Milk fatty acid composition is a parameter of great interest for evaluation of nutritional quality of milk. Stearoyl-CoA desaturase (SCD) is a key enzyme in mammary lipid metabolism because it is able to add a double bond in the cis delta9-position in a large spectrum of medium- and long-chain fatty acids. A polymorphism with 2 alleles (A and V) in the fifth exon of the SCD gene has been reported. The effect of SCD genotype on individual milk fatty acid composition and on cis-9 unsaturated/saturated fatty acid ratios of 297 Holstein Italian Friesian cows was investigated in this paper. The SCD genotypes were determined by using a single strand conformation polymorphism method. Relative frequencies of SCD genotypes were 27, 60, and 13% for AA, AV, and VV, respectively. Milk of AA cows had a greater content of cis-9 C18:1 and total monounsaturated fatty acids and a higher C14:1/C14 ratio than did milk of VV cows. The relative contribution of SCD genotype to variation of monounsaturated fatty acids, cis-9 C18:1, and cis-9 C14:1 was 5, 4, and 7.7%, respectively. No significant differences were detected between SCD genotypes in the milk content of cis-9, trans-11 C18:2. Results of the present work provide some indication of an association between SCD locus and the fatty acid profile in the examined sample of Italian Holsteins, thus suggesting a possible role of this gene in the genetic variation of milk nutritional properties.

The aim of the study was to evaluate milk fatty acid (FA) profile, animal performance, and rumen microbial population in response to diets containing soybean oil supplemented or not with chestnut and quebracho tannins in dairy ewes. Eighteen Comisana ewes at 122±6 d in milking were allotted into 3 experimental groups. Diets were characterized by chopped grass hay administered ad libitum and by 800 g/head and day of 3 experimental concentrates containing 84.5 g of soybean oil/kg of dry matter (DM) and 52.8 g/kg of DM of bentonite (control diet), chestnut tannin extract (CHT diet), or quebracho tannin extract (QUE diet). The trial lasted 4 wk. Milk yield was recorded daily, and milk composition and blood parameters were analyzed weekly. At the end of the experiment, samples of rumen fluid were collected to analyze pH, volatile fatty acid profile, and the relative proportions of Butyrivibrio fibrisolvens and Butyrivibrio proteoclasticus in the rumen microbial population. Hepatic functionality, milk yield, and gross composition were not affected by tannin extracts, whereas milk FA composition was characterized by significant changes in the concentration of linoleic acid (CHT +2.77% and QUE +9.23%), vaccenic acid (CHT +7.07% and QUE +13.88%), rumenic acid (CHT -1.88% and QUE +24.24%), stearic acid (CHT + 8.71% and QUE -11.45%), and saturated fatty acids (CHT -0.47% and QUE -3.38%). These differences were probably due to the ability of condensed versus hydrolyzable tannins to interfere with rumen microbial metabolism, as indirectly confirmed by changes in the relative proportions of B. fibrisolvens and B. proteoclasticus populations and by changes in the molar proportions of volatile fatty acids. The effect of the CHT diet on the milk FA profile and microbial species considered in this trial was intermediate between that of QUE and the control diet, suggesting a differential effect of condensed and hydrolyzable tannins on rumen microbes. Compared with control animals, the presence of B. fibrisolvens increased about 3 times in ewes fed CHT and about 5 times in animals fed QUE. In contrast, the abundance of B. proteoclasticus decreased about 5- and 15-fold in rumen liquor of ewes fed CHT and QUE diets, respectively. The use of soybean oil and a practical dose of QUE or CHT extract in the diet of dairy ewes can be an efficient strategy to improve the nutritional quality of milk.

Aim of the study was to verify the effects of butyric acid glycerides, as a supplemental ingredient in the diet, on live performance of broiler chickens and on the morphology of their small intestine, since short chain fatty acids are known as selective protection factors against intestinal microbial parasites, potent growth promoters of the gut wall tissues, also in terms of immune modulation response. An experiment was carried out on 150 Ross 308 female chickens, allotted to 5 treatments, over a 35 d ays period: the control, with soybean oil as the energy supplement, and 4 treatments with increasing amounts (0.2, 0.35, 0.5, 1% mixed feed) of a mixture of butyric acid glycerides (mono-, di- and tri- glycerides). Treated animals showed a higher live weight at slaughtering (P<0.05) with a better feed conversion rate. The carcase characteristics were not influenced, but the small intestine wall resulted slightly modified with shorter villi, longer microvilli (P<0.01) and larger crypts depth in jejunum (P<0.01), only with lowest concentration of the supplement (0.2%). It is concluded that butyric acid glycerides are an efficient supplement to broilers’ diets, deserving particular attention as a possible alternative to antimicrobial drugs, which have been banned in Europe