Estimates of genetic parameters for fatty acids in brisket adipose tissue of Canadian commercial crossbred beef steers

Heritability and genetic and phenotypic correlations between 15 individuals and 10 groups of fatty acids with a concentration greater than 0.5% in the brisket adipose tissue of 223 Angus and Charolais based crossbred commercial steers were estimated using univariate and bivariate animal models. Individual saturated fatty acids were low to moderately heritable, with heritability estimates ranging from 0.05 (C16:0) to 0.31 (C15:0). Individual monounsaturated fatty acids were low to moderately highly heritable ranging from 0.04 (9c C17:1 and 11c C18:1) to 0.51 (9c C14:1). Polyunsaturated fatty acid C18:2n-6 was moderately heritable (0.17). Among groups of fatty acids, heritability estimates ranged from 0.03 for branched chain fatty acid (BCFA) and n-6/n-3 to 0.16 for n-6 and Health Index. A range of low (0.00) to high (1.00) phenotypic and genetic correlations was observed among the 25 fatty acids considered in this study. In general, fatty acids such as conjugated linoleic acid (CLA) and 11t C18:1, with potential health benefits, showed significant antagonistic correlations with unhealthy fatty acids such as C14:0 and C16:0. The results from this study provide insight into the direct genetic control of host genes on fatty acid composition of beef tissues and will facilitate designs of genetic selection and/or genetic based diet management to improve fatty acid composition in beef cattle.

Effects of replacing barley grain with triticale-based dried distillers’ grains with solubles on nutrient digestibility, lamb growth performance and carcass traits

The objective of this research was to determine the effects of increasing proportions of triticale-based dried distillers’ grains with solubles (TDDGS) in the diet on nutrient digestibility, growth and carcass traits of lambs. The control diet contained 72.5% barley grain, 10.0% beet pulp, 9.0% sunflower hulls, 3.0% alfalfa meal and 5.5% mixed supplement, which contained molasses, calcium carbonate, minerals and vitamins. Treatment diets contained TDDGS in place of barley grain at 20, 40 or 60% of diet dry matter (DM). In a growth study, 60 weaned lambs stratified by live weight (26.6 ± 3.6 kg) were fed one of the four diets to slaughter weight. Additionally, a digestibility study using these diets in a replicated 4 × 4 Latin square design was conducted using 12 ram lambs. Increasing dietary allocation of TDDGS in the diet did not affect (P > 0.12) DM intake, average daily gain or feed efficiency (feed:gain). At slaughter, cold carcass weight and grade rule scores responded quadratically (P = 0.04) to increasing TDDGS in the diets. Feeding TDDGS did not affect other carcass traits (P > 0.22). Total saturated fatty acids and monounsaturated fatty acids in subcutaneous fat were unaffected by TDDGS, whereas polyunsaturated fatty acids increased linearly (P = 0.03). Concentration of t10, c12-conjugated linoleic acid (CLA) in carcass fat increased linearly (P = 0.02) with increasing TDDGS, but there was no effect (P ≥ 0.20) on concentrations of c9, t11-CLA or t11-18:1. In the digestibility study, DM intake increased linearly (P < 0.01) with increasing TDDGS in the diet, whereas digestibility of DM, crude protein and fat responded quadratically (P < 0.01). Starch digestibility decreased and ADF digestibility increased linearly (P < 0.01), but there was no treatment effect on NDF digestibility (P > 0.29). Total nitrogen, total phosphorus and soluble phosphorus excretion increased (P < 0.01) with increasing TDDGS. In conclusion, TDDGS can be fed in place of barley grain at levels up to 60% in diets for lambs without adverse affects on growth performance or carcass traits, but this practice will lead to an increase in N and P excretion into the environment.Key words: Lamb, digestibility, triticale distillers grains, performance, carcass characteristics

Effects of corn-, wheat- or triticale dry distillers’ grains with solubles on in vitro fermentation, growth performance and carcass traits of lambs

