Effect of salinomycin supplementation on characteristics of digestion and feedlot performance of cattle

One hundred fifty large-frame British-cross calves, 75 heifers and 75 steers averaging 220 kg, were used in a 187-d growing-finishing trial to study the influence of dietary salinomycin levels of 0, 5.5, 11, 16.5 and 22 mg/kg on rate and efficiency of gain. The basal diet to which the ionophore was added was composed largely to steam processed grains, and contained 3% supplemental fat. Performance responses to salinomycin supplementation were similar for steers and heifers. Rate of gain was not influenced (P greater than .20); however, feed conversion was improved by an average of 5% at the 11- to 22-mg/kg levels of salinomycin supplementation (P less than .05). Although not necessarily mutually exclusive, this improvement in feed conversion could be accounted for as either a 5% increase in the net energy value of the diet (P less than .05) or a 10% reduction in maintenance requirement (P less than .10). Four steer calves (234 kg) with cannulae in the rumen and proximal duodenum were used in a 4 X 4 Latin-square design trial to determine the influence of salinomycin supplementation on characteristics of digestion. Four levels of supplementation (0, 55, 11 and 16.5 mg/kg) were evaluated using the same basal diet as in the performance trial. Total tract digestion of organic matter, acid detergent fiber, starch and protein was not significantly altered by salinomycin supplementation. However, ruminal digestion of organic matter was reduced 6.2% (P less than .05). Neither ruminal degradation of feed protein nor net microbial synthesis was significantly altered.(ABSTRACT TRUNCATED AT 250 WORDS)     

Relationship of fatty acid composition to intramuscular fat content in beef from crossbred Wagyu cattle.

The deposition of i.m. fat, or marbling, in cattle is recognized as a desirable carcass trait in North American beef grading schemes. In order to investigate the relationship between degree of marbling and fatty acid composition of whole bovine muscle, we extracted the total lipid from pars costalis diaphragmatis (PCD) (n = 23) and longissimus (n = 36) muscles from Wagyu crossbred cattle that were assigned Canadian Grading Agency marbling scores ranging from 1 to 8 on an inverse 10-point scale (i.e., a score of 1 indicated "very abundant" marbling and a score of 10 would be assigned to a carcass "devoid" of marbling). Fatty acid methyl esters (FAME) of the total lipid and triacylglycerol fractions were resolved and quantified through GLC. Marbling scores were negatively associated with total lipid from both PCD (r = -.57, P < .01) and longissimus (r = -.80, P < .001). Differences between PCD and longissimus were found for almost all FAME studied from both lipid fractions, but no differences (P > .05) were seen when the monounsaturated:saturated fatty acid (MUFA/SFA) ratios were compared. Heifers had higher (P < .05) oleic acid content and lower (P < .05) palmitic acid content in lipid extracted from both muscles, resulting in higher (P < .05) MUFA/SFA ratios than those for steers. The relative amount of myristic acid increased as the lipid content (total lipid and triacylglycerol) increased in either longissimus (r values from .48 to .55; n = 36; P < .01) or PCD muscles (r from .67 to .76; n = 23; P < .001). The relative amount of linoleic acid (cis-9, cis-12 isomer) from total lipid was negatively associated with all chemical measurements of lipid from the longissimus (r from -.52 to -.64; n = 36; P < .001) and PCD muscles (r from -.75 to -.85; n = 23; P < .001). This association was not significant (P > .1) for either muscle when linoleic acid from the triacylglycerol fraction was examined, suggesting the negative association between this fatty acid and lipid content was due to a dilution of membrane phospholipids with increasing triacylglycerol. Indices of fatty acid elongase activity, calculated from FAME data, implicated the balance between this enzyme activity and fatty acid synthase as a source of variation between animals displaying various degrees of marbling and worthy of further investigation to better understand the process of marbling fat deposition in beef cattle.     

Repeatability of ultrasound-predicted percentage of intramuscular fat in feedlot cattle.

