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Biomedical subjects

Z Mir

Publications and source records attributed to Z Mir.

10 recordsLinked to original sources
PubMed2004

Effects of dietary sunflower seeds on rumen protozoa and growth of lambs.

Linoleic acid-rich sunflower-seed supplements (SSS) were used in two experiments (experiment 1, high-concentrate diets; experiment 2, high-forage diets) to study effects on rumen protozoa and the growth of lambs. Both experiments consisted of four treatments, two with a low-protein diet (120 g/kg) and two with a high-protein diet (160 g/kg). For both diets, one treatment was without (control) and one with the SSS (140 g/kg dietary DM). The lambs were fed ad libitum for 70 and 140 d in experiments 1 and 2, respectively. Thereafter, the digestibility of organic matter (OM), acid-detergent fibre and neutral-detergent fibre were determined for each diet with four lambs, and then all lambs were slaughtered and rumen fluid samples were collected and analysed. The results showed substantial decreases (P < 0.001) or total elimination of protozoa in the rumen fluid of the SSS-receiving lambs. In the first experiment the SSS also decreased (P < 0.05) feed intake, but an increase in average daily gain (P < 0.06) resulted in an improved (P < 0.05) feed:gain ratio. Also, the SSS increased (P < 0.05) the digestibility of fibre. In the second experiment the SSS decreased (P < 0.05) the OM digestibility, feed intake and growth of lambs. It was concluded that the use of sunflower-seed supplementation in high-concentrate diets of ruminants reduces rumen fauna, resulting in savings on dietary protein supplements and an increased digestion of feed.

Animals↗
PubMed2004

Effects of biological type and dietary fat treatment on factors associated with tenderness: I. Measurements on beef longissimus muscle.

The objective was to evaluate chemical, mechanical, and sensory attributes associated with tenderness in divergent cattle breeds--Wagyu (W; n = 12), Limousin (L; n = 12) and F1-cross (WxL; n = 12)--fed two dietary treatments (0 or 6% sunflower oil (DM basis)). A randomized complete block repeated measures design in a 3 x 2 factorial arrangement of treatments was used, and effects of breed, diet, block, and associated interactions were tested. Cattle were fed barley-based diets for an average of 259 d. Twenty-four hours postmortem (PM), steaks from the longissimus muscle (LM) were sliced, vacuum-packaged, aged (1, 3, 7, 14, 28, and 56 d PM) at 2 degrees C, and frozen (-40 degrees C) until analyzed. Wagyu steaks had lower (P < 0.05) Warner-Bratzler shear force (WBSF) values than L steaks across all aging times. At 1 d PM, W steaks required slightly more (P > 0.05) force to shear than WxL or L (0.30 and 0.11 kg, respectively); however, by d 14 PM, W steaks required 0.77 kg less (P < 0.05) force to shear than L. Wagyu steaks received higher (P < 0.05) sensory panel sustained tenderness scores at d 14 PM than L. The pH decline was slower (P < 0.05), and temperature decline more (P < 0.05) rapid, in W carcasses than L or WxL carcasses. Breed and diet did not affect (P > 0.10) free calcium levels (FCL) over time (0, 1, 3, 7, and 14 d PM), 0-h calpastatin activity (CA), d-1 percent collagen (OH-PRO), or d-1 collagen cross-linking (HP). Western blot analysis for the presence of the troponin-T (TNT) 30-kDa fragment, conducted only on samples from steers fed the 0% sunflower oil diet, demonstrated more proteolysis by d 3 PM in L than W or WxL. Overall, breed differences in mechanical and sensory measures of tenderness were not explained by FCL, CA, OH-Pro, and HP. Even though the initial appearance of the TNT 30-kDa fragment was greater in L, linear slopes for appearance of TNT degradation product across aging time were greater for W and WxL (P < 0.01 and P = 0.056, respectively) than for L, suggesting that tenderness differences due to breed may have been facilitated by more-rapid proteolytic degradation over time.

