Aberdeen Angus Steers Research Articles

Influência de suplementos de baixo e médio consumo na fase de crescimento de novilhos mantidos em pastagem tropical e terminados em confinamento

ABSTRACT: The objective was to evaluate the animal production and ingestive behavior of the steers fed different supplements during the growth phase in Aruana grass, and the influence of this supplementation on production performance in feedlot phase. The treatments consisted of three supplements during the growing phase: mineral salt (0.12 g/kg of body weight - BW), low intake energy-protein supplement (1.26 g/kg of BW), and medium intake (3.76 g/kg of BW). Forage canopy characteristics, animal production, and animal behavior on pasture were evaluated in a completely randomized design with three replicates (paddocks). The titanium dioxide marker was used to determine the intake and apparent digestibility during the pasture phase. The production performance in feedlot was evaluated in a completely randomized design with eight replicates (animals). Twenty-four Aberdeen Angus steers (15 ± 1.5 months old; 364.8 ± 21.7 kg BW) were used. At the end of the growth phase the animals were confined and fed a single diet. Dry matter, crude protein, and neutral detergent fiber (NDF) contents of forage and intake were not influenced by the treatments. The average daily gain was higher for the medium intake supplement in pasture phase. The apparent digestibility of NDF (P = and chewing rate were higher for the medium intake supplement. The average daily gain and fat thickness of carcasses were higher for the medium intake supplement in the feedlot phase. The supplements of medium intake increase animal productivity during the growing phase on pastures and cattle’s finishing performance in intensive production systems.

The method of increasing the resistance of young cattle

In the conditions of the Magadan region researches on the use of a feed additive based on seaweeds (Laminaria Bullatelancet-likelargekelp, fucus Fucusevanescens C. Agardh) in combination with lichens (Cladonia alpestris and Cetraria islandica) in the diets of young cattle of mixed cattle were conducted. Experimental and control groups of 15-17-month-old young animals were matched by the pairwise method. The groups included first-generation crossbred Hereford and Aberdeen Angus steers. Young animals of the experimental group received daily feed supplement in addition to the basic diet: kelp in an amount of 120 g/head with lichens 50 g/head/day. The stimulating effect of the supplement on the body is due to the content of a wide range of biologically active substances that are a factor in the growth and development of farm animals and have a positive effect on their immune system. Inclusion of the feed additive into the diets increased the absolute weight gain of the experimental bulls by 5,62 kg, the relative gain by 12,53%, and the average daily gain by 93,8 g (12,55%) as compared to the control bulls (p ≤ 0,001). The relative growth rate according to S. Brody was 1.31% higher in experimental young animals from birth to 17 months of age compared to the control. The use of the feed additive improved the physiological condition and resistance of the young animals of the experimental group. The content of erythrocytes in their blood increased by 0.32 million/μL (5.18%), hemoglobin by 1.1 g/dL (11.48%), and calcium by 0.06 mmol/L (2.37%).

Individual feed intake and performance of finishing steers on ryegrass pasture supplemented with increasing amounts of corn using an automated feeding system