We used data from 144 bulls, heifers, and steers to determine the repeatability of ultrasound-predicted percentage of intramuscular fat and to study the effect of repeated measurements on the standard error of prediction. Animals were scanned at an average age of 433 d by a certified technician. Individual bulls, heifers, and steers were scanned five to six times each with two Aloka 500-V machines, and the percentage of intramuscular fat was predicted from two regions of interest within an image. Variance components and repeatability values were computed for the overall data and by machine, region of interest, and sex. Animals were broadly divided into two groups based on mean ultrasound-predicted percentage of intramuscular fat. Variance components and repeatability values were then estimated within each group. The overall repeatability of ultrasound-predicted percentage of intramuscular fat was .63 +/- .03. Differences in the repeatability values between machines and between regions of interest were not different from zero (P > .05). Bulls showed a lower within-animal SD of .82% as compared to .97 and 1.02% for steers and heifers, respectively. However, steer ultrasound-predicted percentage of intramuscular fat measures were more repeatable (P < .05) than those of bulls and heifers. The difference in repeatability between bull and heifer measures was not important (P > .05). Animals with mean ultrasound-predicted percentage of intramuscular fat less than 4.79% showed less repeatable measures (P < .05) than those with means above 4.79%. The image variance contributed to nearly 70% of the total variance of observations within an animal. Standard error of animal mean measures showed a 50% reduction when the number of images per animal increased to four. Therefore, we concluded that increasing the number of images per animal plays a more significant role in reducing the standard error of prediction than taking multiple measurements within a single image.     

Relationship between the expression of key lipogenic enzymes,fatty acid composition,and intramuscular fat content of Limousin and Aberdeen Angus cattle

The amount and fatty acid composition of intramuscular fat (IMF) are major factors in determining the nutritional value of beef. Understanding the mechanisms regulating IMF formation is important for designing strategies for manipulation of IMF quantity and quality. The aim of this study was to investigate the contribution of key lipogenic enzymes towards intramuscular fat formation in Aberdeen Angus and Limousin crossbred steers. This study reports the presence of 150 kDa acetyl-CoA-carboxylase α (ACCα), 150 kDa fatty acid synthase (FAS), 37 kDa stearoyl-CoA desaturase (SCD), 50 kDa Δ6-desaturase (Δ6d), and 50 kDa Δ5-desaturase (Δ5d) immunoreactive bands in cattle muscle (as detected by Western blot analyses). A significant positive relationship was established between ACCα protein content and IMF content; FAS protein content and IMF, as well as between expression of these enzymes and the products of their reactions, saturated fatty acid. IMF level was also positively related to the expression of Δ6d and Δ5d proteins. However, no relationship was found between IMF and the amount of SCD protein. It is suggested that the rate of saturated fatty acids and PUFA biosynthesis might have a significant impact on IMF deposition in cattle.     

Longitudinal analysis of body weight and average daily feed intake during the feedlot test period in Angus cattle

The objectives of this study were to compare different models for analysing body weight (BW) and average daily feed intake (ADFI) data collected during a 70-day feedlot test period and to explore whether genetic parameters change over time to evaluate the implications of selection response. (Co)variance components were estimated using repeatability and random regression models in 2,071 Angus steers. Models included fixed effects of contemporary group, defined as herd–year–observation_date–age, with additive genetic and permanent environmental components as random effects. Models were assessed based on the log likelihood, Akaike's information criterion and the Bayesian information criterion. For both traits, random regression models (RRMs) presented a better fit, indicating that genetic parameters change over the test period. Using a two-trait RRM, the heritability from day 1 up to day 70 for BW increased from 0.40 to 0.50, while for ADFI, it decreased from 0.44 to 0.33. The genetic correlation increased from 0.53 at day 1 up to 0.79 at day 70. Selection based on an index assuming no change in genetic parameters would yield a 2.78%–3.13% lower selection response compared to an index using parameters estimated with RRMs and assuming these genetic parameters are correct. Results imply that it may be beneficial to implement RRMs to account for the change of parameters across the feedlot period in feed efficiency traits.     

