Martha Olivera

Effects of polyunsaturated fatty acids from plant oils and algae on milk fat yield and composition are associated with mammary lipogenic and SREBF1 gene expression

The main aim of the present study was to examine the effects of long-term supplementing diets with saturated or unprotected polyunsaturated fatty acids from two different plant oils rich in either n-3 or n-6 fatty acids (FAs) plus docosahexaenoic acid (DHA)-rich algae on mammary gene expression and milk fat composition in lactating dairy cows. Gene expression was determined from mammary tissue and milk epithelial cells. Eighteen primiparous German Holstein dairy cows in mid-lactation were randomly assigned into three dietary treatments that consist of silage-based diets supplemented with rumen-stable fractionated palm fat (SAT; 3.1% of the basal diet dry matter, DM), or a mixture of linseed oil (2.7% of the basal diet DM) plus DHA-rich algae (LINA; 0.4% of the basal diet DM) or a mixture of sunflower oil (2.7% of the basal diet DM) plus DHA-rich algae (SUNA; 0.4% of the basal diet DM), for a period of 10 weeks. At the end of the experimental period, the cows were slaughtered and mammary tissues were collected to study the gene expression of lipogenic enzymes. During the last week, the milk yield and composition were determined, and milk was collected for FA measurements and the isolation of milk purified mammary epithelial cells (MECs). Supplementation with plant oils and DHA-rich algae resulted in milk fat depression (MFD; yield and percentage). The secretion of de novo FAs in the milk was reduced, whereas the secretion of trans-10,cis-12-CLA and DHA were increased. These changes in FA secretions were associated in mammary tissue with a joint down-regulation of mammary lipogenic enzyme gene expression (stearoyl-CoA desaturase, SCD1; FA synthase, FASN) and expression of the regulatory element binding transcription factor (SREBF1), whereas no effect was observed on lipoprotein lipase (LPL) and glycerol-3-phosphate acyltransferase 1, mitochondrial (GPAM). A positive relationship between mammary SCD1 and SREBF1 mRNA abundances was observed, suggesting a similar regulation for these genes. Such data on mammary gene expression in lactating cows presenting MFD contribute to strengthen the molecular mechanisms that govern milk fat synthesis in the mammary glands. In purified MEC, the dietary treatments had no effect on gene expressions. Differences between mammary tissue and milk purified MEC gene expression were attributed to the effect of lipid supplements on the number of milk purified MEC and its RNA quality, which are determinant factors for the analysis of gene expression using milk cells.

Dietary fatty acid intervention of lactating cows simultaneously affects lipid profiles of meat and milk.

BACKGROUND The present study investigated tissue-specific responses of muscle and mammary gland to a 10 week intervention of German Holstein cows (n = 18) with three different dietary fat supplements (saturated fat; linseed oil or sunflower oil plus docosahexaenoic acid-rich algae) by analysing fatty acid profiles and quality parameters of meat and milk. RESULTS Plant oil/algae intervention affected neither fat content nor quality parameters of meat but decreased fat content and saturated fatty acid amounts of milk. Linseed oil/algae intervention caused significantly higher concentrations of C18:3n-3 (meat, 1.0 g per 100 g; milk, 1.2 g per 100 g) and C22:6n-3 (meat, 0.3 g per 100 g; milk, 0.14 g per 100 g). Sunflower oil/algae intervention increased n-6 fatty acid contents in milk (4.0 g per 100 g) but not in meat. Elevated amounts of C18:1trans isomers and C18:1trans-11 were found in meat and especially in milk of plant oil/algae-fed cows. C18:1cis-9 amounts were found to be increased in milk but decreased in meat after plant oil/algae intervention. CONCLUSION The present study demonstrated that dietary fatty acid manipulation substantially shifted the fatty acid profiles of milk and to a lesser extent of meat, whereas meat quality traits were not affected. Indications of tissue-specific responses of mammary gland and muscle were identified.

Identificación por PCR de Brucella canis en sangre y leche canina. Reporte de un caso

Canine brucellosis is a disease caused by Brucella canis that is associated to reproductive problems in dogs, and it is also known as zoonosis. These bacteri...

Calidad higiénica y sanitaria de leche cruda acopiada en diferentes regiones colombianas

The results of hygienic and sanitary quality tests on 705,210,165 litres of raw milk collected by a Colombian dairy company in 2010 were analysed. This milk was sent from 3,939 cooling tanks in11 storage centreson the savannah around Bogota, the Middle Magdalena Valley, the Viejo Caldas region, the Antioquia department and on the Atlantic coast. Significant differences (p<0.01) were found between plants for average colony forming units (CFU) and somatic cell count(SCC)using non parametric Kruskal Wallis one-way analysis of variance (ANOVA). The Funza (19,000), Armenia (63,000) and San Pedro (68,000) storage centres had lower average CFU/ml counts whilst the Puerto Boyaca (354,000), Funza (364,000) and Planeta Rica centres (373,000)had lower SCC/ml. 93.90% of the milk samples exceeded national CFU count standards and 84.49% of them the pertinent international standards. 39.54% of the milk sampled complied with Regulated Control Scheme (RCS) international standards. No significant differences were found in CFU and SCC values due to the time of year and a low level of association was found between the values for both parameters (r2=0.43). Ascertaining limitations regarding milk quality standards /failure to comply with the min each Colombian dairy region will help to orientate further education programmes for farmers according to their particular needs and thereby lead to improving Colombian milk quality.

Survey of gastrointestinal parasites, liver flukes and lungworm in feces from dairy cattle in the high tropics of Antioquia, Colombia

A cross sectional study was undertaken to determine the prevalence and intensity of parasitic infections in dairy cattle in the high tropics of Colombia. A total of 1003 rectal samples were collected from dairy cows at 29 farms between May and June 2014 to represent the number of farms, age groups, and size of the 65,000-cow population in the municipality of San Pedro de los Milagros. Coprological techniques were used to detect gastrointestinal nematodes, liver flukes, coccidian oocysts, and first larval stage counts of Dictyocaulus viviparus. In order of decreasing prevalence, the following parasites were detected: coccidial oocyst (36.7%; 95% CIs, 31.6–42.7), strongyle nematodes (31.6%, 27.8–35.4), liver flukes (30.9%, 21.5–37.5), cestodes (8.4%, 7.1–9.7), and D. viviparus (5.4%, 3.4–7.5). Co-infections by all possible combinations of the three most predominant groups occurred in 11 to 15% of the animals. There were significant differences in infection rates between age groups, with higher risk of liver fluke infection in animals older than 1 year of age (odds ratio (OR) = 3.2), but lower presence for coccidia and strongyles (OR = 0.19 and 0.51, respectively). For Fasciola hepatica, within-herd prevalences of > 25% in 16 farms and 94 of 281 (33.5%) animals with > 5 eggs per gram (epg) indicate that significant production losses are likely occurring. The variation in the prevalence of gastrointestinal parasites and liver flukes, together with the level of infection among age groups, could be used in integrated management programs to establish selective anthelmintic treatments and select for heritable traits of host resistance. These results serve as a baseline for future studies to determine the success of control measures and should increase awareness that subclinical parasitism is widespread in the livestock sector.