Farmers' Perceptions of the Impacts of Tsetse and Trypanosomosis Control on Livestock Production: Evidence from Southern Burkina Faso

Interviews with all the households in the Agropastoral Zone (ZAP) of Yalé, southern Burkina Faso, were conducted in 1994 and again in 1997 to assess the impacts of a tsetse control programme implemented from 1994, using insecticide-impregnated targets and pour-on treatments of all cattle with deltamethrin 1%. In the absence of health and productivity monitoring, data were collected in single-visit surveys in order to generate quantitative estimates of relevant reproductive performance variables for cattle and to assess changes in the inputs used and outputs produced. The results indicate a 25% increase in herd size and an increase in the number of oxen from 0.1 to 1.1 per household; a reduction in mortality from 63.1% to 7.1% and reductions in the rates of abortions and stillbirth of 55.9% and 51.3%, respectively; and an increase in the rate of live births of 57.6% and in the milk yield from 0.2 to 2.2 litres/cow per day in the dry season. These results show the dramatic impacts that trypanosomosis control can have on Zebu cattle exposed to high tsetse challenge. Well-designed surveys can be a cost-effective way to obtain estimates of productivity impacts that can be used to simulate projections of herd growth and meat and milk production in herd models. While there are many confounding factors associated with farmers' perception of a gain in productivity, these estimates form a useful alternative to subjective assessments in modelling the economic benefits of tsetse and trypanosomosis control.     

Performance of Djallonké Sheep under an Extensive System of Production in Faranah,Guinea

A total of 147 ewes, 4 rams and 188 lambs of their progeny of the Djallonké breed of sheep were used to study the factors affecting reproductive and growth traits and the causes of lamb mortality. Data on ewes were collected during a 12-month period, while those on the lambs born to 123 of the ewes were collected until they were 12 months of age. The average fertility and abortion rates were 0.84 and 0.09. The fertility rate increased and the abortion rate decreased with increasing age of the ewes (p<0.05). The number of lambs born per ewe joined, litter weight at birth per ewe joined and litter weight at weaning per ewe joined were 1.28, 3.5 kg and 17 kg, respectively. The average numbers of lambs born per ewe, lambs born alive per ewe, lambs born dead per ewe and lambs per ewe that died between birth and weaning were 1.53, 1.43, 0.03 and 0.3, respectively. The age of the ewes significantly (p<0.05) affected all these traits except the number of dead lambs and the index of fertility (94%). The age of the ewes significantly (p<0.05) affected the birth weight and the weight at 6 and 12 months of age, whereas the lambing season significantly (p<0.05) affected all the growth traits studied. The type of birth was the most important source of variation in body weights of lambs. Sex had no significant (p>0.05) effect on the growth traits studied. The complex `starvation–bad management–light body weight at birth' caused 48% of the lamb mortality between birth and weaning, while diarrhoea, pneumonia and internal and external parasites caused approximately 52% of the lamb mortality over the same period. The seasonal raw mortality rate of the lambs before weaning was highest in the humid season.     

Vertebral Fractures in Newborn Calves

A prospective study on vertebral fractures in newborn calves is described. Vertebral fractures were found in 7.0% of necropsied calves of the Danish Holstein-Friesian (SDM) and Red Danish Dairy (RDM) breeds. Cases were not found in submitted calves of the Jersey breed or beef breeds. At least in beef breeds this was probably due to the low number necropsied. The rate of vertebral fractures in SDM and RDM breeds and between males and females were similar. Most cases occurred in calves born by heifers, and manual traction force had been applied in all cases. All fractures which in most cases consisted of a simple epiphysiolysis were located at the thoraco-lumbar area, and especially the posterior epiphysis of T13 was afflicted.     

Black walnut curculio: patterns of nut damage in a plantation environment

Data on curculio-caused nut mortality have been collected since 1985 to assess the impact of this nut predator on black walnut trees grown in a plantation environment. These data have been analyzed to investigate spatial and temporal patterns of curculio damage. Curculio damage was independent of nut cluster height or cardinal direction within the crowns of young, nut-bearing black walnut trees, and was greater in parts of a walnut planting that bordered a stand of native hardwoods than in a part remote from the stand. Nut losses caused by the curculio were consistently higher in an upland versus a bottomland planting, although the differences were not significant during most years of the study. Nut mortality caused by the curculio differed among years of the study and was negatively correlated with annual nut abundance.Contribution from the Missouri Agricultural Experiment Station, Journal Series No 12, 156.     

Longevity of longfinned eels Anguilla dieffenbachii in a New Zealand high country lake

A sample of 146 longfinned eels (Anguilla dieffenbachii), ranging in length from 231–1203 mm, was collected from Lake Rotoiti, Nelson Lakes National Park, New Zealand. Otoliths (n= 114) of eels were difficult to read, mainly due to the considerable age (maximum age 106 years). Growth rate was slow and linear, averaging 9 mm. year^?1. These are the slowest growth rate and maximum age from any study of Anguilla spp. to date. Lakes within National Parks provide the largest commercially unfished waters within New Zealand and hence provide reserve breeding stocks of longfinned eels; however, the average generation time of 93 years for female eels from Lake Rotoiti implies that stock management should be conservative.     

