Influence of organic systems on Stearoyl-CoA desaturase gene expression in goat milk

Diet supplementation with hemp (Cannabis sativa L.) inflorescences: effects on quanti-qualitative milk yield and fatty acid profile on grazing dairy goats

Hemp (Cannabis sativa L.) is an annual plant belonging to the family of Cannabaceae with several varieties characterized by different fatty acid profile, content in flavonoids, polyphenols, and cannabinoid compounds. Hemp is mostly used in livestock nutrition as oil or as protein cake, but not as inflorescences. The aim of this study was to evaluate the effect of dietary hemp inflorescences on milk yield and composition in grazing dairy goats. Twenty Camosciata delle Alpi goats at their 3rd parity and with a mean body weight of 45.2 ± 2.0 kg, immediately after kidding, were equally allocated into two groups (G: Grazing and GH: grazing and hemp). For three months, all goats were fed on a permanent pasture and received 700/head/day of concentrate; diet of group GH was supplemented with 20 g/head/day of hemp inflorescences. Goats' body weight did not change during the trial. Individual milk yield was daily recorded and samples collected every 20 days for chemical composition and fatty acid profile analysis. No significant differences were found for milk yield and chemical composition. Caproic (C6:0) (1.80 vs. 1.74%; p < 0.01) and lauric acids (C12:0) were significantly higher in milk of group GH (4.83 vs. 4.32%; p < 0.01) as well as linoleic (C18:2) (2.04 vs. 1.93%; p < 0.05), adrenic acid (C22:4) (0.046 vs. 0.031%, p < 0.05), omega-6/omega-3 ratio (3.17 vs. 2.93, p < 0.05) and total conjugated linoleic acids (CLAs) (0.435 vs. 0.417%; p < 0.01). The results of this study suggest that the supplementation of grazing goats' diet with hemp inflorescences may enhance the milk nutritional characteristics by increasing its content of CLAs and other beneficial fatty acids.

Genome-Wide Association Study of Milk Composition in Karachai Goats

This study is first to perform a genome-wide association study (GWAS) to investigate the milk quality traits in Karachai goats. The objective of the study was to identify candidate genes associated with milk composition traits based on the identification and subsequent analysis of all possible SNPs, both genome-wide (high-confidence) and suggestive (subthreshold significance). To estimate the milk components, 22 traits were determined, including several types of fatty acids. DNA was extracted from ear tissue or blood samples. A total of 167 Karachai goats were genotyped using an Illumina GoatSNP53K BeadChip panel (Illumina Inc., San Diego, CA, USA). Overall, we identified 167 highly significant and subthreshold SNPs associated with the milk components of Karachai goats. A total of 10 SNPs were located within protein-coding genes and 33 SNPs in close proximity to them (±0.2 Mb). The largest number of genome-wide significant SNPs was found on chromosomes 2 and 8 and some of them were associated with several traits. The greatest number of genome-wide significant SNPs was identified for crude protein and lactose (6), and the smallest number-only 1 SNP-for freezing point depression. No SNPs were identified for monounsaturated and polyunsaturated fatty acids. Functional annotation of all 43 SNPs allowed us to identify 66 significant candidate genes on chromosomes 1, 2, 3, 4, 5, 8, 10, 13, 16, 18, 21, 23, 25, 26, and 27. We considered these genes potential DNA markers of the fatty acid composition of Karachai goat milk. Also, we found 12 genes that had a polygenic effect: most of them were simultaneously associated with the dry matter content and fatty acids (METTL, SLC1A 8, PHACTR1, FMO2, ECI1, PGP, ABCA3, AMDHD2). Our results suggest that the genes identified in our study affecting the milk components in Karachai goats differed from those identified in other breeds of dairy goats.

