A live weight–heart girth relationship for accurate dosing of east African shorthorn zebu cattle

Maia Lesosky,Ilana Conradie,Ian Graham Handel,Barend Mark de Clare Bronsvoort,Sarah Dumas,Amy Jennings,Samuel Thumbi,Phillip Toye

doi:10.1007/s11250-012-0220-3

Abstract

The accurate estimation of livestock weights is important for many aspects of livestock management including nutrition, production and appropriate dosing of pharmaceuticals. Subtherapeutic dosing has been shown to accelerate pathogen resistance which can have subsequent widespread impacts. There are a number of published models for the prediction of live weight from morphometric measurements of cattle, but many of these models use measurements difficult to gather and include complicated age, size and gender stratification. In this paper, we use data from the Infectious Diseases of East Africa calf cohort study and additional data collected at local markets in western Kenya to develop a simple model based on heart girth circumference to predict live weight of east African shorthorn zebu (SHZ) cattle. SHZ cattle are widespread throughout eastern and southern Africa and are economically important multipurpose animals. We demonstrate model accuracy by splitting the data into training and validation subsets and comparing fitted and predicted values. The final model is weight0.262 = 0.95 + 0.022 × girth which has an R 2 value of 0.98 and 95 % prediction intervals that fall within the ±20 % body weight error band regarded as acceptable when dosing livestock. This model provides a highly reliable and accurate method for predicting weights of SHZ cattle using a single heart girth measurement which can be easily obtained with a tape measure in the field setting.

Highlights

The accurate estimation of livestock weights is important for many purposes such as determining ration amounts, agreeing on sale prices and for ensuring the correct therapeutic dosing of animals
East African shorthorn zebu (SHZ) are multipurpose animals that serve as sources of draught power, milk and meat and contribute to household incomes throughout eastern and southern Africa (Rege et al 2001)
Milk production is largely determined by reproductive performance, which is in turn closely correlated with cow weight

Summary

Introduction

The accurate estimation of livestock weights is important for many purposes such as determining ration amounts, agreeing on sale prices and for ensuring the correct therapeutic dosing of animals. The relationship between live weight and capacity for work in SHZ used as draught animals is well established (Bartholomew et al 1994; Fall et al 1997). It can be deduced that body weight can be used to evaluate the value of an animal intended for use as breeding stock, milk production, draught power or beef. A simple, accurate method of approximating SHZ body weight in the field will give farmers greater bargaining authority at cattle markets, maximising the economic return on the investments made in their animals

Methods

Results

Conclusion