Beef production in subtropical areas is mainly based on extensive grazing systems. During the winter, a drop in the forage quantity is common, energy supplementation may help maintain desired production levels. To measure the effect of increasing levels of corn supplementation on the individual forage intake and feed efficiency of finishing steers, we conducted a 99-d experiment during the winter-spring season in Uruguay. Sixty Aberdeen Angus steers (average BW 464.0 ± 29.7 kg) with access to the same sward of ryegrass (Lolium multiflorum Lam.) were managed under a strip-grazing system (sward height post-grazing: 5 cm) and access to an automated supplement feeder until slaughter. Steers were blocked by BW and previous supplement intake and randomly assigned to one of four groups of 15 animals: control (CON, 0.1% BW of corn), low supplementation (LS, 0.4% BW of corn), moderate supplementation (MS, 0.8% BW of corn), and high supplementation (HS, 1.2% BW of corn). Corn was pelleted with TiO2 to estimate fecal production. Diet digestibility was estimated with acid-insoluble ash concentration. The average daily forage allowance was 3.6 kg DM/100 kg BW per day. Supplement intake was 0.5, 1.8, 3.6, and 4.3 kg DM/d for CON, LS, MS, and HS group, respectively. Corn added at 0.4% BW resulted in a greater (P ≤ 0.01) forage intake than other treatments. A quadratic response was observed for forage (P ≤ 0.05) and total diet (P ≤ 0.01) intake to increasing rations of supplements. Total diet digestibility was greater (P ≤ 0.01) for CON and LS steers than for those from MS and HS; and an inverse, linear relationship with supplementation levels was observed (P ≤ 0.01). Steers grew faster with increasing amounts of supplementation (P ≤ 0.01) in comparison to CON cattle, responding quadratically (P ≤ 0.05) to added corn. Cattle from the CON group showed the lowest hot carcass weight (P ≤ 0.01). Finishing cattle on ryegrass pasture (low post-grazing sward height) using 0.6 to 0.8% BW of corn supplementation is the best option to obtain a better intake, performance, and carcass weight, being an alternative to reduce days on fattening and/or the cost of feeding animals.

Amino acid composition of beef obtained from cattle of beef breeds

The purpose of the research was to study the amino acid composition of beef obtained from beef cattle of Aberdeen Angus and Hereford breeds. The studies were conducted on steers of 12- and 18-month-old of Aberdeen Angus and Hereford breeds. The amino acid content was determined in an average meat sample by high-performance liquid chromatography. Samples for analysis were taken by quartering. It was found that beef obtained from Aberdeen-Angus and Hereford steers of diff erent ages was a complete product in terms of amino acid composition, which was confi rmed by the value of the protein quality index of 5,55–5,73 and 5,34–5,49, the ratio of methionine : tryptophan – 1,22 and 1,23. At the age of 12 months, the protein value of beef was higher in herdmates of Aberdeen-Angus breed by 3,78 % more than in steers of Hereford breed. The diff erence in the ratio of methionine : tryptophan was 0,81 % in favor of Hereford steers. The same content of aspartic acid in meat was found in young animals of 18 months of age of the studied breeds – 2,03 g/100 g. A comparative analysis of the concentration of essential amino acids in beef showed that Hereford steers had more valine, histidine, lysine, threonine and phenylalanine than herdmates of Aberdeen-Angus breed by 3,30; 4,26; 1,11; 7,14 (p < 0,05) and 4,76 %, respectively. The concentrations of valine, isoleucine, methionine and tryptophan were higher in Aberdeen Angus steers than in Hereford herdmates by 3,30; 2,50; 2,00 and 2,50 %, respectively. When analyzing the results of beef studies on the content of dispensable amino acids in 18-month-old steers, the advantage in concentration of alanine, glycine, glutamic acid, serine, tyrosine, cystine was in Aberdeen-Angus steers, the diff erence with the herdmates of Hereford breed was 6,50 (p < 0,05), 2,25; 8,28 (p < 0,05), 56,72 (p < 0,001), 1,10 and 9,09 % (p < 0,05), respectively. The indicator of the protein value of beef was higher in Aberdeen Angus steers by 5,11 %. The difference in the ratio of methionine: tryptophan again amounted to 0,81 % in favor of Hereford steers.

The features of morphological and biochemical blood parameters and linear growth of steers of different origin

The growth of beef production is possible with an increase in the number of young cattle on rearing and fattening. In the Russian Federation over-replacement young cattle of dairy breeds are mainly used for this purpose. However, the transfer of dairy cattle breeding to industrial production technologies has led to a reduction in livestock for fattening. This raises the question of the development of specialized beef cattle breeding and the increase in the number of beef cattle. The purpose of the work was to study the features of morphobiochemical indicators of blood and linear growth of beef steers of diff erent origin. The data on the results of hematological studies of Aberdeen-Angus steers and their crossbreds with Black-and-White breed have been presented in the paper. The changes in the shaped elements and biochemical parameters of the blood by the periods of rearing steers were analyzed. It was found that crossbred animals had higher rates than their purebred herdmates. A higher content of erythrocytes and hemoglobin was observed in crossbred young animals. This indicates more intensive redox processes occurring in the body and its respiratory function, which corresponds to the increase in productivity. It was found that with the age of animals in the experimental groups, there was the decrease in the blood level of hemoglobin and erythrocytes with slight fl uctuations in leukocytes, which is a common biological pattern of growth and development of animals. With a higher level of albumins in the blood, the average daily weight gain was also higher. At 3 months of age, crossbred steers had the highest average daily gains in live weight. They had by 2,3 % higher albumin content than purebred herdmates. A comparative evaluation of the linear growth of experimental steers of the beef productivity direction revealed certain diff erences in the main measurements and conformation indices; a tendency to improve beef forms in crossbred animals was noted.