Characterization and Authentication of “Ricotta” Whey Cheeses through GC-FID Analysis of Fatty Acid Profile and Chemometrics

The fatty acid (FA) profiles of 240 samples of ricotta whey cheese made from sheep, goat, cow, or water buffalo milk were analyzed by gas-chromatography (GC). Then, sequential preprocessing through orthogonalization (SPORT) was used in order to classify samples according to the nature of the milk they were made from. This strategy achieved excellent results, correctly classifying 77 (out of 80) validation samples. Eventually, since 36 (over 114) sheep ricotta whey cheeses were PDO products, a second classification problem, finalizing the discrimination of PDO and Non-PDO dairies, was faced. In this case, two classifiers were used, SPORT and soft independent modelling by class analogy (SIMCA). Both approaches provided more than satisfying results; in fact, SPORT properly assigned 63 (of 65) test samples, whereas the SIMCA model accepted 14 PDO individuals over 15 (93.3% sensitivity) and correctly rejected all the other samples (100.0% specificity). In conclusion, all the tested approaches resulted as suitable for the two fixed purposes. Eventually, variable importance in projection (VIP) analysis was used to understand which FAs characterize the different categories of ricotta. Among the 22 analyzed compounds, about 10 are considered the most relevant for the solution of the investigated problems.

The Italian Cilentana goat breed: productive performances and economic perspectives of goat farming in marginal areas

In the internal areas of Cilento, province of Salerno (Campania), the Cilentana, a small native goat breed population, is reared quite widespread, due to its dual-purpose attitude and to its typical productions. The extensive livestock system adopted for this breed allows the use of otherwise abandoned territories and a sustainable farming capable of ensuring high-quality levels. In addition, Cilentana goat farming represents an important source of income for the local communities and also preserves the territory itself guaranteeing the protection of biodiversity and the conservation of local activities that have a historical tradition. The aim of this study is twofold: give an overview of Cilentana breed morphological and productive traits linked to the historical and gastronomic tradition of the area and emphasize the economic role of this breed in the perspective of the ongoing new Common Agricultural Policy (CAP) rules.

Effects of Production Systems and Seasons on Retail-Goat-Milk Fatty-Acid Composition and Nutritional Indices in Greece

Simple Summary

The consumption of goat milk is constantly increasing. However, there are not many studies on the nutritional profile of retail goat milk. This study examined the effects of production systems (conventional and organic) and seasons (spring, summer, autumn and winter) on the fatty acid composition and nutritional indices related to the healthy fat consumption of fluid goat milk sold in the supermarkets. The production system did not significantly affect milk fatty-acid composition nor its nutritional value, whereas seasonal effects were observed. Overall, retail goat milk had a desirable nutritional value, irrespective of production system and season.

Abstract

An increased consumer interest in goat milk has been registered in recent years due to its health-related benefits. This study aimed to investigate the effects of production systems and seasons on fatty-acid composition and nutritional indices for the healthy fat consumption of retail goat milk. The study lasted one year, and milk samples (n = 160) from 14 brands (10 conventional and 4 organic) were collected on a monthly basis. Organic milk had a marginally lower fat and protein content compared with conventionally produced milk according to the declared chemical composition. The production system did not significantly affect milk fatty-acid composition and its nutritional value, indicating that there were no major differences in the feeding strategies between conventionally and organically raised ewes. Seasonal effects were observed in the fatty-acid profile and the nutritional indices. Lower content of saturated fatty acids (SFAs), hypocholesterolemic/hypercholesterolemic ratio (h/H) and linoleic acid/α-linolenic acid (LA/ALA) ratio values were observed in summer. Retail goat milk had a desirable nutritional value, irrespective of production system and season, due to the following characteristics: low atherogenic index (AI) and LA/ALA ratio values, and high h/H ratio, desirable fatty acid (DFA) values and health-promoting index values. In conclusion, neither production nor season significantly impacted the fatty-acid composition and the fat-consumption nutritional indices of retail goat milk produced in Greece.

