Survival of Listeria monocytogenes during manufacture, ripening and storage of soft lactic cheese made from raw goat milk.

Soft lactic cheeses were manufactured with raw goat milk inoculated with Listeria monocytogenes. The physico-chemical and microbiological characteristics of curds and cheeses were determined after each processing step as well as during ripening and refrigerated storage. The fate of Listeria monocytogenes was evaluated by enumeration on PALCAM agar and by a qualitative detection after a double selective enrichment procedure. The results showed that the physico-chemical and microbiological characteristics of lactic cheeses caused a decrease of Listeria monocytogenes counts. However, this decrease did not lead to the complete disappearance of the pathogen and Listeria monocytogenes was able to survive in soft lactic cheeses made with raw goat milk.

Effects of the initial level of milk production and of the dietary protein intake on the course of natural nematode infection in dairy goats.

The level of dietary protein is known to alter the establishment and the pathophysiology of gastrointestinal nematodes in sheep. On the other hand, high-producing dairy goats are less resistant and/or resilient than low-producing ones to experimental nematode infection. During a 2-year study, we have investigated the course of a natural nematode infection (mainly T. colubriformis) in a high-producing dairy goat flock. In year 1, 50 grazing goats divided in high (HP) or low producer (LP) were compared from April to October for parasitological and milk parameters. In year 2, the 25 HP goats were only considered and were allocated to two levels of dietary protein, high level (HPr) with a protein coverage of 125% or normal level (NPr) with a protein coverage of 106%. They were monitored as above. In year 1, HP goats showed a greater nematode egg output (1856 vs. 1000epg) associated with higher values in T. colubriformis IgG in autumn than LP ones whereas the decrease in serum phosphate concentration was similar in both groups. In year 2, HPr goats exhibited lower egg output in autumn (2219 vs. 2817) vs. NPr ones. Moreover, milk yield and fat content were significantly higher in HPr vs. NPr in the 2nd part of the study. HP goats are less resistant to nematode infection in natural conditions. Resistance and resilience of HP goats may partially be improved by a protein supplementation in the diet.