Genetic antagonism between body weight and milk production in beef cattle

Korean cattle have an unusually short suckling period (4 mo) due to poor milking ability, and this is a hindrance to growth of calves. Therefore, Korean cattle breeders have shown interest in genetic improvement of milking ability. In this study, body weight (birth weight, weaning weight, and yearling weight) and five daily milk yields by period in Korean cattle (Hanwoo) were analyzed using a two-trait sire and maternal grandsire mixed model. The milk yields used were actually measured at sequential intervals from 1 to 4 mo after calving. Posterior means of the parameters were estimated using Gibbs sampling. Heritability estimates (0.25 to 0.26) for daily milk yield at weaning were larger than those with other periods. Genetic impact on daily milk yield, especially at weaning, was emphasized in order to lengthen the suckling period of Korean cattle. Genetic correlation estimates between BW and daily milk yield were all negative (-0.08 to -0.16 for birth weight, -0.04 to -0.21 for weaning weight, and -0.12 to -0.19 for yearling weight), whereas environmental correlation estimates were all positive (0.20 to 0.39 for birth weight, 0.34 to 0.51 for weaning weight, and 0.30 to 0.45 for yearling weight). The negative estimates of genetic correlation between weight and milk yield implied genetic antagonism between direct and maternal effects for weaning weight of beef cattle.     

Impact of corn vitreousness and processing on site and extent of digestion by feedlot cattle

Eight cannulated Holstein steers (average BW: 251 kg) were used in 2 simultaneous 4 x 4 Latin squares in a split-plot arrangement to test the effects of processing method [dry-rolled (DR) vs. steam-flaked (SF); main plot] and vitreousness (V, %; subplot) of yellow dent corn (V55, V61, V63, and V65) on site of digestion of diets containing 73.2% corn grain. No vitreousness x processing method interactions were detected for ruminal digestion, but ruminal starch digestion was 14.4% lower (P < 0.01) for DR than for SF corn. Interactions were detected between vitreousness and processing method for postruminal (P < 0.10) and total tract digestion (P < 0.05). With DR, vitreousness tended to decrease (linear effect, P < 0.10) postruminal OM and starch digestion. With SF, vitreousness did not affect (P > or = 0.15) postruminal digestion of OM and starch. Postruminal N digestion tended to decrease (linear effect, P = 0.12) as vitreousness increased. Postruminal digestion was greater for SF than for DR corn OM (25.7%, P < 0.05), starch (94.3%, P < 0.10), and N (10.7%, P < 0.01). Steam flaking increased total tract digestion of OM (11%, P < 0.05), starch (16%, P < 0.01), and N (8.4%, P < 0.05) but decreased total tract ADF digestion (26.7%, P < 0.01). With DR, total tract starch digestion was lower for V65 (cubic effect, P < 0.10) than for the other hybrids. With SF, total tract starch digestion was not affected (P > or = 0.15) by vitreousness. Fecal starch and total tract starch digestion were inversely related (starch digestion, % = 101 - 0.65 x fecal starch, %; r2 = 0.94, P < 0.01). Ruminal pH was greater for steers fed DR than for steers fed SF corn (6.03 vs. 5.62, P < 0.05). Steam flaking decreased (P < 0.01) the ruminal molar proportion of acetate (24%), acetate:propionate molar ratio (55%), estimated methane production (37.5%), and butyrate (11.3%, P < 0.05). There was a vitreousness x processing interaction (P < 0.01) for acetate:propionate. For DR, acetate:propionate tended to increase (linear effect; P < 0.10) with increasing vitreousness. With SF, acetate:propionate was greater (cubic effect, P < 0.01) for V65. Starch from more vitreous corn grain was less digested when corn grain was DR, but this adverse effect of vitreousness on digestion was negated when the corn grain was SF. Of the 19% advantage in energetic efficiency associated with flaked over rolled corn grain, about 3/4 can be attributed to increased OM digestibility, with the remaining 1/4 ascribed to reduced methane loss.     

Influence of forage level on response of feedlot steers to salinomycin supplementation