Candidate Genes and Their Expressions Involved in the Regulation of Milk and Meat Production and Quality in Goats (Capra hircus)

Simple Summary

During the present decade, highly selected caprine farming has increased in popularity due to the hardiness and adaptability inherent to goats. Recent advances in genetics have enabled the improvement in goat selection efficiency. The present review explores how genetic technologies have been applied to the goat-farming sector in the last century. The main candidate genes related to economically relevant traits are reported. The major source of income in goat farming derives from the sale of milk and meat. Consequently, yield and quality must be specially considered. Meat-related traits were evaluated considering three functional groups (weight gain, carcass quality and fat profile). Milk traits were assessed in three additional functional groups (milk production, protein and fat content).

Abstract

Despite their pivotal position as relevant sources for high-quality proteins in particularly hard environmental contexts, the domestic goat has not benefited from the advances made in genomics compared to other livestock species. Genetic analysis based on the study of candidate genes is considered an appropriate approach to elucidate the physiological mechanisms involved in the regulation of the expression of functional traits. This is especially relevant when such functional traits are linked to economic interest. The knowledge of candidate genes, their location on the goat genetic map and the specific phenotypic outcomes that may arise due to the regulation of their expression act as a catalyzer for the efficiency and accuracy of goat-breeding policies, which in turn translates into a greater competitiveness and sustainable profit for goats worldwide. To this aim, this review presents a chronological comprehensive analysis of caprine genetics and genomics through the evaluation of the available literature regarding the main candidate genes involved in meat and milk production and quality in the domestic goat. Additionally, this review aims to serve as a guide for future research, given that the assessment, determination and characterization of the genes associated with desirable phenotypes may provide information that may, in turn, enhance the implementation of goat-breeding programs in future and ensure their sustainability.

Effects of Linseed Supplementation on Milk Production, Composition, Odd- and Branched-Chain Fatty Acids, and on Serum Biochemistry in Cilentana Grazing Goats

The purpose of this study was to investigate the effects of linseed supplementation on milk yield and quality, serum biochemistry and, in particular, to evaluate its possible effects on the production of odd- and branched-chain fatty acids (OBCFA) in the milk of Cilentana grazing goats. Twelve pregnant Cilentana dairy goats were divided into two groups (CTR, control, and LIN, linseed supplementation group). After kidding, the goats had free access to the pasture and both groups received a supplement of 400 g/head of concentrate, but the one administered to the LIN group was characterized by the addition of linseed (in a ratio of 20% as fed) to the ingredients. During the trial, milk samples were taken from April to August in order to evaluate milk production, composition, and fatty acid profile. In addition, blood samples were taken for evaluating the effects of linseed supplementation on goats’ health status. The health status of the goats was not influenced by the linseed supplementation, as confirmed by blood analyses. Concerning the effects on milk, the supplementation positively affected (p < 0.001) milk production and fat percentage and the fatty acid profile was markedly influenced by the lipid supplementation. In particular, milk from the LIN group was characterized by significantly lower concentrations of saturated fatty acids (FA; p < 0.001) and higher proportions of monounsaturated FA, polyunsaturated FA, and conjugated linoleic acids (CLAs) than milk from the CTR group (p < 0.001). In contrast, the OBCFA were negatively influenced by the linseed supplementation (p < 0.0001). Further studies are needed to test the effects of different fat sources and other nutrients on the diets.

Effects of ecotrofin™ on milk yield, milk quality and serum biochemistry in lactating goats

A nutritional supplement (Ecotrofin™, by Vetoquinol Italia S.r.l) recommended in ruminants feeding to strengthen the physiological condition and improve digestive performance was tested in 20 pluriparae grazing goats divided in two groups (control and treated) to assess its possible effects on milk yield and quality and to assess eventual adverse effects. Animals from both groups also received 400 g/day of corn meal, and the treated group was supplemented with 20 g/head/day of the nutritional supplement. At the doses suggested by the manufacturer, despite a transient increase after 30 days of supplementation, Ecotrofin™ did not show significant effects on milk yield and, although some changes were found in the fatty acids profile, no significant improvement of MUFA and PUFA, as well as of omega‐6:omega‐3 ratio and CLA content were seen. Therefore, in our experimental conditions the supplementation of diet with Ecotrofin™ did not appear useful to improve goat's performance. A significant effect on kidney health markers (27 vs. 22.5 for urea and 0.83 vs. 0.76 for creatinine, p < 0.05) suggested a beneficial effect on renal function but, since levels fell in the normal ranges in both groups, such hypothesis would need further studies to be addressed.