Animals↗
PubMed2004

Effects of biological type and dietary fat treatment on factors associated with tenderness: II. Measurements on beef semitendinosus muscle.

The objective of this study was to evaluate attributes in semitendinosus muscle (ST) associated with tenderness in divergent breeds--Wagyu (W; n = 12), Limousin (L; n = 12), and Wagyu x Limousin cross cattle (WxL; n = 12)--fed two dietary treatments (0 or 6% sunflower oil, DM basis). A randomized complete block repeated measures design with a 3 x 2 factorial arrangement of treatments was used to measure effects of breed, diet, block, and associated interactions. Cattle were fed barley-based diets for an average of 259 d. Temperature and pH were measured at 0, 1, 3, 6, 12, and 24 h postmortem (PM). Steaks from the ST were removed 24 h postmortem, vacuum-packaged, aged (1, 3, 7, 14, 28, and 56 d postmortem) at 2 degrees C, and frozen (-40 degrees C) until analyzed. Dietary treatment did not (P > 0.10) affect Warner-Bratzler shear force (WBSF), collagen amount (OH-PRO) or cross-linking (HP), temperature, or pH. Steaks from WxL aged 14 d postmortem had lower (P < 0.05) WBSF values than L (W were intermediate). Cooking time was longer (P < 0.01) in W and WxL than in L; however, breed did not affect (P > 0.10) cooking loss. Cooking time was not influenced by diet, but steaks from cattle fed 6% sunflower oil had lower (P < 0.05) cooking losses. Temperature decreased more (P < 0.05) rapidly, and pH more slowly (P < 0.05), in W and WxL than L in the first 24 h postmortem. Limousin steaks were lighter (higher L*) and more yellow (higher b*) in color than steaks from W and WxL (P < 0.05). The control diet (no oil added) resulted in steaks that were lighter (P < 0.05) than the treatment diet (6% added sunflower oil). Neither breed nor diet affected (P > 0.10) OH-PRO or HP concentration. The results of this study indicate that biological type differences may not be as great in the ST as in longissimus muscle; thus, to increase tenderness in ST, emphasis may need to be placed on processing and cooking techniques rather than genetic selection.

Animals↗
PubMed2004

Value of sunflower seed in finishing diets of feedlot cattle.

The value of sunflower seed (SS) in finishing diets was assessed in two feeding trials. In Exp. 1, 60 yearling steers (479 +/- 45 kg) were fed five diets (n = 12). A basal diet (DM basis) of 84.5% steam-rolled barley, 9% barley silage, and 6.5% supplement was fed as is (control), with all the silage replaced (DM basis) with rolled SS, or with grain:silage mix replaced with 9% whole SS, 14% whole SS, or 14% rolled SS. Liver, diaphragm, and brisket samples were obtained from each carcass. In Exp. 2, 120 yearling steers (354 +/- 25 kg) were fed corn- or barley-based diets containing no SS, high-linoleic acid SS, or high-oleic acid SS (a 2 x 3 factorial arrangement, n = 20). Whole SS was included at 10.8% in the corn-based and 14% in the barley-based diets (DM basis). In Exp. 1, feeding whole SS linearly increased DMI (P = 0.02), ADG (P = 0.01), and G:F (P = 0.01). Regression of ME against level of whole SS indicated that SS contained 4.4 to 5.9 Mcal ME/kg. Substituting whole for rolled SS did not significantly alter DMI, ADG, or G:F (8.55 vs. 8.30 kg/d; 1.36 vs. 1.31 kg; and 0.157 vs. 0.158, respectively). Replacing the silage with rolled SS had no effect on DMI (P = 0.91) but marginally enhanced ADG (P = 0.10) and improved G:F (P = 0.01). Dressing percent increased linearly (P = 0.08) with level of SS in the diet. Feeding SS decreased (P < 0.05) levels of 16:0 and 18:3 in both diaphragm and subcutaneous fats, and increased (P = 0.05) the prevalence of 18:1, 18:2, cis-9,trans-11-CLA and trans-10,cis-12-CLA in subcutaneous fat. In Exp. 2, barley diets supplemented with high-linoleic SS decreased DMI (P = 0.02) and ADG (P = 0.007) by steers throughout the trial, whereas no decrease was noted with corn (interaction P = 0.06 for DMI and P = 0.01 for ADG). With barley, high-linoleic SS decreased final live weight (554 vs. 592 kg; P = 0.01), carcass weight (329 vs. 346 kg; P = 0.06), and dressing percent (58.5 vs. 59.4%; P = 0.04). Steers fed high-linoleic SS plus barley had less (P < 0.05) backfat than those fed other SS diets. No adverse effects of SS on liver abscess incidence or meat quality were detected. Although they provide protein and fiber useful in formulating finishing diets for cattle, and did improve performance in Exp. 1, no benefit from substituting SS for grain and roughage was detected in Exp. 2. Because of unexplained inconsistencies between the two experiments, additional research is warranted to confirm the feeding value of SS in diets for feedlot cattle.

