Comparison of mathematical models applied to f1 dairy sheep lactations in organic farm and environmental factors affecting lactation curve parameter.

THE OBJECTIVE OF THIS STUDY WAS TO COMPARE THE GOODNESS OF FIT OF FOUR LACTATION CURVE MODELS: Wood's Gamma model (WD), Wilmink (WL), and Pollott's multiplicative two (POL2) and three parameters (POL3) and to determine the environmental factors affecting the complete lactation curve of F1 dairy sheep under organic management. A total of 5,382 weekly milk yields records from 150 ewes, under organic management were used. Residual mean square (RMS), determination coefficients (R(2)), and correlation (r) analysis were used as an indicator of goodness of fit for each model. WL model best fitted the lactation curves as indicated by the lower RMS values (0.019), followed by WD (0.023), POL2 (0.025) and POL3 (0.029). The four models provided total milk yield (TMY) estimations that were highly correlated (0.93 to 0.97) with observed TMY (89.9 kg). The four models under estimated peak yield (PY), whereas POL2 and POL3 gave nearer peak time lactation estimations. Ewes lambing in autumn had higher TMY and showed a typical curve shape. Higher TMY were recorded in second and third lambing. Season of lambing, number of lambing and type of lambing had a great influenced over TMY shaping the complete lactation curve of F1 dairy sheep. In general terms WL model showed the best fit to the F1 dairy sheep lactation curve under organic management.

Sheep management and cryptosporidiosis in central Mexico.

To establish the association between sheep farm management practices and cryptosporidiosis in Central Mexico, 37 farms were invited and questionnaires answered by owners. Faeces samples were taken from lambs under 3 months old and ewes in the farms. Parasites were identified by modified Ziehl-Neelsen stain. Questionnaire included: general farm information, facilities characteristics, facilities cleaning measures, water use and farm and animal management practices. Farms were grouped in a low ( Pound 3,37%), medium (3.38-49.9%) and high basis ((3)50%) according to prevalence. Associations (OR) were calculated according to positivity, compared by chi-square test. A general prevalence of 34,33% was found. Five variables showed statistical significance (p<0.05). Associations found were: use of bed, grazing place, and bottle cleaning. The only association found between management practices and cryptosporidiosis that could represent a risk was the grazing place. This report is the first one in the country regarding predisposing conditions for cryptosporidiosis.

Prevalence of Cryptosporidium spp. in asymptomatic sheep in family flocks from Mexico State.

To determine Cryptosporidium spp. prevalence in faeces from asymptomatic sheep, 37 family flocks in Mexico State were sampled. Data were collected by the interview method and Ziehl-Neelsen stain of faecal samples for Cryptosporidium identification. The independent group proportion hypothesis test was used for differences in prevalences between sheep farms. A 34.3% general prevalence was found, and prevalence in herds with >100 animals was significantly higher (40.6%). Correlation was found between flock size and Cryptosporidium spp. presence (odds ratio, OR, 2.57; confidence interval, IC(95%), 1.84-3.60).

[Bibliometric repercussions of adopting English as the sole language for publication]. / Repercusión bibliométrica de adoptar el inglés como idioma único de publicación.

OBJECTIVE: To determine the effect that the change from French to English had on the impact of the Annales de l' Institut Pasteur. THEORETICAL REFERENCE: The Pasteur Institute journals have a prestige of over 100 years of existence and eight Nobel Prize winners in Physiology and Medicine. Changes through time on the impact of these journals can be monitored as they are included in databases of the ISI (Institute for Scientific Information). METHODS: A year by year analysis from 1974 to 1992 was done using simple regression between percentage of articles published in English and: a) their impact factor; b) their ranking among journals of the same field. RESULTS: The determination coefficient (r2) between the percentage in English and the impact factor was 0.108, and that between percentage in English and the journal's rank in similar publications was 0.178 for the Ann Microbiol, 0.045 for the Ann Immunol and 0.122 for the Ann Virol. CONCLUSIONS: The change of language did not increase the impact factor of the French journals.