Cattle Herd Size Research Articles

Application of modelling to determine the absence of foot-and-mouth disease in the face of a suspected incursion

AIM: To use disease modelling to inform a response team about the number of animals per herd/flock to be examined, and the start date and duration of clinical surveillance required to be confident that foot-and-mouth disease (FMD) was not present on an island in New Zealand with a population of approximately 1,600 cattle, 10,000 sheep and a small number of pigs, goats and alpacas. METHODS: Because the probability of detecting clinical disease in (the) primary case(s) in larger herds and flocks was extremely low, deterministic and stochastic mathematical SLIR (susceptible, latent, infectious, recovered) models for the transmission of infection were constructed to estimate the date when clinical lesions in herds and flocks would be detected with 95% confidence. Surveillance targeted the first wave of infections following a suspect index case. RESULTS: If 70 cattle in herds of about 400 cattle were examined it was estimated it would take approximately 13 (90% stochastic range 9–19) days from first exposure before it would be possible to achieve 95% confidence for detecting clinical signs for a low-virulence virus, and 9 (7–14) days for a high-virulence virus. The duration of sufficiently accurate clinical detection was 17 (15–19) days and 13 (12–14) days for low- and high-virulence viruses, respectively. A sample of 70 sheep from flocks of >1,000 would be required to achieve clinical detection at about the same time but with a shorter period of detection than for cattle. The duration of effective detection could be increased by examining a larger sample in most sheep flocks, however the small size of many cattle herds in the study population limited the confidence of detecting group-level disease in cattle, therefore necessitating repeated herd inspections. The model suggested that group-level detection was not feasible if it was based on elevated body temperature alone because of short durations of fever in infected animals. CONCLUSION AND CLINICAL RELEVANCE: Simulation modelling is a useful and powerful tool for informing ongoing surveillance activities in the face of an exotic disease incursion. Results of modelling suggested to start clinical inspection activities at 4 days and to continue regular inspection twice a week for about 35 days after the date of first exposure, to satisfy the required 95% confidence threshold of clinical detection of FMD in cattle herds and sheep flocks.

The effects of flock size, habitat type and cattle herd sizes on feeding and vigilance in cattle egrets (Ardeola ibis)

The effects of flock size, habitat type and cattle herd sizes on feeding and vigilance in cattle egrets <i>(Ardeola ibis)</i>

Elk Management Strategies and Profitability of Beef Cattle Ranches

Computer simulation was used to determine the effects of wild elk (Cervus elaphus) on available forage, cattle herd size, and ranch gross margin in southwestern Montana beef cow-calf production systems. Data collected from 5 southwestern Montana ranches were used to develop input parameters for bio-economic models of elk forage harvest and beef production. Input parameters described ranch resources, animal inventories, and animal management. Cattle herd size ranged from 241 to 1147 head. Elk numbers varied by season within ranch and ranged from 49 to 421 head. Ranches were simulated as currently managed with elk present and with 10, 20, 30, and 100% of the elk removed. Simulated management scenarios were replicated 10 times. Data from each ranch were analyzed by one-way analysis of variance. Cattle herd size, gross margin, and available forage significantly (P < 0.05) increased when all elk were removed; however, the magnitude of these effects differed among ranches. Removal of all elk permitted cattle herd size to increase from 7 to 32% across ranches. Annual costs of elk on the 5 ranches (i.e., increase in gross margin from elk removal) ranged from $5,949 to $21,152. On an AUM basis, elk costs ranged from $8.55 to $14.51. Three management alternatives were evaluated for their potential to recover elk costs: Montana's Block Management Program, coordinated exchange of forage use, and leasing of hunting access. For each ranch, at least one of these management strategies could recover all estimated costs of providing elk habitat. Elk can significantly reduce profits for cow-calf ranches in southwestern Montana. Elk impacts on beef enterprise profits are closely associated with efficiency of resource use by cattie-i.e., ranches with lower unit costs of production lose more gross margin by providing forage for elk compared to ranches with higher production costs. DOI:10.2458/azu_jrm_v55i2_torstenson

Elk management strategies and profitability of beef cattle ranches

Computer simulation was used to determine the effects of wild elk (Cervus elaphus) on available forage, cattle herd size, and ranch gross margin in southwestern Montana beef cow-calf production systems. Data collected from 5 southwestern Montana ranches were used to develop input parameters for bio-economic models of elk forage harvest and beef production. Input parameters described ranch resources, animal inventories, and animal management. Cattle herd size ranged from 241 to 1147 head. Elk numbers varied by season within ranch and ranged from 49 to 421 head. Ranches were simulated as currently managed with elk present and with 10, 20, 30, and 100% of the elk removed. Simulated management scenarios were replicated 10 times. Data from each ranch were analyzed by one-way analysis of variance. Cattle herd size, gross margin, and available forage significantly (P &lt; 0.05) increased when all elk were removed; however, the magnitude of these effects differed among ranches. Removal of all elk permitted cattle herd size to increase from 7 to 32% across ranches. Annual costs of elk on the 5 ranches (i.e., increase in gross margin from elk removal) ranged from 5,949 to 21,152. On an AUM basis, elk costs ranged from 8.55 to 14.51. Three management alternatives were evaluated for their potential to recover elk costs: Montana's Block Management Program, coordinated exchange of forage use, and leasing of hunting access. For each ranch, at least one of these management strategies could recover all estimated costs of providing elk habitat. Elk can significantly reduce profits for cow-calf ranches in southwestern Montana. Elk impacts on beef enterprise profits are closely associated with efficiency of resource use by cattie-i.e., ranches with lower unit costs of production lose more gross margin by providing forage for elk compared to ranches with higher production costs.

