italy.

Franke, D. E. 1980. Breed and heterosis effects of American Zebu cattle. J. Anim. Sci. 50:1206–1214.[Abstract/Free Full Text]

Franke, D. E., O. Habet, L. C. Tawah, A. R. Williams, and S. M. DeRouen. 2001. Direct and maternal genetic effects on birth and weaning traits in multibreed cattle data and predicted performance of breed crosses. J. Anim. Sci. 79:1713–1722.[Abstract/Free Full Text]

Frisch, J. E., and C. J. O’Neill. 1998. Comparative evaluation of beef cattle breeds of African, European and Indian origins. 1. Live weights and heterosis at birth, weaning and 18 months. Anim. Sci. 67:27–38.

Gregory, K. E., L. A. Swiger, R. M. Koch, L. J. Sumption, W. W. Rowden, and J. E. Ingalls. 1965. Heterosis in preweaning traits of beef cattle. J. Anim. Sci. 24:21–28.[Abstract/Free Full Text]

Herd, D. B., and L. R. Sprott. 1986. Body condition, nutrition, and reproduction of beef cows. Rep. B-1526. Texas Agricultural Experiment Stn., College Station.

Long, C. R. 1980. Crossbreeding for beef production: Experimental results. J. Anim. Sci. 51:1197–1223.[Abstract/Free Full Text]

Martinez-Correal, G. 1995. The Colombian Criollo breeds. Pages 161–166 in Conservation of Domestic Animal Genetic Resources. R. D. Crawford, E. E. Lister, and J. T. Buckley, ed. Rare Breeds International, Warwickshire, UK.

Payne, W. J. A. 1970. Breeds and Breeding. Pages 28–61 in Cattle Production in the Tropics, Volume 1. Longman Group Ltd., London, UK.

Peacock, F. M., M. Koger, and E. M. Hodges. 1978. Weaning traits of Angus, Brahman, Charolais and F₁ crosses of these breeds. J. Anim. Sci. 47:366–369.[Abstract/Free Full Text]

Plasse, D., H. Fossi, R. Hoogesteijn, O. Verde, R. Rodríguez, C. Rodríguez M., and P. Bastidas. 1995. Growth of F₁ Bos taurus x Bos indicus versus Bos indicus beef cattle in Venezuela. I. Weights at birth, weaning and 18 months. J. Anim. Breed. Genet. 112:117–132.

Prayaga, K. C. 2003. Evaluation of beef cattle genotypes and estimation of direct and maternal effects in a tropical environment. 1. Growth traits. Aust. J. Agric. Res. 54:1013–1025.[CrossRef]

Prayaga, K. C. 2004. Evaluation of beef cattle genotypes and estimation of direct and maternal effects in a tropical environment. 3. Fertility and calf survival traits. Aust. J. Agric. Res. 55:811–824.[CrossRef]

Riley, D. G., C. C. Chase, Jr., T. A. Olson, S. W. Coleman, and A. C. Hammond. 2004. Genetic and nongenetic influences on vigor at birth and preweaning mortality of purebred and high percentage Brahman calves. J. Anim. Sci. 82:1581–1588.[Abstract/Free Full Text]

Roberson, R. L., J. O. Sanders, and T. C. Cartwright. 1986. Direct and maternal genetic effects on preweaning characters of Brahman, Hereford and Brahman-Hereford crossbred cattle. J. Anim. Sci. 63:438–446.[Abstract/Free Full Text]

Rouse, J. E. 1977. Pages 133–165 in The Criollo: Spanish Cattle in the Americas. Univ. Oklahoma Press, Norman.

Teixeira, R. A., and L. G. Albuquerque. 2005. Heteroses maternal e individual para ganho de peso pré-desmama em bovinos Nelore x Hereford e Nelore x Angus. Arq. Bras. Med. Vet. Zootec. 57:518–523.

Thallman, R. M., J. O. Sanders, and J. F. Taylor. 1992. Non-Mendelian genetic effects in reciprocal cross Brahman x Simmental F₁ calves produced by embryo transfer. Beef Cattle Research in Texas, 1992 PR-5053:8–14. Texas Agricultural Experiment Stn., College Station.

Thrift, F. A., and T. A. Thrift. 2005. Rationale for evaluating alternative sources of subtropically adapted beef cattle germplasm. Pages 6–15 in A Compilation of Research Results Involving Tropically Adapted Beef Breeds. Bull. 405. Southern Cooperative Series. Louis. Agric. Exp. Stn., Baton Rouge.

Turner, J. W. 1980. Genetic and biological aspects of Zebu adaptability. J. Anim. Sci. 50:1201–1205.[Abstract/Free Full Text]

Wheeler, T. L., L. V. Cundiff, L. D. Van Vleck, G. D. Snowder, R. M. Thallman, S. D. Shackelford, and M. Koohmaraie. 2006. Preliminary results from cycle III of the cattle germplasm evaluation program at the Roman L. Hruska U.S. Meat Animal Research Center. Germplasm Evaluation Program Progress Rep. No. 23. ARS, USDA, Clay Center, NE.

Wyatt, W. E., and D. E. Franke. 1986. Estimation of direct and maternal additive and heterotic effects for preweaning growth traits in cattle breeds represented in the Southern region. Bull. 310. Southern Cooperative Series. Louisiana Agricultural Experiment Stn., Baton Rouge.

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Riley, D. G. Articles by Olson, T. A. Search for Related Content PubMed PubMed Citation Articles by Riley, D. G. Articles by Olson, T. A.