Introduction
Asela station
Cattle
Herd management
Data recording
Asela station was established in 1967/68 in the Chilalo District of the Arsi Region of Ethiopia (Figure 1). It was designed as a component of the Chilalo Agricultural Development Unit (CADU), an integrated project established jointly by the Ethiopian and Swedish Governments. The activities of CADU have been expanded since 1975 and are currently part of the Arsi Rural Development Unit (ARDU). The investigations analysed and reported here were set up with the objectives of:
1. Comparing the important performance traits of indigenous, crossbred and high grade dairy cattle on the station.
2. Measuring the environmental influences (years, seasons, etc) on dairy production traits.
3. Deriving relevant dairy productivity indices for the various breed types.
4. Assessing the initial performance of these crossbred cattle under smallholder dairy farming conditions in the surrounding areas.
Preliminary results from the breeding work at Asela station and with nearby smallholders have been reported by Brannang et al (1980), Schaar et al (1981), and Swensson et al (1981). However, detailed assessment of the overall productivity of crossbred and high grade animals under station and smallholder dairy farming conditions has hitherto not been made.
The Arsi Region covers 24 500 km², or 2% of the total area of Ethiopia. Cultivated land comprises 20.4%, forest land 3.9%, pasture land 9.8%, and fallow and waste land 65.9% of the region. The region varies in altitude and the cropping patterns include both highland and lowland crops. The major crops are barley, wheat, pulses and oil crops, teff, maize and sorghum, in that order. The human population is estimated at 1.34 million, and at 54 per km² is relatively high compared with other Ethiopian regions. Livestock are a major agricultural resource, there being 1.5 million cattle, 0.97 million sheep and goats, and 0.32 million draught animals.
Asela is situated about 180 km southeast of Addis Ababa in a highland plateau region rising to a height of 2000-3000 m. Both Arsi Region and Asela station are characterized by mild subtropical weather with maximum and minimum temperatures ranging from 18° to 28°C and 5° to 10°C respectively. The station experiences bimodal rainfall, with an annual average precipitation of 1300 to 1350 mm. Short rains occur during March and April, followed by long rains during July to September. The long dry season lasts from November to February, and a short dry spell is experienced in May and June. The average distribution of rainfall at Asela station is illustrated in Figure 2. Precipitation and altitude rather than temperature are generally considered to be the most important factors determining vegetation conditions. The vegetation consists of annual legumes and perennial grass species. The natural pastures include Chloris gayana, Setaria sphacelata, Panicum coloratum and a number of useful legumes such as Trifolium semipilosum, Glycine wightii and Trifolium burchellianum. Asela station, and Chilalo District in general, are characterized by a rather mild climate with few livestock production problems from external parasites such as ticks and flies. In this area, formerly recognized as cattle country, farming activities are gradually switching to cropping.
Crossbreeding with introduced breeds started at Asela in 1967/68 with the objective of producing F1 heifers consisting of ½ Bos indicus and ½ Bos taurus germplasm. The F1 would later be upgraded to produce varying levels of Bos taurus inheritance (CADU 1970). The original plan was to use germplasm from the Jersey and Friesian breeds on the local Arsi type. It was also intended that other local breed types, such as the Fogera, Barca and Boran, would be incorporated into the scheme. However, the use of Jersey semen from Kenya was discontinued in 1970, when it was found that the F1 progeny had small teats which were inconvenient for milking. Farmers also preferred, and asked for, the larger sized F1 Friesian crosses. The indigenous foundation cows were purchased from local markets. They included 200 Arsi, 22 Fogera, 16 Barca and 10 Boran cows. These together with some others kept at the nearby Gobe station provided the basic stock for crossbreeding. Due to the demand for crossbred cattle from farmers, 40 Friesian x Boran crosses were imported from Kenya to supplement the project. The Arsi, Boran, Fogera and Barca were later upgraded to the 50%, 75% and 87.5% Friesian levels. The Jersey-based F1 crosses were upgraded to Friesian germplasm only.
Figure 1. Arsi Region and Chilalo District of Ethiopia.
Newly purchased local heifers were restricted in quarantine for a period of at least 3 weeks. They were checked for disease and were put on liberal feeding regimes based on pasture, hay and concentrates. After entering the breeding herd, animals continued to be grazed on pasture, and during the dry season hay or concentrates were fed. A number of short-term trials were carried out at various times on calf and cow feeding for growth and milk production. These provided guidelines for the proper management of dairy cattle under Ethiopian conditions, and the results were reported by Schaar et al (1981). The Arsi cows in these trials received concentrates for 4 months before parturition. After parturition they were supplemented at a rate of 0, 0.5 or 1.1 kg per kg of milk yield. The crossbred heifers received concentrates for 2 months before parturition and were then supplemented with 0, 0.25 or 0.5 kg per kg of milk. Different levels of concentrate feeding were discontinued after the first lactation. Thus, during the second and later lactations concentrates consisting of 48% Niger seed cake (residue of Guizotia abyssinica after oil extraction), 48% wheat bran, 3.5% bonemeal and 0.5% salt were fed to all animals at a rate of 2 to 4 kg per cow per day depending on the level of milk yield.
Cows were hand milked twice daily during the first 4 years until machine milking equipment was installed in 1972. Arsi cows, however, continued to be milked by hand and without their calves at foot, while crossbreds were gradually started on machine milking.
Newborn calves were taken away from their dams shortly after birth. They were bucket fed to weaning, which occurred at between 49 and 79 days. Colostrum and whole milk substitutes were fed to calves twice daily at the rate of 1.0 kg to 2.5 kg of milk equivalent per day. Animals were routinely vaccinated against anthrax, rinderpest, blackleg and pleuropneumonia. Regular dosing against internal parasites and measures against mastitis were undertaken. All crossbred calves were vaccinated against brucellosis, using S19 vaccine. Culling among the local Arsi breed was mostly based on very short lactations that exhibited milk letdown interference and poor temperament.
All animals purchased were assigned individual eartag numbers. At each calving, the date, sire number, breed, sex, colour, weight and individual number of the calf were recorded. All abortions were noted. Body weights were taken at birth, puberty and after each parturition. Milk recording was initially carried out daily, but in 1973 was changed to either twice monthly or once every 3 weeks. Butterfat testing was also carried out on each milk yield recording day. Vaccinations and treatments against identified ailments were recorded. No individual supplementary feeding records were kept, except for the animals in feeding trials.
Figure 2. Mean monthly rainfall at Asela station, 1968-1977.