The objective of this study was to determine the effect of replacing a mixture of canola meal and barley grain with corn-, wheat- or triticale dry distillers’ grains with solubles (DDGS) at 20% of dietary dry matter (DM) on in vitro ruminal fermentation in bovine ruminal fluid and on growth performance and carcass characteristics of lambs. Sixty ram lambs (22.6 ± 3.0 kg) were randomly assigned to one of four dietary treatments and given individual ad libitum access to feed until they attained slaughter weight. The control diet consisted (DM basis) of 54% barley grain, 16% sunflower hulls, 11.5% beet pulp, 10% canola meal, 2.5% canola oil and 6.0% molasses, vitamins and minerals mixture. For the three DDGS dietary treatments, 10% barley grain and 10% canola meal were replaced with 20% corn-, wheat-or triticale-DDGS. The source of DDGS did not influence (P > 0.51) dry matter intake (DMI) or average daily gain (ADG). Feed conversion (feed:gain) of lambs fed wheat DDGS was approx. 12% poorer (P < 0.05) than that of lambs fed control or corn DDGS diets. In vitro data suggest that the inefficient gain may have been attributable to greater (P < 0.05) ammonia concentration at 24 h and lower digestibility of wheat DDGS. Carcass traits, including hot carcass weight, body wall thickness and saleable meat yield, were not affected (P > 0.60) by dietary treatment. Total saturated, monounsaturated and polyunsaturated fatty acids in subcutaneous fat were also not affected by DGGS source (P ≥ 0.13). There was no treatment effect (P = 0.33) on concentrations of t11-18:1, but feeding triticale DDGS increased the concentration (P = 0.04) of c9, t11-conjugated linoleic acid (CLA). In conclusion, DDGS from corn, wheat or triticale can replace a mixture of barley grain and canola meal at 20% of dietary DM without adversely affecting DMI, ADG or carcass characteristics of growing lambs, although wheat DDGS may reduce feed conversion ratio (feed:gain). Including triticale DDGS may also improve the fatty acid profile of subcutaneous fat.Key words: Lamb, corn, wheat, triticale, distillers’ grains, performance, carcass characteristics

Association analyses of a SNP in the promoter of IGF1 with fat deposition and carcass merit traits in hybrid, Angus and Charolais beef cattle

A SNP in the promoter region of insulin like growth factor-1 (IGF1) (c.-512C>T) was analysed for associations with 10 fat deposition and carcass merit traits in hybrid (n = 455), Angus (n = 204) and Charolais (n = 186) beef cattle populations. Significant associations of the SNP were found for ultrasound backfat thickness (P = 0.030), carcass average backfat (P = 0.015) and carcass lean meat yield (LMY) (P = 0.023) in the Angus beef population, with the 'CC' genotype showing higher fat depth and lower LMY than the 'TT' genotype. Analyses of transcription factor binding sites based on transcription element search system prediction revealed that the 'C' allele introduces a binding site for nuclear factor I, which has an adipose tissue-specific regulatory role and thus may contribute to the SNP effect on fat deposition in the population of pure Angus cattle, a breed with greater fat depth than the hybrid and Charolais breeds.

Mature adipocytes may be a source of stem cells for tissue engineering

Adipose tissue contains a large portion of stem cells. These cells appear morphologically like fibroblasts and are primarily derived from the stromal cell fraction. Mature (lipid-filled) adipocytes possess the ability to become proliferative cells and have been shown to produce progeny cells that possess the same morphological (fibroblast-like) appearance as the stem cells from the stromal fraction. A closer examination of mature adipocyte-derived progeny cells may prove to be an emerging area of growth/metabolic physiology that may modify present thinking about adipose tissue renewal capabilities. Knowledge of these cells may also prove beneficial in cell-based therapies for tissue repair, regeneration, or engineering.

PPARgamma and GLUT-4 expression as developmental regulators/markers for preadipocyte differentiation into an adipocyte

In this document, we have integrated knowledge about two major cellular markers found in cells of the adipocyte lineage (an adipogenic marker and a metabolic marker). This review provides information as to how differentiation of a cell (such as an adipofibroblast, fibroblast or preadipocyte) to become a viable (and new) adipocyte is under different regulation than that experienced by an immature adipocyte that is just beginning to accumulate lipid. The differentiation, prior to lipid-filling, involves PPARgamma. Subsequently, lipid-filling of the adipocyte relies on a late subset of genes and, depending on depot specificity, involves GLUT-4 or any number of other metabolic markers.

Effect of prebreeding maintenance diet on subsequent reproduction by artificial insemination in alpine and Saanen goats

The objective of this study was to investigate the effect of 2 levels of prebreeding nutrition on reproduction in yearling does artificially inseminated (AI) by the intrauterine laparoscopic method. Forty-two does (Alpine = 22 and Saanen = 20) were randomly penned in groups of 7 and were fed 1 of 2 diets. The diets contained 3.2 Mcal DE/d (MAINT) or 3.5 Meal DE/d (HIGH), which was 10 and 20% higher than the National Research Council recommendations for maintenance requirements. The does were on the 2 feed treatments for 8 wk, after which the MAINT group was switched to the HIGH group diet. A week later, they were fitted with Veramix sponges to synchronize estrus. The sponges were removed from 22, 10 and 10 randomly picked does after 17, 22 and 23 d, respectively. All the does showed estrus within 48 h of removing the sponges. Previously frozen Alpine or Saanen semen (0.5 ml) was deposited into the uterus of does exhibiting standing estrus after anesthetizing them with zylazine and ketamine. Pure breeding was practiced. All the does lost weight prior to breeding. Seventeen does (41%) conceived and kidded by AI while the rest returned to estrus about 23 d later. A significant difference (P < 0.05) in the kidding percentage was observed between the 2 breeds (Alpine = 64% and Saanen = 16%), while the kidding percentage between the 2 diets did not differ (P > 0.05). Of the does that kidded, seven (41%) had singletons, eight (47%) had twins, one had triplets and one had quadruplets. Average litter size (kids/doe kidding) by AI was 1.76. Although the does lost weight prior to breeding, this did not affect their reproduction.

