Oregano essential oil (OEO), which has antimicrobial properties, may be used for altering the ruminal pH and microbial populations of sheep, as observed by the altered volatile fatty acid patterns. To further elucidate the effects of OEO on ruminal pH and microbial populations of sheep, 3 German merino sheep × local sheep crossbred rams with permanent ruminal fistulas were randomly assigned to a 3 × 3 Latin square design with 12-d periods. The treatments were as follows: control (CON); OEO4: OEO supplied at 4 g•d -1 ; and OEO7: OEO supplied at 7 g•d -1 . Starting on day 11, rumen fluid was collected at 0 h, and at 4, 8, 12, 24 and 48 h after supplying OEO, and then pH values of rumen fluid were immediately measured. The abundance of microbial populations was determined by using qPCR. The ruminal pH values were similar among the sheep from all treatments. The abundance of ruminal fungi was higher for the sheep supplied OEO7 compared with the sheep supplied CON and OEO4, especially at 4 and 12 h. The abundance of ruminal protozoa decreased with supplied OEO, indicating that OEO could inhibit the protozoa. The abundance of the total ruminal bacteria was similar for the sheep from all treatments, but R . flavefaciens , R . albus and F . succinogenes increased in the sheep supplied OEO4 compared with those in the sheep supplied CON, however, the sheep supplied OEO7 had higher abundances of R . flavefaciens than the sheep supplied CON. These results demonstrated that supplying OEO to sheep did not affect the ruminal pH but could shift the rumen microbial population to one with less protozoa. Supplying OEO can preferentially enhance the growth of certain rumen microbial populations, but the shifts were influenced by the supply rate. Therefore, supplying low amount (i.e. 4 g•d -1 ) of OEO could have positive effects on ruminal microbial populations, whereas supplying elevated doses of OEO could be detrimental to those same ruminal microbial populations.
This study assessed breed differences in fatty acid composition and meat quality of Longissimus thoracis et lumborum (LTL) and semitendinosus (SE) of Angus× Chinese Simmental (AS), Wagyu×Chinese Simmental (WS), and Chinese Simmental (CS). CS (n=9), AS (n=9) and WS (n=9) were randomly selected from a herd of 80 bulls which were fed and managed under similar conditions. Fatty acid profile and meat quality parameters were analyzed in duplicate. Significant breed difference was observed in fatty acid and meat quality profiles. AS exhibited significantly (p<0.05) lower C16:0 and higher C18:1n9c compared with CS. AS breed also had a tendency (p<0.10) to lower total saturated fatty acid (SFA), improve C18:3n3 and total unsaturated fatty acid (UFA) compared with CS. Crossbreed of AS and WS had significantly (p<0.05) improved the lightness, redness, and yellowness of muscles, and lowered cooking loss, pressing loss, and shear force compared with CS. These results indicated that fatty acid composition and meat quality generally differed among breeds, although the differences were not always similar in different tissues. Fatty acid composition, meat color, water holding capacity, and tenderness favored AS over CS. Thus, Angus cattle might be used to improve fatty acid and meat quality profiles of CS, and AS might contain better nutritive value, organoleptic properties, and flavor, and could be potentially developed as an ideal commercial crossbreed.
Energy is a key factor regulated by the neuroendocrine system. The objective of this study was to compare growth performance, serum biochemical indices, carcass traits, meat quality, and nutrient composition of lambs fed restricted metabolizable energy (ME) intakes to mimic the seasonal changes of the natural grasslands of northwest China. Nineteen male Dorper × Small Tailed Han lambs were assigned to treatments, control (CON) fed at 1.0 MJ/W 0.75 × d −1 throughout the 180 d study, and restricted ME (RES) fed by sequentially restricting ME every 30 d (0.56, 0.84, 1.0, 0.84, 0.56, and 0.28 MJ/W 0.75 × d −1). Lambs were harvested at the end of the study. Lambs fed the CON diet demonstrated higher (P < 0.05) average daily gain (ADG) compared with RESfed lambs (158.79 and 57.01 g/d, for CON and RES, respectively), although ADG were lower in each period with the last period being a negative ADG for RES-fed lambs resulting in a loss of body weight. Both treatments demonstrated lower ADG in the last 3 study periods compared with the first 2 periods, which may be explained by cold stress (<−3 °C) increasing the lamb's energy requirement. Feeding lambs a restricted ME diet resulted in lower (P < 0.05) blood serum glucose, triglycerides, total protein, calcium, phosphorus, immunoglobulin G, immunoglobulin M, and immunoglobulin A concentrations compared with CON-fed lambs, but both treatments were similar (P > 0.05) for cholesterol and high-density lipoprotein-cholesterol. Feeding lambs a restricted ME diet increased (P < 0.05) meat pH, while reducing the cooked meat rate compared with CON-fed lambs. Thus, the carcass yield, rib eye muscle area, and shear force were lower (P < 0.05) for RES-fed lambs compared with CON-fed lambs. The meat water concentration was higher (P < 0.05), whereas the concentrations of dry matter, crude fat, crude protein, and carbohydrate were lower (P < 0.05) for lambs fed a RES ME diet compared to CONfed lambs. These results demonstrate that sequentially restricting ME intake, as natural grasslands might experience during seasonal forage quality and quantity changes, resulted in a reduction of body weight because lambs were mobilizing body reserves as a source of ME. The reduction in concentrations of key serum nutrients, as well as carcass traits and meat composition, demonstrate the body is responding to the meet the lambs ME requirements, which has implications for both meat quality and the animal's physiological functions.
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