Two trials were conducted to evaluate the influence of forage level on the response of feedlot cattle to salinomycin. Diets containing 10, 15 and 20% forage were compared with 0 or 11 mg/kg salinomycin. In trial 1, treatment effects on feedlot performance were evaluated using 108 crossbred steers (295 kg) in a crossover design experiment. There were no salinomycin X forage level interactions (P greater than .20). Weight gain response to salinomycin supplementation averaged 5.4, 5.3 and 6.9%, respectively, for diets containing 10, 15 and 20% forage. Corresponding values for feed conversion response to salinomycin supplementation were 5.1, 3.9 and 5.9%. Averaged across forage level, salinomycin supplementation improved rate of weight gain and feed conversion by 5.9 and 5.2%, respectively (P less than .01). In trial 2, treatment effects on characteristics of ruminal and total tract digestion were evaluated in a 6 X 6 Latin-square design trial involving six crossbred steers (191 kg) with cannulae in the rumen and proximal duodenum. There were no interactions between salinomycin supplementation and forage level on characteristics of ruminal digestion (P greater than .20). Salinomycin supplementation did not influence synthesis of microbial N, ruminal digestion of organic matter, acid detergent fiber and starch, or molar proportions of acetate, propionate and butyrate (P greater than .20). Salinomycin supplementation increased passage of non-ammonia N to the small intestine (5.4%, P less than .10) and increased ruminal escape of feed N (24%, P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)     

绿雁土鸡体重、体尺的相关性研究

运用SPSS软件对180羽绿雁土鸡进行体重、体尺相关分析、通径分析,建立最优回归方程。结果表明：绿雁土鸡公鸡体重与体斜长、胸深、胸宽、胫长、胫围呈极显著正相关（P〈0.01）;母鸡体重与体斜长、龙骨长、胸宽、胫围呈极显著正相关（P〈0.01）。经通径分析,公鸡体尺与体重的相关性依次为胸宽、胫长、体斜长、胸围、胸深、龙骨长、骨盆宽;母鸡依次为体斜长、龙骨长、胫围、胸宽、胫长、骨盆宽、胸深。     

Influence of free fatty acid content on the feeding value of yellow grease in finishing diets for feedlot cattle.

Holstein steers (n = 96; 375 kg) were used in a 144-d growth-performance trial to evaluate influence of level (42, 28.5, and 15%) of FFA content on feeding value of yellow grease. Two sources of yellow grease were compared: conventional yellow grease (CYG), containing 15% FFA, and griddle grease (GG), containing 42% FFA. Dietary treatments consisted of an 88% concentrate finishing diet supplemented with either 1) 0% fat, 2) 5% GG, 3) 2.5% GG and 2.5% CYG, or 4) 5% CYG. Fat supplementation increased ADG (11%; P<.05), feed efficiency (9%; P<.05), diet NE (6.4%; P<.05), carcass weight (4%; P<.10), dressing percentage (1%; P<.10), and kidney, pelvic, and heart fat (20%, P<.05). Increasing the FFA in supplemental fat increased (linear effect, P<.10) DM intake, ADG, and feed efficiency and decreased (linear effect, P<.10) retail yield. These improvements in performance were primarily due to increased DM intake. The NEm and NEg values of supplemental fats were not affected by FFA content, averaging 4.98 and 3.85 Mcal/kg, respectively. Treatment effects on characteristics of ruminal and total tract digestion were evaluated using four Holstein steers (180 kg) with cannulas in the rumen and proximal duodenum. Supplemental fat did not influence (P>.10) ruminal or total tract digestion of OM, ADF, starch or N. Postruminal fatty acid digestion was less (P<.10) for fat-supplemented diets than for unsupplemented diets (73.0 vs. 78.6%). The decrease in postruminal fatty acid digestibility with fat supplementation was mainly due to a decreased (16.7%; P<.05) digestibility of C18:0. Postruminal digestibility of the supplemental fat was 68%. There were no treatment effects (P>.10) on ruminal pH. Ruminal biohydrogenation of fatty acids was directly proportional to estimates of methane production. We conclude that the feeding value of conventional yellow grease and griddle grease is similar and that differences in the FFA content of yellow grease will not negatively affect diet acceptability and growth performance of feedlot cattle.     

