Fatty acid profile and health lipid indices in the raw milk of ewes grazing part-time and hemp seed supplementation of lactating ewes

This experiment was designed to evaluate the effects of the feeding system (indoor  or part-time grazing) of ewes and dietary supplementation with hemp seed (non-drug varieties of Cannabis sativa L.) on milk production and the composition of milk fatty  acids (FAs). The experimental diets were constituted as a 2 x 2 factorial  arrangement of feeding system (I: indoors and receiving 1400 g dry matter (DM)  grass hay/d or pasture grazing (PG)–4 h/day + 700 g DM grass hay/d), and with or without hemp seed (Hs) supplementation (-Hs = no hemp seed vs. +Hs = 175 g/d hemp seed). All animals received 700 g DM/day of a concentrate for lactation.  Feeding the PG diets increased raw milk production and yields of fat, protein and lactose. Feeding +Hs increased fat-corrected milk, milk fat content and fat yield significantly while the combination of +Hs and PG increased fat-corrected milk and fat yield significantly. Milk protein content was not affected by dietary factors. Feeding the I diets increased the proportion of short-chain FAs (C4:0 - C10:0), at the expense of medium-chain FAs (12 to 17 C units). Feeding +Hs decreased the proportion of short-chain FAs, medium-chain FAs and hypercholesterolaemic FA (sum of C12:0, C14:0, C16:0) and increased the trans-vaccenic acid (C18:1 t11, VA), α-linolenic acid (C18:3 n-3, ALA), conjugated linoleic acid (CLA),  eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) concentrations in milk fat significantly. The combination of hemp seed and part-time grazing produced the highest proportion of c9,t11 CLA, t10,c12 CLA and n-3 FA (sum of ALA, EPA, DHA) in milk fat. The polyunsaturated fatty acid (PUFA)/saturated fatty acid (SFA) ratios in the milk from ewes grazing part time were significantly higher, whereas the atherogenicity index (AI), thrombogenic index (TI) and linoleic acid (LA)/ALA ratio were significantly lower compared with the milk of indoor-fed ewes. Supplementing with +Hs has a similar effect of increasing the PUFA/SFA ratio and lowering of the AI, TI and LA/ALA ratio. It was concluded that pasture grazing combined with hemp seed had a synergistic effect on milk production and fat yield without altering the milk protein content in ewes. This combination has favourable effects on milk FA profile from the human consumer’s point of view by increasing the nutritional quality of milk.Keywords: α-linolenic acid, atherogenicitiy index, Cannabis sativa, c9,t11 CLA, n-6/n-3 F

Fatty acid profile and health lipid indices in the raw milk of ewes grazing part-time and hemp seed supplementation of lactating ewes

Abstract This experiment was designed to evaluate the effects of the feeding system (indoor or part-time grazing) of ewes and dietary supplementation with hemp seed (non-drug varieties of Cannabis sativa L.) on milk production and the composition of milk fatty acids (FAs). The experimental diets were constituted as a 2 x 2 factorial arrangement of feeding system (I: indoors and receiving 1400 g dry matter (DM) grass hay/d or pasture grazing (PG)-4 h/day + 700 g DM grass hay/d), and with or without hemp seed (Hs) supplementation (-Hs = no hemp seed vs. +Hs = 175 g/d hemp seed). All animals received 700 g DM/day of a concentrate for lactation. Feeding the PG diets increased raw milk production and yields of fat, protein and lactose. Feeding +Hs increased fat-corrected milk, milk fat content and fat yield significantly while the combination of +Hs and PG increased fat-corrected milk and fat yield significantly. Milk protein content was not affected by dietary factors. Feeding the I diets increased the proportion of short-chain FAs (C4:0 -C10:0), at the expense of medium-chain FAs (12 to 17 C units). Feeding +Hs decreased the proportion of short-chain FAs, medium-chain FAs and hypercholesterolaemic FA (sum of C12:0, C14:0, C16:0) and increased the trans-vaccenic acid (C18:1 t11, VA), α-linolenic acid (C18:3 n-3, ALA), conjugated linoleic acid (CLA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) concentrations in milk fat significantly. The combination of hemp seed and part-time grazing produced the highest proportion of c9,t11 CLA, t10,c12 CLA and n-3 FA (sum of ALA, EPA, DHA) in milk fat. The polyunsaturated fatty acid (PUFA)/saturated fatty acid (SFA) ratios in the milk from ewes grazing part time were significantly higher, whereas the atherogenicity index (AI), thrombogenic index (TI) and linoleic acid (LA)/ALA ratio were significantly lower compared with the milk of indoor-fed ewes. Supplementing with +Hs has a similar effect of increasing the PUFA/SFA ratio and lowering of the AI, TI and LA/ALA ratio. It was concluded that pasture grazing combined with hemp seed had a synergistic effect on milk production and fat yield without altering the milk protein content in ewes. This combination has favourable effects on milk FA profile from the human consumer's point of view by increasing the nutritional quality of milk. _____________________________________________________________________________________

