PubMed · 3175627
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M S Gordon. 1988-10-07. Ecological physiology.. https://doi.org/10.1126/science.3175627
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A prospective observational study was conducted among smallholder dairy farmers in Murang'a District, Kenya, to estimate the incidence of Theileria parva infections, as well as calf morbidity and mortality caused by the infection. The study was conducted between March 1995 and August 1996, in five cohorts of female calves from birth to six months of age from different agro-ecological zones (AEZs) and grazing-system strata shown previously to have varying prevalences of T. parva infection. A total of 188 smallholder dairy farms with 225 female calves were selected purposively by five AEZ-grazing strata. All recruited calves were visited within the first two weeks of life and thereafter at biweekly intervals up to the age of six months. The mean number of cattle in these smallholder farms was 2.6. Both exotic and indigenous breeds of cattle and their crosses were present, with the former predominating. The incidence (27-54%) of sero-conversion to T. parva in an ELISA test was significantly different (p < 0.05) across the five AEZ-grazing strata and increased with lower elevation and unrestricted grazing. Calf morbidity and mortality were also variable across the AEZ-grazing strata. East Coast fever (ECF) was the highest-incidence cause calf morbidity and mortality (relative to other diseases). There are great differences in the epidemiology of ECF within a small area and this implies that there is need to carefully consider different ECF control strategies in different AEZ-grazing strata.
Milk urea nitrogen (MUN), together with percentage milk protein (PROT), are increasingly used as indicators of the protein-energy balance and for monitoring nutrition and diagnosing feeding disorders. The goal of this study was to analyze the effects of parity, milk yield, days in lactation, somatic-cell count, and herd and feeding factors on MUN and PROT. In 10 dairy herds, one milk sample was taken from each of 418 cows, within +/- 2 days of the routine milk-test visit. We used a four-step multiple linear-regression model with backward elimination, including interactions between herd and the different factors. For both dependent variables, there were significant interactions with herd. Herd-specific models were markedly different; however, the daily amount of protein concentrates fed remained (and had a positive coefficient) in seven of 10 herd models for MUN. This factor is easy to record under field conditions and has to be considered in the evaluation of the ration by means of MUN and PROT. Overfeeding of rumen soluble protein can be easily diagnosed and corrected using MUN analyses. The relationships between MUN and PROT in respect of the factors parity, daily milk yield, and days postpartum also vary considerably among herds.
OBJECTIVE: To determine the effect of within-farm variability in the number of females mated per week during a 1-year period on annual breeding herd productivity in swine breeding herds and to apply statistical process control charts to measures of within-farm variability. DESIGN: Longitudinal study. SAMPLE POPULATION: 84 swine farms with a female inventory of 390 to 1,491 sows and gilts (mean, 761 females). PROCEDURE: As a measure of within-farm variability in a breeding herd, SD for the number of females mated per week during a 1-year period was evaluated. Two types of production records for 84 farms were evaluated. One file contained within-farm variability (SD) in mated females for each farm, and the second included annual productivity 19 weeks after week of mating. We also defined forewarning limits as mean +/- 2 SD, using a statistical process control chart. RESULTS: Larger within-farm variability in number of mated females was associated with lower annual measurements, such as fewer pigs weaned per mated female per year and lower farrowing rate. In addition, farms that did not have any weeks outside the forewarning limits for number of mated females produced more pigs weaned per mated female per year than those with 1 or more weeks of over- or underproduction. Furthermore, the number of weeks outside of forewarning limits was positively associated with within-farm variability in number of mated females. CLINICAL IMPLICATIONS: We recommend that farm managers determine a target range for the number of females mated per week to prevent large week-to-week variations in breeding herd operations.