Breed Information
The Mashona, a Sanga type cow of South-central Africa, has developed over thousands of years to be thoroughly adapted to the local environment. Their resistance to high temperature, ticks and flies, and their ability to maintain reproductive efficiency in the semi-arid African climate have molded their unique characteristics.
In 1941 Messrs Wiloughby and Macleod began selection of suitable stock from the then tribal trust lands which rapidly expanded to 18 breeding farms and research stations. Strict selection for functional traits has stabilized and refined the Mashona into a beautiful, productive animal which has been thoroughly proven by research.
Hardiness, fertility and a significant degree of disease resistance are the result of centuries of natural selection under arduous African conditions. Starting with this foundation of exceptionally well-adapted cattle, the Mashona Cattle Society has applied advanced breeding methods such as herd performance testing, central and on-farm bull testing, use of reference sires and most recently the introduction of a nucleus breeding herd to improve the breed.
Excellent cow fertility and calf productivity are characterized by an early sexual maturity with a short anestrous period and a high calving percentage under harsh conditions. There are minimal calving difficulties resulting in maximum output per cow mass and per grazing area.
They have very low maintenance requirements and are highly mobile, selective grazers who also have the ability to browse. The Mashona has an early carcass maturity and a high dressing percentage. Minimal management is required due to their beneficial herd behavior of well developed herd instincts and maternal protection and their docile temperament which allows easy handling.
The most meaningful way of measuring the efficiency of beef production is not in terms of the size of the cow, size of the calf or even size of the slaughter steers — it is in terms of pounds (kg) of calf per pound (kg) of cow.
Fertility and Reproductive Performance of the Mashona Cow
Puberty or sexual maturity, is normally measured as the age at which the first behavioral estrous (heat) occurs, and can be confirmed by measuring the levels of the hormone progesterone in blood serum.
Many trials have shown that age at puberty in heifers can be markedly influenced by their plane of nutrition, and this was confirmed in Mashona heifers by Tiffin's work at Makoholi. This work and other trials also served to illustrate the considerable degree of genetic variation in age at puberty which exists within the Mashona breed.
Moreover, individual heifer data from Makoholi studies indicate that puberty can be obtained at ages as low as 362 days and body masses of 328 lbs (149kg) (Tiffin, 1989 — private communication), thus classifying the Mashona as an early sexually-maturing breed. No data are available for young bulls, but it can be assumed that they will also become sexually competent at a relatively young age. The practical significance of this work is that Mashona heifers can be effectively mated at 15 months of age as long as the plane of nutrition provides for sufficient growth and body mass. Although conception can occur at body masses below 397 lbs (180kg), it would appear that a body mass of 518 lbs (235kg), which represents approximately 70% of mature cow mass in the Makoholi herd, is a safe target mass to ensure high conception rates under ranching conditions.
Follow-up studies highlighted the fact that, due to body size and condition, calving at two years of age tended to lead to a reconception problem after the first calf. However, when estimated total weaned calf production in the first five years was compared for cows calving at either two or three years of age, productivity was higher in the earlier calving group.
This undoubtedly explains the markedly higher response of the ovaries in Afrikaner cows to standard injections of Follicle Stimulating Hormone when compared with Mashonas, and probably contributes to the higher incidence of 'silent' heats in Afrikaner cows which have been recorded in comparative trials. Overall, these data lend support to the concept that the relatively high fertility of Mashona cows may be associated with inherently different levels of endocrine function when compared with less fertile breeds.
Gestation Length
The limited evidence for Mashona cattle indicates that gestation length is within the normal range, but may tend to be slightly longer than the average for Bos taurus breeds. However, data from 306 observations for heifers inseminated in the Matopos Cross- breeding Project showed that the average gestation length for pure Mashonas (282.4 days) was slightly less than the average for all genotypes (284.2 days).
