The distribution of conjugated linoleic acid (CLA) in dairy products commercially available in Chile is poorly understood. This study aimed to assess the content of CLA in dairy cow products from Chile and the effect of processing fresh milk into dairy products. Samples of raw milk were categorized into two groups based on the animal feeding system utilized by the dairy farm: 1) grazing based systems (Los Lagos region); and 2) housing systems using total mixed ration (TMR) diets (Los Angeles region). Simultaneously, commercial samples of condensed milk, powdered milk, butter and Gouda cheese were analyzed. Furthermore, samples of raw milk and processed products (powdered and sweetened condensed milk) were also analyzed. Dairy farms based on grazing systems had higher levels of CLA in raw milk than TMR farms. In addition, average values of CLA were 1.72 g 100 g −1 of total fatty acids, in spring milk in the Los Lagos region, and 0.42 g 100 g −1 in summer milk, in the Los Angeles region. Similarly, the CLA content of dairy products was higher than that of raw milk. Milk processing affected the transferring of CLA from fresh milk into the final products. Sweetened condensed milk presented lower CLA values than raw and powdered milk. In conclusion, this study indicates the importance of the production systems to the CLA content as well as the effects of milk processing into dairy products. To sum up, more research is needed to elucidate the exact effect of the processing conditions of dairy products on the CLA content.

At present, there is limited and contradictory information about the effects of the use of canola (Brassica napus) seed as supplement on the contents of conjugated linoleic acid (CLA) in milk of grazing cows. The objective of this study was to evaluate the effect of a dietary supplement with canola seed on the production and composition of milk, and CLA concentration in Chilean Black Friesian cows under pasture conditions. Three experiments were done. Experiment 1: control group was fed 5 kg d -1 of commercial concentrate without canola (0-TC1) and treatment group that was fed 3.75 kg of commercial concentrate plus 1.16 kg of whole canola seed (1.16-TC1). Experiment 2: Control group was fed 8 kg d -1 commercial concentrate without canola (0-TC2) and treatment group that was fed 6.2 kg of commercial concentrate plus 1.2 kg of ground canola seed (1.2-TC2). Experiment 3: control group was fed 6 kg d -1 commercial concentrate without canola (0-TC3) and treatment group was fed 6 kg of commercial concentrate with 20% of whole canola seed (1.2 kg d -1 , 1.2-TC3). The duration of each experiment was 60 days. No differences in milk production and quality were observed among the experimental groups in every assay. The CLA isomers trans-10, cis-12 and cis-10, cis-12 were higher than those normally found in the scientific literature. There was no effect of the inclusion of canola seed on total CLA content or the content of cis-9, trans-11, trans-10, cis-12 and cis-10, cis-12 isomers.

El objetivo de este estudio fue comparar el impacto productivo (kg día -1 de leche por vaca), calidad nutricional (cantidad de grasa y proteína) y microbiológica (RCS) de la leche, en un rebaño lechero que pasó de una ordeña convencional a una robotizada, con sistemas de alimentación en base a pradera. Se utilizaron datos de 12 meses para cada sistema, 2017 para la ordeña convencional y 2018 para la ordeña robotizada. Se obtuvieron datos del control lechero para el ordeño convencional y del equipo de ordeña marca Lely Astronaut A4 para el ordeño robotizado. Los datos fueron sometidos a un análisis comparativo a través prueba de t de student. El sistema robotizado presentó significativamente (p > 0,05) una mayor producción de leche (24,18 ± 2,76 L) y de grasa (4,12 ± 0,34 %) en relación a la ordeña convencional (22,62 ± 4,16 L y 4,03 ± 0,39 % de grasa). Por otro lado el RCS fue significativamente mayor (p > 0,05) en la ordeña robotizada (221,56 ± 62,96 × 10 3 células ml -1 ) en relación a la convencional (213,56 ± 94,88 × 10 3 células ml -1 ).