Effect of seasonality on physico-chemical and microbiological properties of nicastrese milk and artisanal cheese

Nicastrese is an indigenous Italian goat breed reared in the Calabria region under semi-extensive practices. From January to June, the milk yield of 400 multiparous Nicastrese goats was evaluated. In addition, tank milk and ripened cheese samples were subjected to physico-chemical and microbiological analyses with the aim to assess the effect of the seasonality on quality parameters. The volatile organic compounds profile of the ripened Nicastrese cheese samples was evaluated. Results showed that the seasonality had a significant effect on milk fat, lactose, urea, citric acid contents and acidity. Microbiological analysis of tank milk samples revealed variability among the different microbial groups investigated except for Escherichia coli. In addition, faecal coliforms and Listeria spp. were never detected. Regarding 60 days ripened cheese samples, almost all microbial groups showed a significant decrease during the analysed period, with the exception of Enterobacteria. It is interesting to note that Escherichia coli and Listeria spp. were not detected in any cheese sample investigated, confirming the cheese safety. Overall, volatile organic compounds, detected on cheese samples, decreased trough the investigated period and this behavior could be related to the feeding quality and to the milk's goat nutritional components.

Milk Quality and Animal Welfare as a Possible Marketing Lever for the Economic Development of Rural Areas in Southern Italy

Simple Summary

The growing interest of consumers in products that guarantee animal welfare and a high level of quality should represent the economic lever for small producers in the south of Italy, who mainly manage their farms on pasture or feeding animals with a high forage/concentrate ratio diet. In response to new consumers’ needs, the proposal on the market of these products can be advantageous for small breeders who may require a higher price for the products thus obtained. Our research emphasizes the fact that a greater awareness about the qualities of milk as well as animal welfare positively influence the likelihood of increased consumers’ willingness to pay.

Abstract

The aim of the present work was to investigate the consumers’ willingness to pay (WTP) for dairy products obtained by grazing animals or fed with a high forage/concentrate ratio diet. To this aim, a survey was carried out on Italian consumers in the Campania Region and data collected were analyzed both by simple descriptive statistics and by an econometric model. Our results highlight that young age, knowledge of milk properties, and a healthy lifestyle are extremely important components in determining a higher WTP.

Milk Fatty Acid Profiles in Different Animal Species: Focus on the Potential Effect of Selected PUFAs on Metabolism and Brain Functions

Milk contains several important nutrients that are beneficial for human health. This review considers the nutritional qualities of essential fatty acids (FAs), especially omega-3 (ω-3) and omega-6 (ω-6) polyunsaturated fatty acids (PUFAs) present in milk from ruminant and non-ruminant species. In particular, the impact of milk fatty acids on metabolism is discussed, including its effects on the central nervous system. In addition, we presented data indicating how animal feeding-the main way to modify milk fat composition-may have a potential impact on human health, and how rearing and feeding systems strongly affect milk quality within the same animal species. Finally, we have presented the results of in vivo studies aimed at supporting the beneficial effects of milk FA intake in animal models, and the factors limiting their transferability to humans were discussed.

Milk Production, Body Weight, Body Condition Score, Activity, and Rumination of Organic Dairy Cattle Grazing Two Different Pasture Systems Incorporating Cool- and Warm-Season Forages

Simple Summary

Organic dairy cows were used to evaluate the effect of two pasture production systems on milk, fat, and protein production, somatic cell score, milk urea nitrogen, body weight, body condition score, and activity and rumination. Milk production increased when cows grazed sorghum-sudangrass compared to when they grazed perennial grasses and legumes. Warm-season annual grasses may be incorporated into grazing systems for organic dairy cattle while maintaining milk production and components.

