Comparison of Some Nonlinear Functions for Describing Broiler Growth Curves of Cobb500 Strain

This study was conducted to compare some nonlinear functions to describe the broiler growth curve of the Cobb500 strain. A flock of fifty one-day-old chicks were randomly selected from a henhouse of 2500 chicks. Our goal was to establish a growth curve using weighting data using mathematical solutions of time-dependent differential functions. In total, six equations were subjected to a statistical calibration by a sequential quadratic programming under the non-linear regression procedure of the SPSS program. The results showed that the heterogeneity rate between individuals of the same batch increases with the age of the chicks, from more than 10% an early age to less than 30% at the slaughter age. The goodness of fit for six dynamic models showed that the number of iterations required increases with the number of parameters of the model. However, the three parameter models were the best model for describing growth curve (the greatest efficiencies and the lowest error components). The asymptomatic values ​​(3500g to 7500g) and their estimation errors (2% to 12%) are relatively acceptable for the three-parameter models compared to those of four parameters (more than 8000g and up to 100% error). Finally, the comparison between actual and predicted values by models shows that the Gompertz model was the most suitable till up to the four weeks of age. After 1 month of age, the Gompertz has a lower precision and the logistics, Von Bertalonffy and WLS models accurately described the growth curve

Warmer Weather Linked to Tick Attack and Emergence of Severe Rickettsioses

The impact of climate on the vector behaviour of the worldwide dog tick Rhipicephalus sanguineus is a cause of concern. This tick is a vector for life-threatening organisms including Rickettsia rickettsii, the agent of Rocky Mountain spotted fever, R. conorii, the agent of Mediterranean spotted fever, and the ubiquitous emerging pathogen R. massiliae. A focus of spotted fever was investigated in France in May 2007. Blood and tissue samples from two patients were tested. An entomological survey was organised with the study of climatic conditions. An experimental model was designed to test the affinity of Rh. sanguineus for biting humans in variable temperature conditions. Serological and/or molecular tools confirmed that one patient was infected by R. conorii, whereas the other was infected by R. massiliae. Dense populations of Rh. sanguineus were found. They were infected with new genotypes of clonal populations of either R. conorii (24/133; 18%) or R. massiliae (13/133; 10%). April 2007 was the warmest since 1950, with summer-like temperatures. We show herein that the human affinity of Rh. sanguineus was increased in warmer temperatures. In addition to the originality of theses cases (ophthalmic involvements, the second reported case of R. massiliae infection), we provide evidence that this cluster of cases was related to a warming-mediated increase in the aggressiveness of Rh. sanguineus, leading to increased human attacks. From a global perspective, we predict that as a result of globalisation and warming, more pathogens transmitted by the brown dog tick may emerge in the future

Relationship between body condition score, body weight, some nutritional metabolites changes in blood and reproduction in Algerian Montbeliad cows

The objective of this study was to investigate through a nutritional and biochemical approach the variability of reproductive performance in dairy cows of semi arid area herds. Seventy four multiparous females reared in four farms were tracked from one month before calving to the third month postpartum. Information about reproductive events were taken once a month, and the body condition score evaluated on a 1 to 5 scale according to the EDMONSON method (1989). Blood samples were taken on a sample of 23 cows chosen according to body condition score before calving for biochemical analysis of energy, nitrogen and minerals parameters. Maximum concentrations depended to physiological stage. Blood glucose and calcium are stable at around 0.60g / l and 0.76 g / l respectively (p>0.05). Uremia (0.27g/l vs 0.16g/l) and triglycerides (0.74g/l vs 0.48g/l) are higher in the first month of lactation (p <0.05). Cholesterol (1.42g/l vs 1.03g/l) is higher in the 3rd month post-partum. The results show also that best performances are recorded in cows with BC before calving around 3 and 3.5 (p<0.05) and for those loosing less BC in the first months postpartum. The nutritional and metabolic profiles of females were used to characterize high female performance which has a reduces format and losses of BC in post-partum are minimal and late; They express the moderate concentration of glucose (0.60g / l), elevated cholesterol (> 1.20 g / l) and low triglycerides (about 0.60 g / l). Great format Cows with early and significant loss of BC after calving. They express a poor reproductive performance with high triglycerides concentration (1.02 g / l) in the 1st month of lactation. [Vet. World 2011; 4(10.000): 461-466

Ecology and fishery of the deep-water shrimp, Aristeus antennatus (Risso, 1816) off Algeria (south-western Mediterranean)

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Common epidemiology of Rickettsia felis infection and malaria, Africa

This study aimed to compare the epidemiology of Rickettsia felis infection and malaria in France, North Africa, and sub-Saharan Africa and to identify a common vector. Blood specimens from 3,122 febrile patients and from 500 nonfebrile persons were analyzed for R. felis and Plasmodium spp. We observed a significant linear trend (p<0.0001) of increasing risk for R. felis infection. The risks were lowest in France, Tunisia, and Algeria (1%), and highest in rural Senegal (15%). Co-infections with R. felis and Plasmodium spp. and occurrences of R. felis relapses or reinfections were identified. This study demonstrates a correlation between malaria and R. felis infection regarding geographic distribution, seasonality, asymptomatic infections, and a potential vector. R. felis infection should be suspected in these geographical areas where malaria is endemic. Doxycycline chemoprophylaxis against malaria in travelers to sub-Saharan Africa also protects against rickettsioses; thus, empirical treatment strategies for febrile illness for travelers and residents in sub-Saharan Africa may require reevaluation