Selenium-containing drug together with the feed additive Benut in the rations of steers

Currently, there is great interest in the use of selenium drugs in animal husbandry. Chickpea is high-containing in selenium and protein. The feed additive Benut, made on the basis of chickpea, has a high content of selenium. At the same time, its active interaction with proteins was revealed. The purpose of the work was to increase the meat productivity and quality of beef of steers when using the selenium-containing drug DAFS-25 in rations together with the feed additive Benut. In order to conduct the experiment, according to the principle of analogues 3 groups of Aberdeen-Angus steers were formed at the age of 9 months for 15 heads in each group. The duration of the experiment was 172 days including the main period 150 days. In the main period, the steers of the 1st control group received the main ration (MR), the 2nd experimental group received MR + DAFS-25 (1,6 mg/kg of concentrates) and the 3rd experimental group received MR + 0,5 kg/head/day of the feed additive Benut (instead of an equivalent amount of concentrates) + DAFS-25 to ensure the content of selenium as in the ration of animals of the 2nd experimental group. The beef productivity of fattened steers of Aberdeen-Angus breed was studied and also indicators of blood composition, digestibility and assimilation of feed nutrients, beef quality and efficiency of its production, when used in rations of the drug DAFS-25 separately and in combination with the feed additive Benut. Profit from the sale of beef in the 2nd experimental group was received by 84,4 rubles more and in the 3rd experimental group by 574,8 rubles more than in the 1st control group. In the 2nd and 3rd experimental groups the profitability level was 1,2 and 13,2 % higher than in the 1st control group (27,3 %).

From the fatty acid content perspective, is it healthier to eat a hindquarter or a forequarter cut? Angus steers in pasture or concentrate systems

ABSTRACT In this study, Biceps femoris (BF) and Triceps brachii (TB) of Aberdeen Angus steers, from the hindquarter and forequarter, respectively, were compared from their fatty acid composition, lipid health, and lipid enzyme activity indices points of view. For this, ten animals were produced in a pasture system and ten were finished in a concentrate-based system. TB presented a significantly higher intramuscular fat, saturated C14:0, C14:1, C16:1, CLA, and MUFA content. BF presented a significantly higher LA, ARA, EPA, DPA, DHA, PUFA, total n-6, and n-3 content, and a significantly higher PUFA/SFA ratio. Significant differences between muscles were found regarding lipid enzyme activity indices, but not concerning atherogenic and thrombogenic indices. Also, meat from different feeding systems was compared, where meat from pasture presented a better fatty acid composition regarding cardiovascular health aspects. In conclusion, BF presented a better composition in the most nutritionally relevant fatty acids, with exception of CLA.

Oxidative stability, fatty acid composition and health lipid indices of Longissimus dorsi muscle from Aberdeen Angus steers produced in different feeding systems

