Influence of Maternal and Postweaning Linseed Dietary Supplementation on Growth Rate, Lipid Profile, and Meat Quality Traits of Light Sarda Lambs

n-6 Polyunsaturated fatty acids in the feeding of late gestation hair ewes: the effects on thermoregulation, growth, and metabolism of heat-stressed growing lambs

The objective was to determine the effects of feeding soybean oil (SBO), an ingredient rich in n-6 polyunsaturated fatty acids (PUFA), to late gestation hair ewes on physiological responses, feedlot performance, and serum metabolite and electrolyte concentrations of their growing ewe lambs under outdoor heat stress conditions. Twenty-four Dorper × Pelibuey ewe lambs weaned (body weight = 21.5 ± 0.2 kg, age= 2 months, and multiple birth) born from ewes fed 0, 30, or 60 mg of SBO/kg dry matter (DM) during late gestation were selected (n = 8/treatment) to conduct a 30-day feeding trial during the summer season of a desert region (temperature = 34 °C and temperature-humidity index = 35 units). While rectal temperature was unaffected in any daytime, respiratory rate in the afternoon quadratically increased (P = 0.05) as the SBO levels increased from 0 to 60 mg/kg DM in the maternal diet. Final weight, average daily gain, and feed efficiency linearly increased (P = 0.04) with increasing levels of SBO. Body surface temperatures and serum concentration of glucose, cholesterol, triglyceride, total protein, urea, sodium, potassium, and chlorine did not vary by the SBO inclusion in the maternal diet. In conclusion, feeding late gestation hair ewes with source rich in n-6 PUFA appears to be an effective maternal nutritional strategy to improve post-weaning growth without compromising the thermoregulatory ability of their growing offspring under a heat stress environment.

Ewe's diet during gestation and lactation affects ready-to-eat meat from light lambs

Maternal grazing may benefit the fatty acid (FA) profile of lamb meat, although any improvement in terms of healthier polyunsaturated FAs (PUFA) may be impaired during subsequent culinary treatments. The objective was to assess the effects of a grass-based ewe diet on the FA profile of the ready-to-eat meat from grain-fed Segureña light lamb. The FA were determined in raw, grilled (G), Sous Vide (SV) cooked and cooked/hot-held (H) lamb leg patties resulting from two maternal rearing systems: grazing (Mediterranean trees, shrubs, herbs, stubble and fallow) or indoors (cereal grain and lucerne pellets). The grass-based ewe diet increased (P < 0.05) levels of n-3 PUFA and total linoleic conjugated acid (CLA), and decreased those of n-6 long chain PUFA and saturated FA (SFA) in the patties from all treatments. These changes in FA slightly increased (P < 0.05) the PUFA/SFA ratio and decreased (P < 0.05) the n-6/n-3 ratio in the raw (from 8.7 to 6.3), SV (from 8.8 to 6.2), G (from 9.0 to 6.3), SV + H (from 8.2 to 6.3) and G + H (from 9.3 to 6.4) patties, improving the atherogenic, thrombogenic and saturation indexes. The effects of the ewe's diet on lamb FA remained unaltered after successive culinary treatments, including aerobically mincing, cooking at an internal temperature of 72 °C and H at 65 °C for 4 h. Heating induced a partial degradation of meat PUFA but also favoured the loss of high saturated melted fat. Both facts balanced the PUFA/SFA ratio in cooked lamb despite the gradual formation of oxidised secondary lipids to the detriment of FA. Grilling or SV cooking did not affect the remaining levels of undegraded FA in the freshly cooked lamb, although SV improved the results obtained for the cooked/H lamb. Maternal diets based on grass result in a healthier ready-to-eat lamb.