Adipose Tissue↗
PubMed2002

Growth, carcass characteristics, muscle conjugated linoleic acid (CLA) content, and response to intravenous glucose challenge in high percentage Wagyu, Wagyu x Limousin, and Limousin steers fed sunflower oil-containing diet.

The effect of breed and diet on insulin response to glucose challenge and its relation to intramuscular fat deposition was determined in 36 steers with 12 each of greater than 87% Wagyu (referred to as Wagyu), Wagyu x Limousin, and Limousin breeds. Weaned steers were blocked by weight into heavy, medium, and light calves and placed in six pens with two pens per weight type and with two steers of each breed per pen. Three pens with steers from each weightclass were fed backgrounding and finishing diets for 259 d, while the other three pens were fed the same diets where 6% of the barley grain was replaced with sunflower oil. Prior to initiation of the finishing phase of the study the intravenous glucose tolerance test (VGTIT) was conducted in all steers. Once steers were judged as carrying adequate 12th-rib fat, based on weight and days on feed, they were harvested and graded and samples of the longissimus muscle were procured for determination of fat content and fatty acid composition. Dietary oil improved (P = 0.011; 0.06) ADG and feed conversion efficiency of steers during the latter part of backgrounding and only ADG during early part ofthe finishing period. Generally percent kidney, pelvic, and heart fat was the only adiposity assessment increased (P = 0.003) by dietary oil. The IVGTT results indicated that insulin response to intravenous glucose was lower in Limousin steers than in Wagyu steers. Dietary oil decreased (P = 0.052) fasting plasma insulin concentration in Wagyu steers compared with Limousin steers. The correlation coefficients among the IVGTT measures and intramuscular fat content or marbling score were less than 0.4, and only a negative trend existed between fasting insulin and USDA marbling scores. However, the carcasses of the Wagyu steers graded US Choice, and 66% of the Wagyu carcasses graded US Prime, which were substantially better than the quality grades obtained for the carcasses from the other breed types. Dietary oil did not affect muscle fat content but increased (P = 0.01) conjugated linoleic acid (CLA) concentrations by 339%. Results indicated that IVGTT measures were not appropriate indices of marbling potential in cattle and that dietary oil can enhance CLA content of beef.

Adipose Tissue↗
PubMed1998

A review of bloat in feedlot cattle.

