News and updates on research on livestock value chains by the International Livestock Research Institute and partners

Monday, January 17, 2011

No more guesswork: Tool developed for better prediction of live weights of local pigs in western Kenya

Pig farmers in rural western Kenya can now have better bargaining power and a chance of getting a fair price when selling their animals, thanks to a newly developed tool that uses body length and girth measurements to estimate pig weight within reasonable levels of accuracy.

A study published in the January/February 2011 edition of the Journal of Swine Health and Production details how the weight-prediction tool was developed and validated based on 298 observations of pigs in Busia and Kakamega districts of western Kenya where smallholder pig keeping is a popular enterprise.

Households here typically keep one or two pigs of local nondescript breeds that are either tethered or left free to scavenge for feed.

No formal market structures exist for sale of the mature pigs; local traders and pork butchers usually travel between farms on bicycles looking for pigs to buy.

The selling price is based on the weight of the pig but because farmers cannot afford to buy weighing scales, they have no option but to guess the weight based on visual assessment.

This guesswork method of "weighing by looking" is evidently less accurate than the use of a scale and often results in the farmers underestimating the weight of their pigs and thus selling at a price far below market value.

Weight predictions using body measurements have been studied in other countries and for various species of animals.

However, this was the first time that weight prediction using girth and length measurements for pigs was being studied in rural western Kenya or in similar settings in East Africa.

Based on weights and body measurements, mathematical weight equations were developed for three categories of pigs: young (under 5 months), market age (5.1-9.9 months) and breeding age (over 10 months).

Farmers were also asked to "guesstimate" the age and weight of the pigs in each category.

The weight predicted by the equation was more accurate than that estimated by the farmers.

For 90% of the market-age pigs, the difference between the actual weight and that predicted by the equation was 4.6 kg which was significantly lower than the difference of 24 kg between the actual pig weight and the farmers' estimates.

The authors suggest that the weight-prediction tool will offer smallholder farmers in western Kenya the opportunity to get better market value for their local pigs and will act as an incentive to better manage their pigs through improved feeding and husbandry.

Separate analysis is ongoing to evaluate the effect of the tool on the farmer-trader bargaining process and on pricing.

The study was part of research by the lead author, Florence Mutua, towards a PhD degree in epidemiology from the University of Nairobi (awarded 2010).

The paper’s co-authors are Cate Dewey of the University of Guelph, Samuel Arimi and William Ogara of the University of Nairobi, and Esther Schelling of the Swiss Tropical and Public Health Institute.

Dr Mutua’s ILRI supervisor was Dr Thomas Randolph, agricultural economist and head of ILRI’s research team on smallholder competitiveness in changing markets.

Access the article

Mutua FK, Dewey CE, Arimi SM, Schelling E and Ogara WO. 2011. Prediction of live body weight using length and girth measurements for pigs in rural Western Kenya. Journal of Swine Health and Production 19(1): 26-33.

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