The reduction of starch in finishing diets supplemented with oil does not prevent the accumulation of trans-10 18:1 in lamb meat1

Abstract

The experiment was conducted to test the hypothesis that the replacement of cereal with low-starch feed ingredients in lambs' finishing diets supplemented with oils could prevent the accumulation of -10-18:1 in meat. Forty lambs were fed 1 of 4 diets supplemented with soybean oil (5.9%) and fish oil (1%) for 6 wk before slaughter. The control (CON) diet contained 43% barley, and in the other diets, barley was completely replaced by dehydrated citrus pulp (DCP), dehydrated sugar beet pulp (DBP), or soybean hulls (SH). Growth performance, feed intake, and carcass and meat quality traits were analyzed. At slaughter, LM samples were collected for gene expression evaluation, and 3 d after slaughter, LM and subcutaneous (s.c.) fat samples were collected for fatty acid analysis. None of the diets affected meat quality, but the DCP diet reduced ADG ( < 0.05) and the DCP and SH diets decreased the feed-to-gain ratio ( < 0.01). The DCP diet increased ( < 0.05) the risk of parakeratosis and the severity of the lesions. Moreover, the DBP treatment led to increased a* (redness) and b* (yellowness) in s.c. fat compared with the CON treatment ( < 0.05). The lipid content of LM did not differ ( > 0.05) with treatment and averaged 34.4 g/kg of meat. Diets had no effect ( > 0.05) on SFA, PUFA, and -MUFA sums and on the -6:-3 ratio in both LM and s.c. fat. A lower expression of fatty acid synthase (FASN) was found with the DCP treatment than with the other treatments ( < 0.001). All treatments showed a high accumulation of -10-18:1, averaging 91 mg/g fatty acid in LM and 147 mg/g fatty acid in s.c. fat. The concentration of -11-18:1 in the tissues was considerably lower than that of -10-18:1, and thus the -10-18:1:-11-18:1 ratio was above 3 with all treatments. Despite this, the SH diet clearly promoted a larger deposition of -11-18:1 and -9,-11-18:2 in tissues compared with the other treatments. () gene expression and SCD activity index in LM were reduced with the SH diet compared with the CON and DCP diets. Overall, these results clearly showed, for the first time, that low-starch/high-NDF diets are not able to prevent the establishment of -10 shifted rumen biohydrogenation pathways, evaluated by the deposition of biohydrogenation intermediates in lamb meat and fat.

Intramuscular Fatty Acids in Meat Could Predict Enteric Methane Production by Fattening Lambs

“…Such a low value was derived from the high trans-11 C18:1 content in the SH treatment, which was three-fold higher than the average trans-11 C18:1 level in other treatments of that study (Table 5). Nevertheless, the results of the comparison supported the relationship between calculated CH 4 production and intramuscular FA profile and encouraged us to develop a new and more generalizable regression equation including both our own data and those from Costa et al [41], Oliveira et al [42] and Santos-Silva et al [43] (Tables 2-5). In this new statistical model (Equation (4)), calculated CH 4 production with Equation (4) of Sauvant et al [28] was the variable, C17:0 iso, C17:0 anteiso, cis-11 18:1, trans-11 18:1 and average BW were the predictors, and the regression was weighted by the squared root of the number of observations in each experimental treatment.…”

“…Unfortunately, published papers on CH 4 emissions of lambs that simultaneously report a detailed meat FA profile are scant. Therefore, in order to challenge our approach, we constructed a database with diet composition, average DMI and BW, and intramuscular FA profile of lambs from previous published works [41][42][43]. Then, we derived the OMD at maintenance levels in their diets from tabulated data of feed composition [44] and calculated CH 4 production in two ways: (i) using Equation (4) of Sauvant et al [28] (Table 4) and (ii) using intramuscular FA contents in Equation ( 3) of the present study, scaled to BW to include BW effects on DMI (Table 5).…”

“…Equation ( 3) was chosen over Equation (2) because one publication did not report C14:0 iso contents in intramuscular fat [42]. It is important to note that [41][42][43] included about 6% of highly unsaturated oils in their studies, which is known to have a great impact on the intramuscular FA profile due to its effects on ruminal fermentation [45,46]. Table 4.…”

“…Apparent organic matter digestibility (OMD, %) and digestible organic matter (DOM, % dry matter) of the diets at maintenance feeding level, body weight (BW, kg), dry matter intake (DMI, kg/d), actual feeding level (g dry matter intake/kg body weight), and calculated methane (CH 4 ) production (g/d) of lambs allocated to several experimental treatments in the studies of Costa et al [41], Oliveira et al [42] and Santos-Silva et al [43]. It was found that calculated CH 4 with Equation (4) of Sauvant et al [28] (Table 4) and Equation ( 3) of the present study (Table 5) were correlated (r = 0.52), although statistical significance was not reached (p = 0.10) due to the low calculated value of CH 4 production with Equation (3) in the SH diet of Costa et al [41]. Such a low value was derived from the high trans-11 C18:1 content in the SH treatment, which was three-fold higher than the average trans-11 C18:1 level in other treatments of that study (Table 5).…”

Feeding Algae Meal to Feedlot Lambs with Competent Reticular Groove Reflex Increases Omega-3 Fatty Acids in Meat

“…The contents of some minor cis MUFA showed differences between treatments, but total cis MUFA and the quantitatively main cis isomer, cis-9 18:1, were not affected by algae meal supplementation (Table 3). Regarding trans 18:1 FA, trans-10 was the major isomer in all meats as usually found in the IMF of lambs that are fed concentrate based diets, even those with a low starch proportion [24,29,30]. Interestingly, trans-10 18:1 content was lower in the NOALG and ALGMILK treatments than in the ALGCON treatment, which would suggest both, that the PUFA of algae meal boosted the trans-10 shifted rumen BH pathway in the ALGCON treatment [31] and that the RGR was effective in by-passing the rumen [16].…”