利用变动系数求林分平方平均直径的株数累积百分数

对于直径遵从正态分布的同龄纯林 ,通常只从经验上判定其平方平均直径在株数累积分布曲线上的位置介于 5 5 %～ 6 4%之间 .该文从林分算术平均直径 ( d) ,林分平方平均直径 (Dg)和直径变动系数 (c)三者之间的数学关系 ,导出f(c) =1+c2 - 1 c是正态分布的分布函数的自变量 ,并从数学上证明了其Dg 的株数累积百分数的范围在 5 4%～ 5 6 8%之间 ,同时介绍了用Excel中Normsdist函数求解Dg 株数累积百分数的方法 ,并用一组数据进行验证 ,计算结果与实际情况吻合 ,可靠性 95 %以上 .     

Reproduction and Mortality in a Colony of Captive Greater Cane Rats,Thryonomys swinderianus,Temminck

The reproductive performance and mortalities in a colony of captive greater cane rats, Thryonomys swinderianus, were monitored from 1992 to 1998 at the Grasscutter Domestication Centre, Achimota, Ghana. The animals were kept in cages and exposed to constant lighting from a 100 W electric light bulb during the night. The diet consisted mainly of freshly cut Panicum maximum (guinea grass) fed ad libitum, with occasional supplements of cassava and cane sugar. The results indicate that the mean litter size and litter weight were 2.9±0.51 and 439.4±81.23 g, respectively. These figures are low compared to those reported elsewhere. However, the mean birth weight was 151.2±11.08 g, higher by 12% than previously reported values. It is considered that poor nutrition, excessive exposure to light and stress were responsible for the relatively poor reproductive performance reported in these animals. The main causes of death were traumatic injuries (32%) and pulmonary congestion (16%).     

Machine learning classification procedure for selecting SNPs in genomic selection: application to early mortality in broilers

Summary Genome‐wide association studies using single nucleotide polymorphisms (SNPs) can identify genetic variants related to complex traits. Typically thousands of SNPs are genotyped, whereas the number of phenotypes for which there is genomic information may be smaller. When predicting phenotypes, options for statistical model building range from incorporating all possible markers into the specification to including only sets of relevant SNPs (features). In the latter case, an efficient method of selecting influential features is required. A two‐step feature selection method for binary traits was developed, which consisted of filtering (using information gain), and wrapping (using naïve Bayesian classification). The filter reduces the large number of SNPs to a much smaller size, to facilitate the wrapper step. As the procedure is tailored for discrete outcomes, an approach based on discretization of phenotypic values was developed, to enable feature selection in a classification framework. The method was applied to chick mortality rates (0–14 days of age) on progeny from 201 sires in a commercial broiler line, with the goal of identifying SNPs (over 5000) related to progeny mortality. To mimic a case–control study, sires were clustered into two groups, low and high, according to two arbitrarily chosen mortality rate cut points. By varying these thresholds, 11 different ‘case–control’ samples were formed, and the SNP selection procedure was applied to each sample. To compare the 11 sets of chosen SNPs, predicted residual sum of squares (PRESS) from a linear model was used. The two‐step method improved naïve Bayesian classification accuracy over the case without feature selection (from around 50 to above 90% without and with feature selection in each case–control sample). The best case–control group (63 sires above or below the thresholds) had the smallest PRESS statistic among groups with model p‐values below 0.003. The 17 SNPs selected using this group accounted for 31% of the variation in raw mortality rates between sire families.     

Effects of temperature and continuous and interrupted wetness on the infection of pear leaves by conidia of Venturia nashicola

Experiments were conducted to determine: (i) the effects of temperature and duration of continuous wet periods on the infection of pear seedlings by conidia of Venturia nashicola , the causal agent of pear scab; and (ii) the effects of the length and temperature of dry interrupting periods on the mortality of infecting conidia. Average number of scab lesions per leaf increased with increasing duration of wetness. Logistic models adequately described the change in the average number of scab lesions per leaf at 5, 10, 15, 20 and 25°C over the wetness duration. At 30°C, only a few lesions developed. Simple polynomial models satisfactorily described the relationship of the three logistic model parameters (maximum number of lesions, rate of appearance and the time to 50% of the maximum number of lesions) with temperature. The optimum temperature for infection was found to be approximately 20°C. The relationship between mortality and the length of a dry period interrupting an infection process can be satisfactorily described by an exponential model. The rate of mortality at 10, 16 and 22°C did not differ significantly, but was significantly less than that at 28°C.     

Effects of Scavenging on Diet Selection and Performance of Rhode Island Red and Fayoumi Breeds of Chicken Offered a Choice of Energy and Protein Feeds

An experiment was conducted to evaluate the effect of scavenging on diet selection and the comparative performance of Rhode Island Red and Fayoumi breeds of chicken. The breeds were compared under three feeding/management regimes: (1) a choice of ground noug cake and cracked maize, with confinement; (2) a choice of ground noug cake and cracked maize, but being allowed to scavenge for about 6 h; and (3) a commercial layer mash, with confinement. Scavenging did not change the pattern of diet selection. About 90% of the daily intake of both the confined and scavenging birds under choice feeding comprised maize. The efficiency of feed utilization and nutrient intake were also similar in these groups. The Fayoumi were more efficient in terms of feed conversion, although the egg production performance of the two breeds did not vary significantly. Scavenging hens had a significantly lower egg production than the birds under confinement offered a choice of feeds. Scavenging significantly increased the mortality in both breeds. In conclusion, scavenging affected the performance adversely and, despite the provision of a choice of feed providing a source of energy and protein, both the scavenging and confined birds on choice feeding failed to eat sufficient to meet their protein requirements.