ABSTRACT: The aim of this study was to evaluate the oxidative and anti-oxidative status of unaged and aged Longissimus dorsi (LD) muscle obtained from a commercial abattoir. Also, fatty acid composition and calculated health lipid indices of meat were compared. Animals slaughtered were Aberdeen Angus steers raised in three typical feeding systems of Uruguay: (1) Pasture (n=10), (2) Pasture + Supplement (P+S) with corn grain (n=10), and (3) Feedlot (n=10). Feeding had no effect on lipid and protein oxidation but the antioxidant enzymes activities were affected as follows: superoxide dismutase (SOD): Pasture, Feedlot > P+S; catalase: Pasture > P+S, Feedlot; glutathione peroxidase (GPx): Feedlot > P+S > Pasture. Total antioxidant potential, determined by Fenton reaction, was higher in aged meat from Pasture compared with aged meat from Feedlot. Meat from Pasture and P+S presented a higher eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and total n-3 content and a lower lipid content, n-6/n-3 ratio and trombogenic index compared to meat from Feedlot. In conclusion, Pasture seems to produce a more resistant meat against induced oxidation processes, particularly after ageing, and a healthier meat together with meat from P+S system, regarding fatty acid composition and lipid indices, compared to Feedlot.

Failure of ivermectin efficacy against Psoroptes ovis infestation in cattle: Integrated pharmacokinetic-pharmacodynamic evaluation of two commercial formulations

Psoroptic mange is an important parasitic disease that mainly affects beef cattle producing marked economic losses. Ivermectin (IVM) is considered one of the most effective treatments against psoroptic mange and is used worldwide to control both endo and ectoparasites in different species. The current work assessed the relationship between pharmacokinetic behavior of IVM and its efficacy against Psoroptes ovis after the subcutaneous administration of two commercial formulations in a cattle feedlot. Aberdeen Angus and Hereford steers were selected based on the presence of active mite infestations. Animals were allocated into 4 experimental groups and treated with a single (day 0) or repeated subcutaneous injection (days 0 and 7) of one of two commercial formulations of IVM (1%) at 0.2 mg/kg. Blood and skin samples were taken from 8 randomly selected animals of each experimental group to measure IVM concentrations by HPLC. Skin scrapings were also collected from six different sites in each animal, mites were counted and ranked based on a density score. Equivalent plasma concentrations of IVM were measured after the administration of IVM formulations under study. The repeated administration of both IVM formulations at day 0 and 7 accounted for a greater plasma drug availability compared with the single administration (P < 0.05). IVM was well distributed from the plasma to the skin without significant differences between both IVM formulations. There was a positive correlation between IVM concentrations in skin and plasma (r: 0.73 P < 0.0001). The mean ratios between IVM availabililty (measured as AUC) in the skin and in plasma were between 1.2 and 2.1. The repeated administration of IVM increased significantly the IVM concentrations in the skin of areas affected by mange. IVM failed to obtain a parasitological cure in the different groups affected by mange. The failure was observed with both formulations administeredat single or repeated doses. Based on the number of animals cured, the range of efficacy was between 0% on day 7 and 60% on day 28 post-treatment. No significant differences in the P. ovis density scores were observed after the IVM treatment at single or repeated doses. Additional studies are needed to confirm the presence of resistant strains of P.ovis and to establish the appropriate measures to control these parasitic infestations in feedlot cattle.

The effect of dietary addition of nitrate or increase in lipid concentrations, alone or in combination, on performance and methane emissions of beef cattle

