**2. Materials and methods**

A longitudinal study involving growth data collection from Ankole, Friesian, Friesian cross, Boran and Boran crosses was conducted. Growth data on-station and on-farm from the experimental animals was collected over a period of three years (July 2006 to June 2009) and 9 months from October 2008 to June 2009 respectively.

The on farm study was conducted in the districts of Kiruhura, Ibanda and Sembabule. In Kiruhura district, the sub-counties of Kikatsi and Sanga were involved. In Ibanda district, Nyabuhikye and Kikenkye sub-counties were involved. In Sembabule the studies were conducted in Lugusulu and Migwala sub-counties.

On-station the studies were conducted at Mbarara Zonal Agriculture Research and Development Institute (ZARDI) found in Mbarara district. It involved taking bi- weekly (i.e. fortnightly) weights using the heart girth tape. The heart girth tape was graduated in both cm and kg. Both measurements were taken but for purposes of analysis, only weight values were used. There was a high and positive correlation between heart girth and body weight of cattle (Oluka, 2006). Individual study animals were identified using the ear tag numbers for effective continuous monitoring. Animals were restrained in the crush and weighed using the heart girth tape.

The sample sizes varied from district to district. In Kiruhura district, the study animals were 141, Ibanda district, 182 and in Sembabule district 189. Calves below the age of three months were identified and randomly selected and tagged for the study. Only farmers who were willing to participate in the study were recruited and involved in the study. The farmers willingly gave the number of animals requested for the study. More Female animals were preferred because they were normally kept for longer periods by the farmers and were not easily sold. In contrast the male were sold off at any age to meet the financial needs of the farmers e.g. paying school fees, meet family health care needs or provide food.

Under on-station management, a total of 30 Ankole cattle and 35 Friesian cattle were recruited for the study. Unlike the on-farm cattle, parameter measurement and data collection started immediately after birth of calves by taking and recording birth weights and there after bi-weekly.

The heart girth tape was placed around the girth for reading off the weights. Weights of cattle were immediately recorded in data sheets and transferred for entry into Excel programme as back up and for further collation for analysis; all weights in kilograms (kg) were entered in Excel worksheet
