Crossbreeding

Evaluation of the productivity of the Brahman, with other breeds and their crosses in East and Southern Africa

Abstract
Studies from Southern Africa, were reviewed, where Brahmans were compared with other breeds. Genotype x environment interactions were apparent and of important magnitude. In general, the Brahman sire and dam performed well and under difficult conditions (eg. Swaziland) the crossbred Brahman excelled. Fitness traits below.

Growth of progeny with Brahman breeding compared well with other breeds, especially 18 month weight. Feedlot performance was poor, primarily due to a lack of appetite. Carcass quality (eye muscle area and intra-muscular fat) of two year old progeny was also poor, indicating a slow maturing animal.

Introduction
Optimal productivity of a beef enterprise can be significantly influenced by the selection of the appropriate breed, or breed combinations, and environment. The numerous breeds of cattle in East and Southern Africa can be classified into three basic types: indigenous; Bos Taurus; and Bos Indicus. Indigenous cattle, also termed Sanga cattle (Mason and Maule, 1960), are characterised by a Bos Taurus and Bos Indicus.

These breeds are thought to have originated from crosses between humpless and zebu (Bos. Indicus) cattle in the horn of Africa between 5 000 and 1 500 B.C. As people migrated southwards along the east coast of Africa they brought these cattle with them. The B. Taurus (British and European) and B. Indicus (namely the Brahman) cattle are recent introductions to Africa. The Brahman was developed in the southern United States from Indian B. Indicus breeds.

Until 15 years ago, information on the relative performance of beef breeds and their crosses in East and Southern Africa was scant. Agricultural research and commercial production emphasized reproductive performance and growth rate in exotic cattle. In general, maternal traits and production from cattle indigenous to Africa were ignored. Hetzel summarized the results of comparative studies carried out in a number of countries in East and Southern Africa. Some of the findings of this review were:

●  Breed x environment interactions are apparent.
●  Indigenous cattle are generally productive due to their ability to reproduce to a hard environment.
●  Maternal performance is not enhanced by crossing indigenous cattle with Bos Taurus or Bos. Indicus.
●  Crossbreeding to improve progeny growth rate using superior indigenous breeds as dams and exotic B. Taurus or controlled breeding is feasible.
●  Sanga and B. Indicus (eg Brahman and Boran) crosses should be evaluated in stressful environments.
●  A need to study adaptive traits.

Since Hetzel’s review, a comprehensive analysis of a large crossbreeding study in Zimbabwe has been completed which includes post-weaning growth and carcass information. Findings from both the National Beef Cattle Breeding Programme in Swaziland and the Beef Cattle Performance and Progeny Testing Scheme of South Africa have also been reported. These three reports all included an evaluation of the Brahman and will be used to update Hetzel’s review, with attention focused on the Brahman.

●  Table 1:  Comparative maternal productivity of beef breeds evaluated in Zimbabwe
●  Table 2:  Comparative maternal productivity of beef breeds in South Africa
●  Table 3:  Comparative maternal productivity of beef breeds evaluated in Swaziland
●  Table 4:  Comparative maternal productivity of beef breeds evaluated in Botswana
●  Table 5:  Effects of sire breed on progency growth (kg) to 18 months of age
●  Table 6:  Effects of breed of sire on carcass traits of feedlot progency
●  Table 7:  Effects of breeds of dam on carcass traits of feedlot progency

The mature weight of the cow is an important aspect to consider for sustainable production and generally, smaller cows are suited to harsher environments. The use of a smaller breed, however, can compromise growth rates. The mature weight of the Brahman female was found to be intermediate when compared with the smaller Sanga (Mashona, Nguni and Nkone) and the larger European B. Taurus type cow (Charolais and Simmental) (Table1, Table 2 and Table 3).

It is generally accepted that the Brahman is a sexually late maturing breed and has low levels of fertility. However, data from South Africa (Table 2) and Swaziland (Table 3) show that the Brahman is intermediate with respect to age at first calving. The Angus, Sussex, Bonsmara, Pinzgauer and Simmental breeds on average calved when they were three months younger and Drakensberger and Afrikaner breeds when they were three to four months older than the Brahman (Table 2).

