Komba, Gabriel Luke2016-05-022020-01-072016-05-022020-01-071982Komba, G. L. (1982) Crossbreeding pigs in Tanzania, Masters dissertation, University of Dar es Salaam. Available at http://41.86.178.3/internetserver3.1.2/detail.aspxhttp://localhost:8080/xmlui/handle/123456789/42Available in print form, East Africana Collection, Dr. Wilbert Chagula Library, Class mark (THS WRE TD365.J67)The high demand for animal protein in the developing countries raises the need for making deliberate efforts to improve and expand the livestock production industry. In Tanzania, for example, with a pig population of 80,000 and where pig meat is becoming popular in non-Islamic communities, per capital meat intake can be substantially increased by exploring and improving the pig industry. Crossbreeding is considered the fastest method of improving through breeding most of the economic traits in market pigs. Response to crossbreeding depends on the combining ability of pig breeds. Lack of data to support crossbreeding programmes in the production of market pigs in Tanzania was a major reason for undertaking the study. The experiment was conducted between October 1980 and January 1982. The number of pigs varied with the parameters studied. Three boars and 14 gilts were analysed for fertility traits while 11 litters were used for studies on traits related to litter size. There were 98 pigs for birth weight and 92 pigs for waning weight studies. Other traits studied included growth rate and carcass quality and yield. The progeny belonged to Danish Landrace, Hampshire-Yorkshire and the three-breed reciprocal crosses of the three breeds. All pigs were reared and managed under the same environmental conditions. Crossbreeding had no effects on conception rates. Furrowing percentage was highly significant (p,0.001) for breed of dam and breed of sire. Gestation period ranged from 107-116 days and averaged 113.7 +2.5, 112.2+3.1 and 113+5+1.4 days for the three-breed reciprocal crossbred, Hampshire-Yorkshire and Danish Landrace litters, respectively. The mean litter size of the three-breed reciprocal crosses was lower by 14.2% at weaning than the averages of the parent purebred litters. This showed a negative heterosis for this trait. Crossbreeding significantly increased pig weigh at all ages, average daily gains and slightly improved pig viability. The overall mortality rate was 18.4% and was higher in Danish Landrace than in cross red pigs. Sow crushing and still births were the main causes of piglet mortality while piglet scours and helminthic infestations retarded their growths. Feed conversion ration was slightly improved by crossbreeding. Carcass composition traits were influenced differently by breed and sex. Dressing percentages of Danish Landrace, the three breed reciprocal crosses and Hampshire-Yorkshire pigs were 68.8%, 68.3% and 67.2%, respectively. Crossbreeding had significant effect (p,0.001) on back fat thickness and slight of lean while sex had significant influence (p,0.05) on internal fat deposition. Eye muscle area and hind and fore quarters were slightly affected by breed effects. Hampshire-Yorkshire pigs had significantly heavier head, shoulder and spare ribs-joints than the other two breed types. However, the three-breed reciprocal crossbreds had significantly heavier loin joint than the others. Sex significantly influenced chops meat-joint. Belly and ham meat joints and the internal organs were least affected by breed or sex. Proportions of lean and fat in the 12th rib sample joint were highly influenced (P<0.001) by breed and sex. Bone content was only slightly affected by crossbreeding. Under the conditions of the experiment, the three-breed crosses had higher survival rate and better growth performance than the purebreds and leaner carcasses than the two-breed crosses. The study has shown that the use of crossbred gilts has an advantage over the purebred gilts in the production of the three breed crosscossbred pigs.enSwine breedingThesis