Cattle are deemed infertile when they are neither normally fertile nor completely sterile.

Experts note that interest in bovine infertility increased with the introduction of artificial insemination in the 1950s and as the factors involved became known to farmers, herdsmen physiologists and other workers took a keen interest in studying the same.

Experts say the causes of infertility are many and can be complex.

They relate to the final stage of an ovary where ovulation, fertilization, implantation and the development and delivery of the foetus and its membranes.

Anything interfering with these routines, such as diseases, poor nutrition, inadequate herd management, hereditary and congenital factors, hormonal disturbances or environmental changes, makes the animal infertile, if only temporarily.

Infertility and pregnancy challenges in cows in Uganda are primarily driven by a combination of inadequate nutrition, high prevalence of infectious diseases, poor management practices particularly regarding artificial insemination and environmental stress.

In many cases, these factors cause long calving intervals, repeat breeding and silent heats. 

In a study conducted by scientists from Makerere University department of Veterinary Surgery and Reproduction led by the late Dr Lawrence Miyingo Kezimbira about the topic age at puberty in Nganda cattle under traditional conditions in Uganda, they give details as published in International Atomic Energy Agency.

Research process

Research into the reproductive efficiency of Nganda cattle was carried out in a study by scientists where they determine whether delayed puberty was a serious problem in Zebu cattle species commonly known as Nganda heifers.

The team selected 60 Nganda heifers and their crosses with the other local types and monitored its ovarian activity to establish their ovary formation process.

The results indicated that over 50% started cycling at about 2.5 years of age with nearly 90% of the heifers beginning their sexual activity by 3 years of age.

To test whether the age at puberty could be reduced by supplementary feeding and control of internal and external parasites, 20 Nganda heifers 1.5 years old were selected in the second part of the study.

The results proved that supplementary feeding, deworming and spraying against parasites had a positive influence on the initiation of sexual activity in pubertal Nganda heifers.

Indigenous breeds of cattle in the tropics and subtropics exhibit poor fertility, late sexual maturity, low conception rates, long calving intervals and poor weaning rates compared with high breeds maintained in northern Europe and North America.

In order to try and improve this situation, it is necessary to study each breed in its prevailing environment so as to identify the limiting factors and thereafter to design a practical scheme of improvement.

The level of management and the availability of feed resources affect the performance of any breed of cattle.

Management of cattle

In Uganda there are two main ways in which indigenous cattle are managed.

Small scale farmers keep an average of about ten adult cows. They do not have fenced land but graze their animals along roadsides

Farmers in more remote areas of the countryside in typical cattle areas such as parts of Masaka and Ankole have larger herds of 30-2000 animals.

Most of these farmers have fenced farms, although a few cattle owners still move from place to place grazing their herds.

These medium to large scale farmers milk their animals only once in the morning and the calves are left to run together with the dams so that they suckle all day.

At night the calves are housed although supplementation is not usually practised.

Most of the small and large scale farmers deworm the un-weaned calves at least twice. Older calves and adult cattle are very rarely dewormed, especially in large herds, owing to the expense. Most farmers in Uganda today control parasites by the use of acaricides.

Disease and feed management

Prophylactic treatment against trypanosomiasis is often given and control of other diseases depends on the effort of each farmer.

The government enforces some compulsory vaccinations, such as for rinderpest, foot and mouth disease and contagious bovine pleuropneumonia.

It is unfortunate that there is as yet no harvesting of excess pastures as hay or silage during the rainy seasons.

Hay and silage could maximize production during the dry periods when green grass is scarce. Concentrate feeding is not a common practice; animal performance could probably be increased with such supplements.

The pastures available in Uganda include a mixture of grass species and legumes mainly established naturally.

There are only a few areas where pastures have been planted and  they include types of grasses commonly found are Pennisetum purpureum, Pennisetum clandestinum, Chloris guyana, Panicum maximum, Themeda trianda, Hyparrhenia rufa, Hyparrhenia filipendula, Setaria incrassata, Chrysopagon auchen, Digitaria scalarum and Brachria spp.

Reproduction of animals and infertility challenges

There are only two reports on the reproductive function of indigenous cattle of Uganda.

These identified, through abattoir studies, the abnormalities that could cause infertility.

However, clinical field investigations have been lacking and similarly there is no information available on endocrine status.

The present study was therefore designed to provide some of this information.

The study aimed to define the approximate age of puberty and first pregnancy in Nganda cattle under typical small scale management conditions.

What was considered most is the weight of heifers at puberty; the weight of calves at parturition and the incidence of infertility in cycling females, pregnancy loss and neonatal survival.

The influence of pasture quality, parasites and the incidence of brucellosis in lactating animals is another factor

The second part of the study examined whether supplementary feeding, deworming against internal parasites and spraying against parasites had a positive effect on the age at puberty, cycle regularity, cycle length and the intensity of heat sign.

Results

Since two independent studies were performed to investigate the reproductive efficiency of the Nganda cattle.

The resultson 63 year old Nganda heifers indicated that they could be categorized into three groups, active open heifers, pregnant heifers and inactive heifers.

The active heifers were those with large ovaries. Their uterine horns had good tone.

Most of the active and pregnant heifers had a good body score.

The inactive heifers were those which revealed small, smooth ovaries with no follicular development and small, toneless uteri.

These had a poor to moderate body condition and in all, 51.7% of the heifers were pregnant at first palpation.

During the subsequent observation period of one year, all the 22 heifers initially diagnosed as active and open conceived.

However from this group 2 heifers aborted at 3 months and 8 months of gestation, respectively.

Another heifer from the initially pregnant group also aborted at 4 months of gestation and the owner blamed the bull for having caused the abortion since he saw it serving the pregnant heifer.

Part two the study indicated that supplementation, deworming and spraying had a positive effect on the reproductive performance of Nganda cattle.

In conclusion it can be stated that delayed commencement of sexual activity is still a problem in Nganda type cattle.

The extent of the problem is, however, far less than with other indigenous types such as the Ankole, Nkedi and Nkolomojo.

Good management involving the provision of feed supplements, maintaining small herds and offering treatment against worms, parasites and debilitating diseases such as trypanosomiasis accounts for the relatively early sexual maturity in Nganda cattle.

Study comparison

Scientists from University of Nebraska Lincolin found out that while several factors can play into a herd’s reproductive success, management is usually the key factors.

The study which was published in the French post dwelled on solutions which include concentration on nutrition ratio given to the cows to avoid infertility.

Dr Mary Drewnoski, beef and forage specialist from University of Nebraska is quoted saying Protein or energy are usually the big rocks that are missing, especially in young animals that may still be growing

She advised farmers to ensure that Heifers and cows should be an increasing plan of nutrition during the breeding season as established throughout the year.

Bull power and breeding

Farmers must know that females are just part of the equation in that bull management is key and must ensure that there are enough bulls in the herd.

Bulls should be tested four to six weeks prior to turn out and bulls may be infertile.

This is because the sperm production is a 61-day process, so injuries that occur earlier in the course of the year may not show up during a Breeding Soundness Exam, if the exam is done too early.

Young animals which are still growing need to be fed well for them to perform. Farmers must ensure the cows have good body weight because most thin cows tend to be infertile.

Other nutrients

Farmers must ensure that they provide animals diets comprising of Vitamin A and phosphorous including minerals.

Infections

It is important for farmers to keep disease infection out of the herd and this can be done by vaccinating the animals by veterinary doctor.