Conflicting results were found with respect to fertility (expressed as either calving interval or calving rate). The Brahman was found to be intermediate in Zimbabwe and South Africa (Tables 1 and 2) but relatively poor in Swaziland and Botswana (Tables 3 and 4). Hetzel also noted that the calving rate of the Brahman was high in the Zimbabwean study (Table 1) and attributed this to the hardiness of the breed in “low” performance environments.

However, his classification of “Low” and High” performance environments was partly based on the calving rate of the Afrikaner. The cows in the Zimbabwean study were not culled for infertility, but after simulated culling for two consecutive failures the calving rate of the Afrikaner dam was increased from 56 to 62 percent. This compared with 67 percent in the Botswanan study (Table 4). In the Zimbabwean study, large differences were found between reciprocal crosses with the Afrikaner. The fertility of a cow sired by an Afrikaner was markedly depressed when compared with the fertility of a cow from an Afrikaner dam.

The survival rate of purebred and crossbred calves from purebred Brahman cows tended to be the lowest of the breeds evaluated (Tables 1,2 and 4) and concurs with findings  the United States and South America. This was most noticeable in the Botswanan study, where the survival rate of calves born to Bonsmara and Brahman cows was 14 to 16 percent lower than those of calves born to Sanga cows (Tswana, Tuli and Afrikaner; Table 4). In contrast, the survival rates of calves born to Brahman cross cows were among the highest (Tables 1, 2 and 4).
Lowest calf birth weights were recorded in the small Sanga breeds (Mashona and Nguni; Tables 1, 2 and 3). The birth weights of calves born to Brahman cows were also very low and ranged from 10 to 30 percent (three to 10kg) lighter than calves born to other breeds, especially those of the larger European breeds (Tables 1, 2, 3 and 4). The ability of the Brahman cow to restrict the size of her calf has been well documented.

Weaning weight of calf, as a trait of the dam, showed extreme variation across studies (Tables 1. 2, 3 and 4), indicative of the presence of breed x environment interactions. The weight of calf weaned from the Brahman cow was among the lowest of the cow genotypes in the Botswana study (Table 4), intermediate in South Africa (Table 2) and among the best, together with Brahman crosses, in Zimbabwe and Swaziland (Tables 1 and 3).

In the Zimbabwean study, Brahman and Afrikaner x Brahman dams gained the least weight between parturition and weaning (7 kg as compared with 20 kg for all other genotypes). This indicates that the Brahman cow devotes more energy to milk production, rather than replenishing her body reserves, which may account for the improved weaning performance. Turner reported similar findings, nothing that the Brahman cow may devote excess energy to her calf to the detriment of subsequent fertility.

Information on weight of calf at 18 months as a trait of the dam was only available for the Zimbabwean and Botswanan studies (Tables 1 and 4). The superior pre-weaning growth rate of crossbred calves from purebred Brahman cows in the Zimbabwean study continued post-weaning, where calves were between 8 and 13 percent heavier than calves from other purebred dams evaluated. None of the progeny from crossbred dams were heavier than the progeny from the purebred Brahman dams (Table I).

It is noteworthy that of the five crosses that showing similar performance to the Brahman, four were Brahman crosses. Similar results were shown in Botswana, although calves from Bonsmara dams were heavier at 18 months than calves from Brahman dams (Table 4). Among the crossbred dam genotypes, weight of 18 month old calves from Simmental and Brahman crossbred dams were five to seven percent superior to calves from Tuli and Bonsmara crossbred and purebred Tswana dams (Table 4).

Realistic measures of cow productivity take into account fertility, calf survival and growth, and cow weight. Expressing rates. Weight of calf per unit weight of cow attempts to include maintenance costs as well, thus enabling the comparison of cows of differing mature weight. However, this assumes that breeds are equally adapted, ie. environment constraints do not affect breeds differently. These are biological indices; economical values depend on other factors as indicated by Hetzel.

When productivity was expressed as weight of calf weaned per cow exposed, the Brahman was the poorest in the Botswana study (Table 4), intermediate in South Africa and Swaziland (Tables 2 and 3), but was one of the best cow genotypes in the Zimbabwean study (Table 1).

Brahman crossbred cow genotypes evaluated were intermediate in Botswana (Table 4), among the best in Zimbabwe (Table 1) and outstanding in Swaziland (Table 3).