Influence of level and source of dietary fat on its comparative feeding value in finishing diets for steers: feedlot cattle growth and performance

Two hundred twenty-eight crossbred steers (304 kg) were used in a 125-d comparative slaughter trial to evaluate the influence of level and source of supplemental fats on their feeding value for feedlot cattle. Dietary treatments consisted of a steam-rolled, barley-based finishing diet containing 1) no supplemental fat; 2) 4% yellow grease (YG); 3) 4% blended animal-vegetable fat (BVF); 4) 8% YG; 5) 8% BVF or 6) 6% BVF and 2% crude soybean lecithin. Increasing level of supplemental fat in the diet resulted in linear improvements (P less than .01) in weight gain, feed conversion and NE value of the diet. Estimated NE values of YG and BVF were similar and did not appear to be influenced by level of supplementation, averaging 5.78 and 4.61 Mcal/kg for maintenance and gain, respectively. Fat supplementation resulted in linear increases in empty body fat (P less than .01), kidney, pelvic and heart fat (P less than .01) and marbling score (P less than .05). Partially replacing BVF with lecithin did not influence (P greater than .10) steer performance, carcass merit or estimated NE value of the diet. The comparative feeding value (in terms of both diet acceptability and NE value) of the supplemental fats tested was similar and was apparently not influenced by level of supplementation up to 8% of diet DM.     

文山高峰牛母牛体重与体尺的相关性分析

[目的]为了探究文山高峰牛母牛的体重与体尺性状的相关性,建立文山高峰牛母牛体重与体尺性状之间的最优回归方程,为文山高峰牛遗传参数的选择提供参考,并为牛品种的选育工作供理论依据。[方法]试验随机选取20头30月龄文山高峰牛母牛,测量体重(Y)、体高(X₁)、十字部高(X₂)、体斜长(X₃)、胸围(X₄)、腹围(X₅)、管围(X₆),然后计算体重和体尺性状的变异程度并进行相关性分析、通径分析及逐步回归分析以建立其体重与体尺性状之间的最优回归方程。[结果]文山高峰牛母牛的体重的变异系数最大(9.42%);体重与6项体尺性状均呈极显著正相关(P<0.01),腹围和体重间的相关系数最大(0.924);通径分析结果显示,腹围对体重的直接作用较大,十字部高、体斜长、胸围对体重的间接作用大。[结论]腹围、十字部高、体斜长是影响体重的最主要性状,通过逐步回归分析构建的文山高峰牛母牛体重与体尺之间的最优回归方程为Y=-648.762+0.639X₅...     

Effect of sodium phytate supplementation on fat digestion and cholesterol metabolism in female rats

The effects of sodium phytate supplementation on fat digestion and cholesterol metabolism were investigated in female rats. On the basis of an in vitro experiment showing that phytate raised the solubility of bile acids, it was predicted that phytate feeding would depress faecal bile acid excretion, raise apparent fat digestibility and elevate serum cholesterol concentrations. The experimental diets with or without sodium phytate were either cholesterol-free or cholesterol-rich and had a normal calcium concentration. Rats fed on the cholesterol-rich diet with sodium phytate showed enhanced faecal bile acid excretion, but there was no effect on fat digestibility. In rats fed the cholesterol-free diets, phytate did neither affect fat digestion nor bile acid excretion. Sodium phytate inclusion in the cholesterol-rich diet raised serum cholesterol concentrations, but reduced liver cholesterol concentration. Thus, the in vivo data do not agree with the in vitro observations. Both phytate and cholesterol feeding influenced mineral and trace element metabolism. Liver zinc concentrations were raised by phytate feeding. Cholesterol consumption reduced hepatic concentrations of copper, iron and zinc. Both phytate and cholesterol feeding reduced the apparent absorption of calcium, magnesium and phosphorus.     

12月龄短角牛体重与主要体尺指标的相关性分析

本文旨在探究12月龄短角牛体重与主要体尺指标之间的相关性,构建多元回归方程,研究影响短角牛的主要体尺指标及月龄。选取12月龄公牛163头,母牛261头,共424头短角牛体重、体高、十字部高、体斜长、胸围的体尺数据,使用最小二乘法对已知数据进行最佳线性拟合,构建多元回归方程并分析其相关性。结果显示,12月龄短角公牛的体重与各体尺指标的平均值均高于母牛;且体重与各体尺指标的回归关系达到极显著水平（p﹤0.01）,多元线性回归方程拟合度较高。12月龄短角牛无论公母,其体重与各体尺指标之间均呈现不同程度的相关性, 其中公牛的体高、十字部高、体斜长、胸围与体重的相关性高于母牛。12月龄短角公牛体重与体高、十字部高、体斜长、胸围呈极显著正相关（p﹤0.01）,其中体重与胸围的相关性最大(r=0.902)。12月龄短角母牛的体重与体高、十字部高、体斜长、胸围之间均呈极显著正相关（p﹤0.01）,其中与胸围相关性最大(r=0.823)。12月龄短角牛的体重与体高、十字部高、体斜长、胸围之间均呈极显著正相关（p﹤0.01）,其中与胸围相关性最大(r=0.873)。     