Adding nitrate to or increasing the concentration of lipid in the diet are established strategies for reducing enteric methane (CH4) emissions, but their effectiveness when used in combination has been largely unexplored. This study investigated the effect of dietary nitrate and increased lipid included alone or together on CH4 emissions and performance traits of finishing beef cattle. The experiment was a 2×4 factorial design comprising two breeds (cross-bred Aberdeen Angus (AAx) and cross-bred Limousin (LIMx) steers) and four dietary treatments (each based on 550 g forage : 450 g concentrate/kg dry matter (DM)). The four dietary treatments were assigned according to a 2×2 factorial design where the control treatment contained rapeseed meal as the main protein source, which was replaced either with nitrate (21.5 g nitrate/kg DM); maize distillers dark grains (MDDG, which increased diet ether extract from 24 to 37 g/kg DM) or both nitrate and MDDG. Steers (n=20/dietary treatment) were allocated to each of the four treatments in equal numbers of each breed with feed offered ad libitum. After 28 days adaptation to dietary treatments, individual animal intake, performance and feed efficiency were recorded for 56 days. Thereafter, CH4 emissions were measured over 13 weeks (six steers/week). Increasing dietary lipid did not adversely affect animal performance and showed no interactions with dietary nitrate. In contrast, addition of nitrate to diets resulted in poorer live-weight gain (P<0.01) and increased feed conversion ratio (P<0.05) compared with diets not containing nitrate. Daily CH4 output was lower (P<0.001) on nitrate-containing diets but increasing dietary lipid resulted in only a non-significant reduction in CH4. There were no interactions associated with CH4 emissions between dietary nitrate and lipid. Cross-bred Aberdeen Angus steers achieved greater live-weight gains (P<0.01), but had greater DM intakes (P<0.001), greater fat depth (P<0.01) and poorer residual feed intakes (P<0.01) than LIMx steers. Cross-bred Aberdeen Angus steers had higher daily CH4 outputs (P<0.001) but emitted less CH4 per kilogram DM intake than LIMx steers (P<0.05). In conclusion, inclusion of nitrate reduced CH4 emissions in growing beef cattle although the efficacy of nitrate was less than in previous work. When increased dietary lipid and nitrate inclusion were combined there was no evidence of an interaction between treatments and therefore combining different nutritional treatments to mitigate CH4 emissions could be a useful means of achieving reductions in CH4 while minimising any adverse effects.

Cooking method effect on Warner-Bratzler shear force of different beef muscles

The aim of this study was to evaluate the effect of oven, griddle plate and water bath cooking on the WBSF values and % cooking loss for longissimus thoracis (LT), semitendinosus (ST), semimenbranosus (SM) and biceps femoris (BF), of Aberdeen-Angus steers. Similar effect of cooking methods on WBSF values were observed for LT, SM and BF steaks. The highest values were observed in oven whereas the lowest were obtained in griddle plate. For ST steaks significant differences of WBSF values were obtained between oven (with the highest value) and the other two methods. Moreover, the cooking methods studied presented differences in the coefficients of variation of WBSF values, which also were different according to the type of muscle for each cooking method. Oven cooking resulted in the highest cooking losses in all muscles.

Compensatory growth in crossbred Aberdeen Angus and Belgian Blue steers: Effects on the colour, shear force and sensory characteristics of longissimus muscle

The effect of feed restriction (99days) followed by compensatory growth during a 200day re-alimentation period on the colour and sensory characteristics of meat from Aberdeen Angus×Holstein-Friesian (AN) and Belgian Blue×Holstein-Friesian (BB) steers was examined. Compensatory growth had no effect on muscle pH and temperature decline, chemical composition, drip loss, fat colour, or juiciness, but increased (P=0.009) Warner-Bratzler shear force and decreased tenderness (P=0.08) and overall liking (P=0.09). Compared to meat from BB steers, meat from AN steers had a higher intramuscular fat concentration and was rated similarly for tenderness, but higher for many of the flavour characteristics examined. While adjustment for intramuscular fat concentration removed some of these differences, genotype-specific flavour differences remained. It is concluded that genotype had greater effects on meat quality than the compensatory growth feeding regime imposed in this study.

Catalase, SOD and GPx Activities in triceps brachii muscle from Aberdeen Angus steers finished on pasture, pasture and concentrate, or concentrate

Three feeding system were investigated to determine if any of them is more suitable to ensure a better antioxidant protection to meat from Triceps brachii muscle of Aberdeen Angus steers. They were finished on pasture, pasture + concentrate with corn grain, or concentrate alone. TBARS, protein carbonyls and antioxidant enzymes activities have been determined in fresh and aged meat (14 days in vacuum, 1-2°C). The level of TBARS ranged between 0.59-0.64 mg MDA/kg meat, whereas levels of protein carbonyl ranged between 0.18-0.22 mmoles DNPH/mg protein. The activities of catalase and superoxide dismutase are higher in fresh meat of animals fed pasture, compared to those finished on pasture and concentrate, or on concentrate alone. Glutathione peroxidase (GPx) showed higher activities in meat of animals finished on concentrate in comparison those finished on pasture and concentrate, or pasture. However, the results of the investigation do not allow the advising, for now, for the most suitable feeding system for finishing steers that help producers to preserve meat from lipids and protein oxidation. More investigations are necessary to highlight the feeding conditions, which could influence the activities of antioxidant enzyme catalase, SOD and GPx in meat.

