Influence of Restricted Grazing Time Systems on Productive Performance and Fatty Acid Composition of <i>Longissimus dorsi</i> in Growing Lambs

Abstract

Fifty 3-month-old male Tan lambs (similar in body weight) were divided into 5 groups to investigate the effects of different restricted pasture grazing times and indoor supplementation on the productive performances and fatty acid composition of the intramuscular fat in growing lambs. The lambs grazed for different periods of time (12 h/d, 8 h/d, 4 h/d, 2 h/d, and 0 h) and received various amounts of supplementary feedings during the 120-day trial. Pasture dry matter intake (DMI), total DMI, average daily gains and the live body weights of the lambs were measured during the experiment. The animals were slaughtered at the end of the study, their carcass traits were measured, and their longissimus dorsi muscles were sampled to analyze the intramuscular fat (IMF) content and fatty acid profiles. The results indicated that the different durations of grazing and supplementary feedings affected the animal performances and the composition of fatty acids. Grazing for 8 h/d or 2 h/d with the corresponding supplementary concentrate resulted in lambs with higher body weights, carcass weights and IMF contents. Lambs with longer grazing times and less concentrate accumulated more healthy fatty acids such as conjugated linoleic acid and n-3 polyunsaturated fatty acid and had higher n-3/n-6 ratios. Overall, a grazing allowance of 8 h/d and the corresponding concentrate was recommended to maintain a high quantity and quality of lamb meat.

Effect of Breed on the Volatile Compound Precursors and Odor Profile Attributes of Lamb Meat

“…Our results echoed Jandasek et al, that IMF content shows a positive correlation with dry matter, and negative correlation with ash content in lambs [ 25 ]. Beyond that, our result showed a great improvement in the IMF of Tan lambs compared to grazing ones in previous study [ 13 ]. It indicated that the Tan lamb had a potential IMF deposition capacity under the indoor-feeding system.…”

“…The designated lamb meat for G20 Summit, Tan lamb, of lower “off-flavor” and “mutton smell”, is famous for its great eating quality and pleasant aroma. Our previous studies found the production performance and meat quality of Tan lamb could be affected by grazing time [ 13 , 14 ]. However, the precursors and odor-active compound profile of Tan lamb are not reported.…”

Effects of concentrate supplementation on fatty acid composition and expression of lipogenic genes of meat and adipose tissues in grazing lambs

“…Guo et al (2014) noted that C/EBPb is induced early to transactivate the expression of C/EBPa and PPARc, two master transcription factors for terminal adipocyte differentiation during 3T3-L1 adipocyte differentiation. The present study also revealed that GS lambs had higher LPL, C/EBPa and PPARc expression levels as well as FAS, ACC and SREBP1c expression levels as mentioned above in SAT or/and LT than NG lambs, indicating more fat deposition in GS than NG lambs as also found by Wang et al (2015), who demonstrated that concentrate supplementation increased IMF content in the LT muscle. At the same time, we found that some genes were influenced by the interaction of feeding regimens and breeds, including ACC, LPL, PPARc and C/EBPa in LT as well as FAS, ACC, LPL and SREBP1c in SAT.…”

Diet selection and n-3 polyunsaturated fatty acid deposition in lambs as affected by restricted time at pasture

“…The diurnal variation in the LNA (α-linolenic acid, C18:3 n-3) content of ryegrass ( Lolium Perenne ) in the sward and the time of day animals were given access to grazing was a factor influencing the FA composition of meat and milk. Meat from lambs restricted to 8-h grazing had increased healthy FAs compared to meat from lambs restricted to 2-h grazing on desert steppe due to their higher pasture intake 5 . To date, very little research has been conducted investigating how restricted grazing regimes alter diet selection (relative intake of individual forage species), and the consequent influence this has on the meat FA profile of lambs when they grazed on natural grasslands with abundant forage species.…”

“…The restriction of grazing time is a way to budget limited pasture, while supplementing to produce high-quality lamb meat. Compared to meat from animals fed concentrates indoors, grazing pasture, even for restricted periods of time each day, improves the FA properties of lamb’s meat 4 , 5 and cow’s milk 6 . The diurnal variation in the LNA (α-linolenic acid, C18:3 n-3) content of ryegrass ( Lolium Perenne ) in the sward and the time of day animals were given access to grazing was a factor influencing the FA composition of meat and milk.…”