Abstract

Organic dairy cows were used to evaluate the effect of two organic pasture production systems (temperate grass species and warm-season annual grasses and cool-season annuals compared with temperate grasses only) across two grazing seasons (May to October of 2014 and 2015) on milk production, milk components (fat, protein, milk urea nitrogen (MUN), somatic cell score (SCS)), body weight, body condition score (BCS), and activity and rumination (min/day). Cows were assigned to two pasture systems across the grazing season at an organic research dairy in Morris, Minnesota. Pasture System 1 was cool-season perennials (CSP) and Pasture System 2 was a combination of System 1 and warm-season grasses and cool-season annuals. System 1 and System 2 cows had similar milk production (14.7 and 14.8 kg d⁻¹), fat percentage (3.92% vs. 3.80%), protein percentage (3.21% vs. 3.17%), MUN (12.5 and 11.5 mg dL⁻¹), and SCS (4.05 and 4.07), respectively. Cows in System 1 had greater daily rumination (530 min/day) compared to cows in System 2 (470 min/day). In summary, warm-season annual grasses may be incorporated into grazing systems for pastured dairy cattle.

Effect of a high forage : concentrate ratio on milk yield, blood parameters and oxidative status in lactating cows

A feeding strategy that requires a forage:concentrate ratio equal to 70:30, with at least five different herbs in the forage and the use of silages prohibited, has recently been introduced in Italy. Despite the benefits in terms of human health (lower ω6:ω3 ratio, higher conjugated linoleic acid level) of the obtained milk, little information regarding the possible effects on cows’ health is available. The aim of this study was to evaluate the effects of such a feeding strategy in dairy cows (90 days in milk at the beginning of the trial) on milk yield and composition, and blood metabolic profile, including the evaluation of oxidative stress. The proposed feeding strategy, compared with a semi-intensive strategy, resulted in an improvement of animal oxidative status (lower levels of reactive oxygen metabolites, higher levels of antioxidant potential and anti-reactive oxygen metabolites) and a significant increase of milk urea only in the first part of the trial. No differences in milk yield and composition were detected throughout the trial.

Influence of Feeding Linseed on SCD Activity in Grazing Goat Mammary Glands

Simple Summary

The effect of linseed feeding on stearoyl-CoA desaturase (SCD) activity was studied in dairy goats. SCD acts on the synthesis of milk conjugated linoleic acids (CLAs), considered highly important for human health. Linseed feeding significantly changed SCD activity, milk fat, and fatty acid profile; in particular, CLAs were higher in treated animals with potential benefits for human health. Because of the increasing care of consumers for the healthy aspects of foods, results increase the knowledge of beneficial effects of goat milk due to animal nutrition.

Abstract

The effects of linseed feeding on the stearoyl-CoA desaturase (SCD) activity were evaluated on grazing dairy goats divided into two homogeneous groups (C, control, and L, treated) fed the same amount of concentrate which, for group L was supplemented with linseed. Milk yield was unaffected by the treatment. Group L showed significantly higher milk fat (4.10% vs 2.94%, p < 0.01) than group S. Within milk fatty acids, group C showed significantly higher levels of saturated fatty acids and lower values of mono-unsaturated and polyunsaturated fatty acids. In group L, total CLAs were higher than in group S (0.646% vs 0.311%; p < 0.01) mainly because of the differences in CLA cis9 trans 11 (0.623% vs 0.304%; p < 0.01). In treated animals, SCD activity, measured as cis9 C14:1/C14:0, was lower than in the control group, mainly in July and August.