Influence of Feeding System on Lipids and Proteins Oxidation, and Antioxidant Enzymes Activities of Meat from Aberdeen Angus Steers

Three feeding system were investigated to determine if any of them is more suitable to ensure a better antioxidant protection to meat. Animals were produced on pasture, pasture supplemented with corn grain, or feedlot. TBARS, protein carbonyls and antioxidant enzyme activities have been determined in fresh ad aged meat from Biceps femoris of Aberdeen Angus steers. No feeding system showed clear protection against lipids and protein oxidation in fresh meat. However, aged meat suffer always lipids and protein oxidation independently of the feeding system. There is not a clear pattern of the action of the catalase antioxidant enzyme (no significant main effect). However, pasture based feeding system present a lower SOD (0.96 UI) and GPx (9.22 nmoles/min/mg protein) activity, versus feedlot (1.12 UI and 11.48 nmoles/min/mg protein, respectively). Based on the results of the present investigation, it seems difficult to conclude about the best feeding system advised to minimize the lipids and protein oxidation of meat.

Performance and ultrasound measurements of beef cattle fed diets based on whole corn or oats grains

This study intended to contrast dietary effects of whole grain oats versus corn included in rations with moderate roughage content on animal performance, beef ultrasound measurements, rumen and blood parameters. Ten Aberdeen Angus steers (203 kg) in individual pens were fed twice daily on either whole oats (OD) or corn (CD) based diets. Measurements were: DM intake (DMI), average daily gain (ADG), feed to gain ratio (F/G); back fat (BF) and rib eye area (RA); blood parameters. Four cannulated steers were used to study rumen pH, NH3-N and grain degradability. Rations dietary components were 55% grain, 30.1% barley straw, and 10.6% whole soybeans. Despite calculated higher ME supply (P = 0.0887) no differences were found for DMI, ADG, or F/G. Metabolizable protein intake (19.4%) was larger and degradable protein intake (43.3%) smaller for CD compared with OD (P < 0.01). The growth rate (cm2 d-1) for RA was 40% grater for OD, but larger BF deposition (P = 0.0787) was found for CD. Blood Mg was higher for OD (p = 0.0564), nevertheless other blood parameters remained unaffected. Rumen pH and NH3-N were not influenced by diet, variations were only observed within time periods. Rumen pH decreased linearly from 7.05 to 6.13 and 7.11 to 6.37 for OD and CD respectively (P < 0.05). Minimum NH3-N concentrations (mg dL-1) were reached 12 and 18 h after morning meal for OD (7.10) and CD (5.82) respectively. Rumen degradation was larger for oats than corn. Whole oats rather than corn fed up to 55% of total DM seems to improve protein deposition, without significant changes in animal performance, rumen environment or blood parameters.

Carcass characteristics and meat quality of Aberdeen Angus steers finished on different pastures

The present study was conducted to assess carcass features, physicochemical and sensory parameters of meat from steers finished on three types of pastures: natural pasture; natural pasture improved, fertilized and oversown with winter species; and annual summer grassland. The experiment was conducted from December 14, 2009 to November 30, 2010, with treatments distributed in a completely randomized design with a different number of replicates. Animals were used as experimental units. Experimental animals were Aberdeen Angus steers with twenty months of initial age and 354±27.4 kg of live weight, on average. The highest average daily gains were obtained for the annual summer grassland. There was no effect of treatments on carcass conformation. The highest carcass yield was obtained on the improved natural pasture. Forequarter yield, side cut yield and longissimus muscle area were similar between the pastures. Moisture and total lipids were not affected by the pasture. Thawing and cooking losses were higher in improved natural pasture and lower in sorghum pasture. Regardless of the treatment, the meat had luminosity ranging from intermediate to dark, high in red, high in yellow, and considered within the normal range for beef. Meat of higher shear force was found in natural pasture, and lower shear force was observed in meat from annual summer grassland. Average live weight daily gain explained 18% of the shear force. Sensory evaluation by duo-trio test showed differences between samples from distinct pastures in flavor. All the studied systems allow for desirable characteristics in carcass and meat.