When weaning production was expressed per unit metabolic weight (weight .75), despite the relatively low growth rate of their progeny, the small Sanga cattle were among the most productive genotypes because of their relatively high fertility and calf survivability and low mature weight (Tables 1, 2 and 3). Even when weight of cow was taken into account, the Brahman female performed well, being intermediate in Swaziland (Table 3) and among the best genotypes in Zimbabwe (Table 1) and South Africa (Table 2). Similar trends to the above were shown for 18 month weight cow calf expressed either per cow or per unit weight of cow.

Sire Effects
Literature, describing sire influences on comparative growth of the Brahman and other breeds in east and southern Africa, is available from a limited number of studies only: Zimbabwe (Moyo, 1990); Botswana (Trail et al., 1977; Apru, 1979); South Africa (Mentz et al., 1979a,b; Scholtz, 1988).

The birth, weaning and 18 month weight data from the Zimbabwean and Botswanan (Apru, 1979) studies have been summarized in Table 5. In the Botswanan study the first set of data compared five sire breeds across stations and the second set compared seven at one station. Birth weight of calves sired by Brahman were among the heaviest, together with calves sired by Italian (Chianina, Marchigiana and Romagnola), Simmental and South Devon bulls (Table 5). In the Zimbabwean study calves sired by Brahmans were intermediate within a narrow weight range (Table 5). However, sire*s effects may have been masked because they were mated to a range of purebred and crossbred cows.

Weaning weight of calves sired by Brahman bulls were intermediate (Table 5; Mentz et al., 1979a) to the other sires evaluated. Calves were three to nine percent lighter than those sired by Simmental and Charolais and were six to12 percent heavier than those sires by Aberdeen Angus, Tuli, Tswana and Afrikaner. However, 18 month weight of progeny sired by Brahman were among the heaviest and were only two percent lighter than those sired by Simmental, Holstein-friesian and Italian breeds and eight percent heavier than those sired by the Sanga breeds (Tuli, Tswana and Afrikaner; Table 5).

Carcase Traits
Moyo presented sire and dam genotype influences on carcass traits (Tables 6 and 7). At 19 months of age, all animals were taken off the range and put into a feedlot. They were allocated within sex and sire group to three different amounts of their appetites, determined their length of stay in the feedlot.

While progeny from Brahman sire and dam genotypes were among the heaviest at induction into the feedlot (18 month weight; Tables 1 and 5), their appetite in the feedlot was small and similar to that of Afrikaner and Tuli sired progeny (Ward and Dlodlo, 1986). Thus the pre-slaughter and carcass weights of progeny from the Sanga (Afrikaner, Mashona, Nkone and Tuli), Brahman and crosses among them were the lowest. Similar trends were reported in South Africa where the average daily gain of the Afrikaner, Brahman and Nguni in the feedlot were the lowest. Progeny with B. Taurus breeding had the highest pre-slaughter and carcass weight, since small differences were found in carcass length.

Progeny with Brahman breeding had the smallest eye muscle area together with Afrikaner, Hereford and Holstein-Friesian sired progeny. Largest eye muscle area were from progeny with Charolais and Simmental breeding. Carcasses with Brahman breeding were intermediate for sub-cutaneous fat cover, but contained least intra-muscular fat. Aberdeen Angus sired progeny had the highest quantities of sub-cutaneous fat, while progeny with Charolais and Simmental breeding had the least sub-cutaneous fat.

Summary
Interpretation of data requires care, especially when attempting to extrapolate to different environments in the presence of genotype x environment interactions. The studies evaluated here show that the Brahman sire and dam performed well and have a role to play in Southern Africa. The productivity of the Brahman dam did not exceed that of the indigenous Sanga breeds.

However, crosses with the Brahman offered great potential particularly under extensive conditions, for example in Swaziland, where Brahman x Nguni first cross females showed more than 50 percent improvement in productivity compared to the purebred parents. Maternal traits which need to be monitored and improved include fertility and calf survivability.

Growth of Brahman progeny (pure and crossbred) was similar to that of the best genotypes, particularly at 18 months of age. However, the Feedlot performance of this progeny was poor and similar to that of the indigenous Sanga breeds. Carcass qualities, namely eye muscle area and intra-muscular fat, were also poor. However, only a feedlot system of finishing was evaluated and this may not be suited to all genotypes, particularly late maturing breeds.