Influence of Pasture on Stearoyl-CoA Desaturase and miRNA 103 Expression in Goat Milk: Preliminary Results

Simple Summary

An experiment to determine the effect of pasture on stearoyl-CoA desaturase (SCD) and micro-RNA (miRNA) 103 expression was carried out on dairy goats. SCD is involved in determining milk content of conjugated linoleic acids (CLAs) that are considered an important health factor in human nutrition. The alterations of the normal pathway of expression of miRNAs can have consequences on the normal cellular physiology and lead to different types of pathologies. The pasture significantly affected milk fat as well as fatty acid profile in goats, in particular CLAs showed higher levels in grazing animals with potential beneficial effects on human health. The pasture affected only the SCD trend, while that of miRNA 103 was influenced only by the stage of lactation. Due to the increasing interest of consumers for the healthy aspects of foods of animal origin, there is an important ongoing debate in the scientific community concerning those factors affecting milk quality in terms of human health. To our knowledge, this is the first observation of the effects of pasture on miRNA expression in milk from ruminant species.

Abstract

The effect of pasture on the stearoyl-CoA desaturase (SCD) and miRNA 103 expression was evaluated on dairy goats divided into two homogeneous groups (G, grazing, and S, stable). Group S was housed in a stall and received alfalfa hay as forage, while group G was led to pasture. The goats of both the groups received the same amount of concentrate. Milk yield did not differ statistically between the groups. Group G showed significantly higher fat (4.10% vs. 2.94%, p < 0.01) and protein percentage (3.43% vs. 3.25%; p < 0.05) than group S. Among milk fatty acids, group S showed significantly higher levels of saturated fatty acids (SFA) and lower values of mono-unsaturated fatty acid (MUFA). The percentages of polyunsaturated fatty acid (PUFA) were not different between groups even if pasture significantly affected the percentages of C18:3 and total omega 3. In group G, total CLAs were twice than in group S (0.646% vs. 0.311%; p < 0.01) mainly due to the differences in CLA cis9 trans 11 (0.623% vs. 0.304%; p < 0.01). Milk total CLA in grazing group was significantly (p < 0.01) higher in August according to the highest value of both linoleic and α-linolenic acids in the pasture. In grazing animals, SCD expression decreased from April to June, increased in July and decreased again in August, while it was almost unvaried along the trial in group S. By contrast, the expression of miRNA 103 showed a similar trend for both groups, decreasing from April to June, increasing in July and falling down in August. To our knowledge, this is the first observation of the effects of pasture on miRNA expression in milk from ruminant species.

Influence of dietary hydrogenated palm oil supplementation on serum biochemistry and progesterone levels in dairy goats

The aim of this research was to investigate the influence of hydrogenated palm oil (HPO) added to a dairy goat diet on serum biochemistry and progesterone levels. Thirty pregnant Cilentana dairy goats were equally divided into 2 groups (control [CTR] and HPO groups). After kidding, concentrated feed for both groups was gradually increased up to 400 g/(animal·d), and the HPO group received 50 g/(animal·d) of HPO. Supplementation with HPO significantly increased cholesterol levels (mg/dL, 63.80 vs. 54.68 at 30 d, P ≤ 0.05; 78.20 vs. 58.00 at 60 d, P ≤ 0.05; 83.80 vs. 57.83 at 120 d, P ≤ 0.01) compared with the CTR group although no significant differences were detected for liver and kidney function indicators. Moreover, other biochemical parameters were not affected by HPO supplementation thus suggesting no change occurred in lipid and protein metabolism. Furthermore, a significant correlation was found between progesterone levels and serum cholesterol (r = 0.65, P ≤ 0.01) although these were not significantly higher in HPO supplemented goats. The dose and time of HPO supplementation appears critical as regards assessing the limits between the risks and benefits of HPO supplementation in dairy goats. At the tested dose, HPO was well tolerated by the animals and may represent a useful tool to increase energy availability during highly demanding periods.