Calving Percentage
That the Mashona cow is relatively highly-fertile and can consistently produce a calf each year is born out by many studies carried out throughout Southern Africa in different environments. Recent data from the comprehensive Matopos cross-breeding trial over a seven-year period has confirmed these findings and illustrated the superiority of the Mashona cow when compared with the other pure breeds on the trial in terms of calving and weaning percentage.
Components of Reproduction
Work at Henderson Research Station has concentrated on attempts to describe why the Mashona appears to be relatively highly fertile, and as a model, Mashona cows have been compared with Afrikaner cows under similar conditions of management. In a series of trials, the period of post- partum anestrous has been shown to be considerably shorter in Mashonas than in Afrikaners. Mashona cows also appeared to be more sensitive than Afrikaners to the effect of the temporary interruption of suckling on the stimulation of estrus during the post-partum period. Moreover, it was found that in animals in which normal cyclic sexual activity had been restored after calving, the levels of progesterone in peripheral blood were higher in Mashonas when compared with Afrikaner cows. This undoubtedly explains the markedly higher response of the ovaries in Afrikaner cows to standard injections of Follicle Stimulating Hormone when compared with Mashonas, and probably contributes to the higher incidence of ‘silent’ heats in Afrikaner cows which have been recorded in comparative trials. Overall, these data lend support to the concept that the relatively high fertility of Mashona cows may be associated with inherently different levels of endocrine function when compared with less fertile breeds. Of particular interest in this respect was a trial in which groups of dry Afrikaner and Mashona cows, which were assessed visually to be in similar body condition, were subjected to chronic indernutrition similar to that which might occur during winter on poor range. The Afrikaner cows stopped cyclic sexual activity after losing a mean of 19 per cent of their initial body mass, whereas the Mashona cows lost a mean 32.5 percent of their initial body mass before sexual activity ceased. Estimates of percentage body fat in the cows, determined by tritiated water techniques, at the time that the Afrikaners became anestrous did not differ to any extent between breeds. Hence the greater ability of the Mashona cow to continue sexual activity during undernutrition cannot be attributed solely to an ability to maintain body condition.
Finally, some behavioral studies at Makoholi showed that, in contrast to some Bos indicus and Sanga breeds which exhibit very short and 'shy' heat periods, this was not the case in Mashonas. Signs of estrus were relatively clear and intense, and standing heat generally lasted for 3 to 5 hours.
Manipulation of Reproduction
Over the years Mashona cows have been involved in trials designed to improve fertility, with particular reference to individuals with sub-optimum reproductive performance. These have included the manipulation of weaning, the use of Human Chorionic Gonadotropin (HCG) during the post-insemination period in synchronized cows, suppression of prolaction by treatment with Bromocryptine, treatment with Naloxone and assessment of B-carotene levels.
With the exception of temporary and partial weaning, none of these trials led to the development of practical techniques.
It is noteworthy that the first development work on synchronized breeding in Zimbabwe was carried out on Mashona cattle at Henderson Research Station using prostaglandin. Subsequent trials have been designed to try and improve conception rates to insemination at the synchronized estrus.
Dystocia
There is no evidence to contradict the generally-held view that calving ease is an attribute of the Sanga breeds, including the Mashona. In Phase 1 of the Matopos cross-breeding work, the number of calvings needing assistance at birth as a percentage of number of calves born to heifers rose from 3.4% in purebred matings, to 4.3%, 8.0% and 13.3% when the Mashona heifers were mated to Afrikaner, Sussex and Charolais bulls respectively. This increase clearly reflected an effect of the size of sire breed contributing to an increase in the birth-mass of calves relative to cow mass at parturition. Moreover, of all the purebred matings in Phase 1, Mashona showed the lowest percentage of calving difficulty after the Brahman, which is renowned for producing calves of relatively low birth mass.
When, in Phase II, heifers were deliberately exposed to small sires, the incidence of dystocia was negligible (Tawonezvi, 1989 — private communication)
All the above information was taken from The Mashona Cattle of Zimbabwe, edited and compiled by Dr. D. H. Holness.
Mashona Cattle of Zimbabwe
Edited and compiled by Dr. D.H. Holness
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