Effect of sire breed and genetic merit for carcass weight on the transcriptional regulation of the somatotropic axis in longissimus dorsi of crossbred steers1

The somatotropic axis plays an important role in postnatal growth, development, and differentiation of skeletal muscle. The aim of this study was to examine the effect of sire breed and sire EPD for carcass weight (EPD(cwt)) on the expression of components of the somatotropic axis in LM of beef cattle at slaughter. Crossbred Aberdeen Angus (AA; n = 17) and Belgian Blue (BB; n = 16) steers born to Holstein-Friesian dams and sired by bulls with either high (H) or low (L) EPD(cwt) were used in the study. Thus, there were 4 genetic groups [i.e., BBH (n = 8), BBL (n = 8), AAH (n = 8), and AAL (n = 9)]. Blood samples were collected via jugular venipuncture at regular intervals for analysis of plasma concentrations of IGF-1 and insulin. Total RNA was isolated from LM collected at slaughter, and the mRNA expression of IGF-1, IGF-2, their receptors (IGF-1R; IGF-2R), 6 IGFBP, acid labile subunit (ALS), and GH receptor (GHR) was measured by real-time reverse-transcription quantitative PCR. There was no effect of either sire breed or EPD(cwt) on concentrations of circulating IGF or insulin (P > 0.05). Gene expression of IGF-1R and IGFBP3 was upregulated in AA (P < 0.001) compared with BB, whereas IGF-1 was upregulated in H compared with L animals (P < 0.01). Correlation analysis indicated moderate positive associations between gene expression of IGFBP3 and IGF-1 (r = 0.54; P < 0.001) and IGF-1R (r = 0.48; P < 0.01). In addition, correlation analysis revealed that mRNA expression of IGFBP3 was moderately negatively associated with LM area per kilogram of carcass weight (r = -0.40; P < 0.05). Greater gene expression of IGF-1 and reduced transcript abundance of IGFBP3 in muscle may have a role in increased muscle growth potential in steers during the finishing period. These data will contribute to a better understanding of the molecular control of muscle growth at a tissue level in cattle.

Effect of linseed oil and fish oil alone or as an equal mixture on ruminal fatty acid metabolism in growing steers fed maize silage-based diets1

Because of the potential benefits to human health, there is interest in increasing 18:3n-3, 20:5n-3, 22:6n-6, and cis-9,trans-11 CLA in ruminant foods. Four Aberdeen Angus steers (406 ± 8.2 kg of BW) fitted with ruminal and duodenal cannulas were used in a 4 × 4 Latin square experiment with 21-d periods to examine the potential of fish oil (FO) and linseed oil (LO) in the diet to increase ruminal outflow of trans-11 18:1 and total n-3 PUFA in growing cattle. Treatments consisted of a control diet (60:40; forage:concentrate ratio, on a DM basis, respectively) based on maize silage, or the same basal ration containing 30 g/kg of DM of FO, LO, or a mixture (1:1, wt/wt) of FO and LO (LFO). Diets were offered as total mixed rations and fed at a rate of 85 g of DM/(kg of BW(0.75)/d). Oils had no effect (P = 0.52) on DMI. Linseed oil had no effect (P > 0.05) on ruminal pH or VFA concentrations, whereas FO shifted rumen fermentation toward propionate at the expense of acetate. Compared with the control, LO increased (P < 0.05) 18:0, cis 18:1 (Δ9, 12-15), trans 18:1 (Δ4-9, 11-16), trans 18:2, geometric isomers of 9,11, 11,13, and 13,15 CLA, trans-8,cis-10 CLA, trans-10,trans-12 CLA, trans-12,trans-14 CLA, and 18:3n-3 flow at the duodenum. Inclusion of FO in the diet resulted in greater (P < 0.05) flows of cis-9 16:1, trans 16:1 (Δ6-13), cis 18:1 (Δ9, 11, and 13), trans 18:1 (Δ6-15), trans 18:2, 20:5n-3, 22:5n-3, and 22:6n-3, and decreased (P < 0.001) 18:0 at the duodenum relative to the control. For most fatty acids at the duodenum, responses to LFO were intermediate of FO and LO. However, LFO resulted in greater (P = 0.04) flows of total trans 18:1 than LO and increased (P < 0.01) trans-6 16:1 and trans-12 18:1 at the duodenum compared with FO or LO. Biohydrogenation of cis-9 18:1 and 18:2n-6 in the rumen was independent of treatment, but both FO and LO increased (P < 0.001) the extent of 18:3n-3 biohydrogenation compared with the control. Ruminal 18:3n-3 biohydrogenation was greater (P < 0.001) for LO and LFO than FO, whereas biohydrogenation of 20:5n-3 and 22:6n-3 in the rumen was marginally less (P = 0.05) for LFO than FO. In conclusion, LO and FO at 30 g/kg of DM altered the biohydrogenation of unsaturated fatty acids in the rumen, causing an increase in the flow of specific intermediates at the duodenum, but the potential of these oils fed alone or as a mixture to increase n-3 PUFA at the duodenum in cattle appears limited.