Milk From Cow Fed With High Forage/Concentrate Ratio Diet: Beneficial Effect on Rat Skeletal Muscle Inflammatory State and Oxidative Stress Through Modulation of Mitochondrial Functions and AMPK Activity

Milk and dairy products are relevant components of daily diet and are part of dietary recommendation in many countries due to their content of key nutrients. However, the relatively high content of saturated fat of the milk and its extensive usage for every age group raises concerns about its potential negative health effects. Therefore, in the last years, several researchers dedicated their attention to milk production and quality. Milk fatty acids profile depend on cow feeding and in particular on the type of forage and concentrate and forage/concentrate ratio. It was demonstrated that feeding dairy cows with a 70/30 forage/concentrate ratio yields milk with a low ω6:ω3 ratio and high CLA levels. In this work, we demonstrated that the supplementation of rats diet with this high forage milk (HFM) results, in the skeletal muscle of these animals, in a reduced lipid content and inflammation levels, and an improved mitochondrial lipid oxidation, and redox status through modulation of AMPK activity.

Milk from cows fed a diet with a high forage:concentrate ratio improves inflammatory state, oxidative stress, and mitochondrial function in rats

Excessive energy intake may evoke complex biochemical processes characterized by inflammation, oxidative stress, and impairment of mitochondrial function that represent the main factors underlying noncommunicable diseases. Because cow milk is widely used for human nutrition and in food industry processing, the nutritional quality of milk is of special interest with respect to human health. In our study, we analyzed milk produced by dairy cows fed a diet characterized by a high forage:concentrate ratio (high forage milk, HFM). In view of the low n-6:n-3 ratio and high content of conjugated linoleic acid of HFM, we studied the effects of this milk on lipid metabolism, inflammation, mitochondrial function, and oxidative stress in a rat model. To this end, we supplemented for 4 wk the diet of male Wistar rats with HFM and with an isocaloric amount (82 kJ, 22 mL/d) of milk obtained from cows fed a diet with low forage:concentrate ratio, and analyzed the metabolic parameters of the animals. Our results indicate that HFM may positively affect lipid metabolism, leptin:adiponectin ratio, inflammation, mitochondrial function, and oxidative stress, providing the first evidence of the beneficial effects of HFM on rat metabolism.

Development of a laboratory technique for the evaluation of protease enzymes activity in goat and sheep milk

The shelf life of milk and its products is strongly influenced by the quality of raw milk. Several bacteria present in raw milk can produce proteases: among them, those from psychotropic microorganisms (e.g. Bacillus subtilis), which produce enzymes under refrigeration, cause the most serious problem. The interaction of these enzymes with the milk proteins and the main proteolytic enzymes becomes important in determining the quality of the milk. An artificial substrate (azocasein) was used to quantify the enzyme activity through the release of a chromogenic product that was measured spectrophotometrically after clarifying the sample by the addition of trichloroacetic acid. The detection limit and quantification limit were 1.43 and 4.77mg/ml respectively for sheep milk and, 2.25 and 7.5mg/ml respectively for goat milk. This method is useful for determining the proteolytic activity in different media and its effectiveness depends on chemical-nutritional characteristics of the sample.

Regulation of Stearoyl Coenzyme A Desaturase 1 Gene Promoter in Bovine Mammary Cells

Stearoyl-Coenzyme A desaturase 1 (SCD1) belongs to the fatty acid family of desaturases. In lactating ruminants, the SCD1 protein is highly expressed in the mammary gland and is relevant for the fatty acid composition of milk and dairy products. Bovine mammary epithelial cells (BME-UV1), cultured in vitro, have been proposed as a model to reproduce the biology of the mammary gland. The present study was designed to investigate the responsiveness of bovine SCD1 promoter to serum, insulin, oleic acid, and NFY transcription factor in BME-UV1 cells. A luciferase-based reporter assay was used to monitor the transcriptional activity of the SCD1 promoter region in BME-UV1 cells treated or not with insulin and/or oleic acid. The level of endogenous SCD1 mRNA was evaluated by Real time PCR. Insulin (20 ng/mL) induced a 2.0 to 2.5-fold increase of SCD1 promoter activity. Additionally, the effect of insulin was inhibited by oleic acid, serum components, and NFY enforced expression. Serum and NFY showed no synergistic or additive effect on SCD1 promoter activity suggesting that they repress SCD1 transcription through the same responsive element.