A survey on processing and marketing characteristics of peri-urban agropastoral Dairying in Ghana

A survey was conducted in five districts on the Accra plains to characterize the peri-urban dairy production system. Results from the survey indicated that farmers were keeping cattle, sheep, goats, and poultry (Guinea fowl, turkey, chicken, and duck), cattle being the only species milked. The mean flock size was 73.6 TLU with a coefficient of variation of 103 per cent. The average cattle herd size was 133. Farmers made limited use of agro-industrial by-products. Cultivation of pastures, improved fodder, and multipurpose trees was non-existent, and neither was any system of cut and carry practised. The use of concentrate and protein supplementation was also negligible. The mean length of the dry season was 5.2 1 0.7 months. Offtake was low at 8.9 per cent per annum. Replacement and calving rates were 0.7 and 0.67, respectively. The mean age at first calving and calving interval were 36 and 14.4 months, respectively. The mean lactation length was 8.5 months. There were no crossbreds of the type 'exotic W local'. The Sanga was the predominant breed of cattle and constituted over 76 per cent of cattle kept on the Accra plains. Feeding of calves was by suckling residual milk from dams after partial milking. Calves were allowed to suckle until the cow was nearly dry, leading to a long mean calf weaning age of 8.4 months. Cows were milked once daily usually in the mornings. The mean daily partial milk yield per cow was 1.55 1 0.22 l. Mean partial annual milk yield per farm was 10,040 1 2952 l. It was concluded that the system required substantial transfer of improved technologies to increase milk production. Ghana Jnl.agric. Sci Vol.32(1), 1999: 53-58

Estimated economics of theileriosis control in Africa

Theileriosis, caused by the parasite Theileria parva, leads to considerable economic losses in cattle in Burundi, Kenya, Malawi, Mozambique, Rwanda, Sudan, Tanzania, Uganda, Zaire, Zambia and Zimbabwe. These losses have hitherto not been comprehensively quantified. A computer spreadsheet model was used to estimate the losses and the benefits of theileriosis control by the infection and treatmentmethod of immunization in the region. The parameters of the model included national size and structure of cattle herds, the estimated impact of the disease in terms of incidence, case morbility and case fatality rates, and the effect of immunization on the disease. The total regional loss due to theileriosis in 1989 was estimated to be US$ 168 million, which includes as estimated mortality of 1.1 million catle. Previous economic analysis of immunization showed high economic returns, with a benefit: cost ratio in the range of 9–17. The input values and results presented were derived from calculations using data sources that are inadequate in content and quality, and hence should be interpreted with caution. When adequate data are available, the approach could be used to generate more accurate results for any study site, production system, country and the region as a whole.

An analysis of agricultural livestock and traditional crop production statistics as a function of total annual and early, mid and late rainy season rainfall in Botswana

Total rainfall amounts are usually not considered as useful indicators for agricultural season qualities because they do not reflect other parameters such as rainfall distribution, crop water requirements and soil moisture-holding capacities. Most methods that also take into account the above parameters have not been validated for Botswana because of the country's restricted meteorological network and because of the non-availability of the necessary soil data. Rainfall alone is, therefore, one of the most frequently used parameters in drought monitoring and quality assessments of agricultural seasons and provides essential, but rough information several months before the real agricultural production data have become available. In this paper, Botswana's national cattle herd size between 1965 and 1985, regional cattle death ratios and regional traditional crop production between 1979 and 1985 have been analysed as a function of total annual and early, mid and late rainy season rainfall as defined by Bhalotra (1985a). It was found that in Botswana, with marginal rainy season conditions both for cattle and crops, such an analysis can be used as a useful indicator for the agricultural quality of a rainy season. To obtain an indicator of the season quality for livestock performance, a weighted average for the past three seasons and for October December (early), January February (mid) and March-April (late) rainfall has to be used. A good indicator for the crop season quality can be obtained from a weighted average of early, mid and late rainfall of the actual season. These indicators cannot, however, be used as indices to forecast livestock condition or crop production, but only to carry out acceptable assessments of rainy season conditions on a subnational or areal scale.

Bride Wealth, an Alternate View

In this paper I view the amount of bride wealth paid as a distinct part of a larger bride wealth institution, and present an economic explanation for the variation in amount paid among the pastoralists of East Africa. Citing the importance of labor and nomadic movements to the size of pastoral cattle herds, the amount of bride wealth paid is seen as a function of these constraints. Statistical analysis of the data on bride wealth and nomadic pattern yields a nearly perfect cor relation supporting this view.