Effect of guanidinoacetic acid supplementation in cattle

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Guanidinoacetic acid (GAA) is a naturally occurring precursor to creatine, an source of energy for skeletal muscle. Feeding GAA to chickens, pigs and cattle improves growth performance through a mechanism that may include increased serum IGF-1 and feed conversion (He et al., 2018; Faraji et al., 2019; Li et al., 2020). The formation of creatine from GAA uses a considerable number of methyl donors, arginine and glycine (Ostojic, 2016). The consequences of feeding GAA to methyl-group deficient cattle was investigated by Ardalan et al (2021). Although GAA increased serum creatine concentrations in both sufficient and deficient animals, protein deposition was most effective when added methionine was included in the diet. Further research is required to better understand the relationship between methyl donor supply, GAA and creatine metabolism.     

Effect of propionate level in a volatile fatty acid salt mixture fed to lambs on weight gain, body composition and plasma metabolites

Chopped hay supplemented with a volatile fatty acid salt mixture at 20% of metabolizable energy (ME) was fed to 30 Suffolk X Corriedale lambs (mean wt 29.6 kg) to determine the effects of dietary propionate on weight gain, body composition and plasma metabolites. Propionate accounted for 0, 25, 50, 75 or 100% of the salt mixture energy, and acetate accounted for the remainder. Each diet was fed at two levels of daily intake (158.7 and 130.6 kcal ME/W.75). Lambs on the high level of intake lost more (P less than .05) energy in feces, lost less (P less than .05) energy in CH4 and had carcasses with more (P less than .10) water and fat than lambs on the low intake level. Percentage of propionate in the salt mixture had no effect on ME or body composition of lambs. Increasing the percentage of propionate in the salt mixture increased plasma propionate in blood samples taken at 1 and 2 h after feeding (linear, P less than .05). Empty body weight gain per megacalorie of ME above maintenance increased as the percentage of propionate in the salt mixture increased, but not until propionate reached 75% of the salt mixture (linear, P less than .05; cubic, P less than .05). These results show that propionate in the blood has a positive, but nonlinear, effect on weight gain, even when energy intake is held constant.     

Short-term effect of antibiotic feeding on site and extent of digestion of growing and finishing diets in feedlot cattle

Two metabolism trials were conducted to evaluate the influence of therapeutic antibiotic supplementation on characteristics of digestion of growing and finishing diets. Treatments consisted of a basal diet supplemented with: no antibiotics, 350 mg chlortetracycline and 350 mg sulfamethazine and 700 mg chlortetracycline and 700 mg sulfamethazine. In trial 1, treatment effects were evaluated in a replicated 3 X 3 Latin-square design experiment involving six crossbred steers (462 kg) with cannulas in the rumen and proximal duodenum. The basal diet contained (dry matter basis) 16.1% alfalfa hay, 72% steam flaked corn, 3.3% molasses, 5.8% fat, .96% urea, .79% limestone, .50% trace mineral salt, 33 mg/kg lasalocid, 2,200 IU/kg vitamin A and .44% chromic oxide. Dry matter intake was limited to 1.4% of body weight. In trial 2, treatment effects were evaluated in a 3 X 3 Latin-square design experiment involving three steers (399 kg) with cannulas in the rumen and proximal duodenum. The basal diet contained (dry matter basis) 10.1% sudangrass hay, 34.9% alfalfa hay, 43.9% steam flaked corn, 6.1% molasses, 4.0% fat, .46% urea, .49% trace mineral salt, 33 mg/kg lasalocid and 2,200 IU/kg vitamin A. Dry matter intake was limited to 1.65% of body weight. Antibiotic supplementation did not influence microbial efficiency, passage of microbial and feed N to the small intestine, or either ruminal or total tract digestion of organic matter and acid detergent fiber in either growing or finishing diets (P greater than .20).(ABSTRACT TRUNCATED AT 250 WORDS)