Factors influencing average milk yield of herds at two levels of production.
An experiment was started in 1950 designed to find out what proportion of the difference in milk yield between herds is genetic in origin. Sixty-five pairs of twins were split at birth equally between farms having high-yielding herds and farms having low-yielding herds. A previous paper on this experiment reported on the growth of the twins, the present paper on milk yield and on management practices in the herds. Twenty-four pairs of twins survived to complete one lactation and these provide an estimate of 24%±18% for the genetic part of the difference between the herds. Aspects of rearing of the twins and of management of the herds were examined. Twins in the high-yielding herds were served and calved earlier than those in the low-yielding group but they had a longer interval between service and calving. Differences between average heifer yields and average cow yields were from one-and-a-half to two times greater in the high- than in the low-yielding herd group. There were no obvious quantitative differences in feeding practice between the two groups although differences in body size suggest that twins in the high group were done better. For the age at first service there was a positive rank correlation of 0·30 between body size differences and subsequent differences in first lactation milk yield. There was no single factor of management or environment which appeared to be the cause of the yield difference between the herds.
INFLUENCE DU NUMÉRO DE LACTATION ET DU NIVEAU D'ÉTABLE SUR LA PRODUCTION LAITIÈRE DES VACHES MONTBÉLIARDES DU JURA
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. INFLUENCE DU NUMÉRO DE LACTATION ET DU NIVEAU D’ÉTABLE SUR LA PRODUCTION LAITIÈRE DES VACHES MONTBÉLIARDES DU JURA G. Ricordeau, P. Auriol, J. Lefebvre, M. Carpentier
Mite population density analysis of stored dried apricots in Turkey
The aim of this study was to determine the population density of mite species attacking stored dried apricots in Malatya, Elazig and Izmir regions of Turkey. Storage construction types and duration of storage were also considered. The samples were collected during 2000–2003 in the most important apricot producing areas (Malatya and Elazig) and the exporting center (Izmir). Frequency of occurrence and rates of intensity of infestations were determined (16.50% from Malatya, 3.19% from Elazig and 80.49% from Izmir). A total of 16 mite species belonging to 13 genera and 11 families were identified during the surveys. The pest species Carpoglyphus lactis (L.) (Astigmata: Carpoglyphidae) was the most abundant species recorded (69.14% of samples). The highest infestation value recorded was 15,534 mites per kg.