Improvements in feedlot management practices and the use of various feed additives have reduced, but not eliminated, the occurrence of bloat in feedlot cattle. Feedlot bloat reduces the profitability of production by compromising animal performance and more directly by causing fatalities. In feedlots, bloat is associated with the ingestion of large amounts of rapidly fermented cereal grain and destabilization of the microbial populations of the rumen. An abundance of rapidly fermented carbohydrate allows acid-tolerant bacteria (e.g., Streptococcus bovis and Lactobacillus spp.) to proliferate and produce excessive quantities of fermentation acids. As a result, ruminal pH becomes exceedingly low, and this impairs rumen motility. Further, the excessive production of mucopolysaccharide or "slime" increases the viscosity of ruminal fluid and stabilizes the foam implicated in frothy feedlot bloat. Although protocols have been developed to treat feedlot bloat, the most profitable approach is to use management strategies to reduce its likelihood. Amount of roughage, grain processing techniques, selection of cereal grain (e.g., corn, barley, and wheat), dietary adaptation periods, and various additives (e.g., ionophores) can influence the occurrence of bloat in feedlot cattle. Successful management of these factors depends on a thorough understanding of the behavioral, dietary, and microbial events that precipitate bloat in feedlot cattle.

Animal Husbandry↗
PubMed1994

Effect of the addition of live yeast (Saccharomyces cerevisiae) on growth and carcass quality of steers fed high-forage or high-grain diets and on feed digestibility and in situ degradability.

The effects of adding yeast culture (Saccharomyces cerevisiae, 5 x 10(9) live organisms/g of growth medium) at 10 g/steer daily to three diets consisting of 75% alfalfa silage and 25% barley, 96% corn silage and 4.0% soybean meal, or 75% dry-rolled barley and 25% alfalfa hay on performance of growing and finishing steers and carcass characteristics, feed digestibility, and degradability in the rumen were determined. In separate trials over 2 yr, the performance of steers fed the three diets with no supplementary live yeast (control; C) or with live yeast (Y) was determined using 72 Hereford steer calves in eight pens each year in a randomized complete block design. The diets were fed sequentially and the steers were randomized before diets were switched. Each year at the end of the high-grain feeding segment of the trial, the steers were slaughtered when ultrasound backfat was such that the carcass would grade A1 or A2 (Canadian grades). The digestibility of feed DM, CP, and NDF of the three diets was determined sequentially using six and eight mature, ruminally cannulated steers in 2 yr, respectively. The degradation characteristics of the three diets in the rumen were determined using the nylon bag technique in two steers for each additive treatment. In the 1st yr, the feed efficiency of the corn silage diet was lower (P < .05) for C than for Y steers (5.9 vs 6.8). Differences (P < .05) were not observed between C and Y steers for any of the performance or carcass characteristics.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1977

Average multichannel EEG potential fields evoked from upper and lower hemi-retina: latency differences.

Checkerboard reversals shown to the upper hemiretina evoke EEG potentials which in anterior-posterior derivations are approximately inverted in polarity compared with potentials evoked by lower hemiretinal stimulation. Using a 48-channel system, EEG scalp field distributions of such responses were mapped. Examination of the map sequences shows that occipital positive maximal field values start to develop at about the same time in the two stimulus conditions, but peak much earlier and somewhat more anteriorly for upper than for lower hemiretinal stimulation. Thus, there is a difference of response latency in the two conditions, which accounts for the approximate inversion of polarity. Possible correlations with reports of higher receptor cell density, higher visual acuity, and shorter motor reaction time of the upper hemiretinal system are noted.

Adult↗
PubMed1976

[Methods and evaluation of visually evoked EEG potentials in cases of suspected multiple sclerosis (author's transl)].

In multiple sclerosis, average EEG potentials which are monocularly evoked by checkerboard pattern reversal frequently show increased latencies of the dominant, occipitally positive peak (more than 110 ms), and latency differences of more than 6--7 ms between responses to right and left eye stimulation. Fixation of the stimulus field at the lower border causes significantly longer latencies and smaller amplitudes than fixation at the upper border. With lower border fixation, the increase of response latency may suggest a reversal of response polarity in extreme cases. Central fixation often but not always results in responses similar to upper border fixation. In order to have minimal variability of the results, fixation of the stimulus field at the upper border is preferred over central fixation.

Electroencephalography↗