Desempenho e características de carcaça de novilhos terminados em pastagem de aveia preta e azevém anual com diferentes níveis de suplementação energética

Foi avaliado o efeito da suplementação energética sobre o desempenho e as características de carcaça de 24 novilhos cruza Aberdeen Angus x Charolês terminados aos 24 meses em pastagem de azevém anual (Lollium multiflorum L.) e aveia (Avena strigosa Schreb) manejada em condições de oferta de forragem não limitante ao desempenho animal. Os tratamentos foram níveis de 0; 0,4; 0,8 e 1,2% PV de oferta de concentrado à base de milho moído e minerais. Os animais foram abatidos à medida que atingiram um mínimo de 4,5mm de espessura de gordura na garupa (P8), avaliado por meio de ultrassonografia. Não foram observadas diferenças significativas sobre a deposição de gordura, avaliada in vivo por ultrassonografia ao final da etapa de desempenho, e sobre o ganho médio diário, que apresentaram valores médios de 3,9mm e 1,54kg d-1, respectivamente. A avaliação dos parâmetros bioquímicos séricos evidenciou redução linear dos níveis de ureia e aumento linear para os níveis de colesterol, sem que diferenças significativas fossem observadas sobre os níveis de glicose e triglicerídios. A suplementação produziu incremento linear no rendimento de carcaça e no ganho médio diário de carcaça. Entretanto, não foram observadas diferenças significativas sobre a área de olho de lombo, o peso de abate e o peso de carcaça quente, que apresentaram valores médios de 67,85cm², 438,95kg e 227,75kg. Os níveis crescentes de suplementação utilizados produziram incremento no rendimento e ganho médio diário de carcaça, sem alterações significativas sobre os demais parâmetros de desempenho e carcaça avaliados.

Assessing beef carcass tissue weights using computed tomography spirals of primal cuts

More than 800 beef primal cuts from 44 Aberdeen Angus and Limousin-cross steers carcasses were scanned using spiral computed tomography (CT) and dissected. Thresholds for the segmentation of fat, muscle and bone in the CT spirals were estimated with the objective of assessing the weight of these tissues in the primal cuts and in the entire carcasses. Thresholds were estimated using half of the dataset (DBE) and then validated in the other half (DBV). Automatic image analysis procedures were used to assess tissue weights. The R 2 of the regression between primal tissue weight by dissection and CT were high in both datasets for fat (DBE, 0.89; DBV, 0.92), muscle (DBE, 0.99; DBV, 0.99) and bone (DBE, 0.95; DBV, 0.97). The estimation of total carcass tissue weights were also very accurate for the three tissues ( R 2 values of 0.95 to 0.96), indicating that CT scanning may deliver very accurate information on beef carcass composition faster and with lower cost than physical dissection and without damaging or depreciating the primal joints.