Dietary effect of silage type and combination with camelina seed on milk fatty acid profile and antioxidant capacity of sheep milk

The present study sought to quantify the differences between maize-based (MS) and grass-silage-based (GS) diets in terms of their effect on the milk yield, milk fatty acid composition and antioxidant capacity in dairy ewes, and to test the hypothesis that it is possible to improve yield, fatty acid (FA) composition and antioxidant capacity by supplementing diet with camelina seed (Cs). Experimental diets consisted of a 2 x 2 factorial arrangement of type of silage (GS vs. MS) and camelina seed (−Cs vs. +Cs). Feeding the MS diets increased net energy for lactation (NEL) intake, raw milk yield and fat, protein and lactose yields. Feeding +Cs increased energy corrected milk (ECM), milk fat content and fat yield. Maize silage consumption is associated with an increased proportion of hypercholesterolemic fatty acids (HFA) and a higher value of the atherogenicity index. However, an MS diet led to an increased share of t11-C18:1 and c9,t11-conjugated linoleic acid (CLA) in milk. Milk FA profile in ewes fed GS diet was of higher quality for human beings owing to higher concentrations of α-linolenic acid and a lower content of HFA. Supplementing with camelina seed resulted in a higher concentration of t11-C18:1, c9,t11-CLA and C18:3n-3 in milk fat. The trolox equivalent antioxidant capacity (TEAC) value of milk was higher in milk from MS-fed ewes compared with that of their counterparts fed GS. Dietary supplementation with camelina seed increased the oxidative stability of milk samples. These results suggest that grass-silage-based diet supplemented with camelina seed results in milk of better quality for human consumption.Keywords: Milk quality, oilseed, PUFA profile, oxidative stability of milk, TEAC assa

Effects of breed on milk fatty acid profile in dairy ewes, with particular reference to cis-9, trans-11 conjugated linoleic acid

The objective of this study was to determine and compare the fatty acid profile of milk fat, with particular reference to cis-9, trans-11 conjugated linoleic acid (CLA), in two indigenous Romanian sheep breeds (Spanca and Turcana), irrespective of the effects of diet and season. The ewes (n = 25 for each breed) received the same feed (total mixed rations) and were maintained under identical conditions. Four samples were collected from each individual ewe to determine fatty acids (FA), as methyl esters, using gas chromatography. The fatty acid groups, namely saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) acids were examined together with individual acids. Differences have been obtained between the two local breeds for the majority of FA. Fat in the milk of Turcana ewes has a healthier fatty acid profile than that of Spanca breed which has a lower concentration of SFA (60.9 vs. 73.3%) and higher concentrations of MUFA (31.0 vs. 21.0%) and PUFA (8.06 vs. 5.61%, respectively). Compared with the Spanca breed, fat in the milk of Turcana ewes had higher concentrations of trans-11 C18:1, C18:1 n9c, and cis-9 trans-11 CLA (2.67 vs. 1.01%, respectively). Δ9-desaturase activity is breed specific; vaccenic acid (trans-11 C18:1) desaturation and its conversion into cis-9, trans-11 CLA were more intense in the Turcana breed ewes. In conclusion, breed has a strong effect on the FA composition of ewe milk fat, and on cis-9, trans-11 CLA, in particular. The results obtained, support the sustainable use of animal genetic resources to improve the milk fat quality of ewes.Keywords: CLA, ewe’s milk, fatty acid profiles, Spanca, Turcan

BIOLOGICAL VALUE OF SHEEP MILK BASED ON THE TYPE OF FOOD

In this research study we have analyzed the quality of sheep's milk depending on the food. It has been taken into consideration the milk provided by pasture-fed sheep and hill fertilized lowland pasture, soil podzolic. The breed of sheep is Turcan. There have been studied the chemical characteristics of milk and, and, in order to establish the compared biological value between the two alternatives, milk’fat acids composition has been analyzed. Fat acid’concentration has been performed by means of gas chromatography. There have been determined 19 saturated, monounsaturated and polyunsaturated fat acids. Due to the importance of the essential fat acids, it has been particularily studied their evolution, being obtained the following values Milk provided by sheep fed on unfertilized pasture hill: linoleic acid (ω6); acdlinoleic (ω3) γlinolenic acid (ω6), while the milk provided by sheep fed on lowland pasture: linoleic acid (ω6) -1.85; linolenic acid (ω3) -0.98 γlinolenic acid (ω6) -1.63 and lowland pasture, podzolic soil: acid linoleic (ω6) -2.29; linolenic acid (ω3) -1.19 γlinolenic acid (ω6) -1.25