Residual metabolizable energy intake and its association with diet and test duration

The objective was to determine if end-of-test residual metabolizable energy intake (RMEI) is correlated with RMEI values calculated earlier in the test on steers fed two forage (silage) or four forage-grain diets. As the days on test increased the variation in RMEI decreased in all diets. In all but the 85% alfalfa + 15% barley grain diet, test duration for RMEI may be reduced from 105 to 84 d. In the 100% alfalfa silage diet, it may be further reduced from 105 to 63 d (Spearman r = 0.90; Pearson r = 0.94; P < 0.01). The duration of testing required to obtain reliable estimates of RMEI may therefore also depend on the type of diet being fed. Key words: Residual metabolizable energy intake, crossbred steers, correlations, forage-grain diets, test duration

Dietary manipulation to increase conjugated linoleic acids and other desirable fatty acids in beef: A review

The diet is the source of many essential fatty acids such as linoleic and linolenic acids for all mammals. These fatty acids either, as altered isomers or as other elongated products, have been found to provide unique advantages to human health. Currently two conjugated linoleic acids (CLA) isomers (cis-9, trans-11 C18:2; trans-10, cis-12 C18:2) and two elongated products of linolenic acid [eicosapentaenoic acid (EPA, C20:5 n-3), docosahexaenoic acid (DHA, C22:6 n-3)] have been recognized for their roles in maintaining human health. Consumers can obtain these functional fatty acids from beef if the feeding management of beef cattle can be altered to include precursor fatty acids. Diet, breed, and gender are important factors that affect total fat content and/or the fatty acid profile of beef with regard to CLA, EPA, and DHA. Diet provides the precursor fatty acids that are altered and deposited, and breed dictates, the amount of fat that is deposited. These fatty acids can be increased in beef by increasing the forage:concentrate ratio, inclusion of non-fermented forage, and supplementation with various oils or oil seeds. The CLA and vaccenic acid (trans-11 C18:1) concentration in beef was increased by feeding sunflower oil or seeds, linseed, and soybean oil supplemented diets, while cattle fed linseed and fish oil supplemented diets had increased concentrations of EPA and DHA. Although the concentration of these fatty acids can be increased in beef, there is a need to further the understanding of the mechanism by which they exert positive affects on human health. Key words: Cattle, beef, fatty acids, conjugated linoleic acid, eicosapentaenoic acid, docosahexaenoic acid

Effects of feeding high energy or high energy-protein diets to goats

Growth, efficiency and carcass traits were evaluated for goats fed barley or a concentrate mix (CM). Goats on the CM showed higher (P < 0.01) average daily gain (ADG) (27.5%), end of test weight (11.6%), hot carcass weight (HCW) (14.9%) and rib-eye area (REA) (14.7%), lower (P < 0.02) concentrate to gain ratio (CG) ratio (22.5%) and no differences (P > 0.05) in concentrate intake (CI) and dressing percent (DP), compared to those on barley. Although feeding the CM improved ADG, CG, HCW and REA, it may be relatively more economical to finish goats on whole barley grain. Key words: Goat, high energy, high protein, growth, rib-eye area

Growth response of pastured Simmental calves to a high by-pass protein creep supplement

One hundred and thirty-seven cow-calf pairs on pasture in southeastern Alberta, were randomly allocated to one of two treatments no supplement (NOS) or a high by-pass protein (70% of CP) creep supplement (HPS) at an intake of 1.5 kg head−1 d−1. Calf weaning weights and pre-weaning ADG were higher (P < 0.01) in calves fed HPS (306.0 kg and 1.49 kg d−1) compared with NOS (298.2 kg and 1.41 kg d−1), respectively. However, it was uneconomical to feed this high by-pass creep as the feed cost of a kg of additional gain at weaning was $9.60. Key words: Creep supplement, pasture, growth, beef cattle

Relevance of National Research Council feed composition tables in Alberta

The nutrient concentrations of selected Alberta-grown whole barley grain (Hordeum vulgare L.), three pure hays of alfalfa (Medicago sativa L.), barley, oat (Avea sativa L.), and four pure crop silages of alfalfa, barley, corn (Zea mays L.), and oat were determined and compared with nutrient concentrations of similar forages and a cereal grain reported in the National Research Council (NRC 1984 and 1989) feed nutrient composition tables. In addition, the variations in nutrient concentrations within the selected Alberta feedstuffs were assessed as an indication of whether the feedstuffs should be analysed frequently for certain nutrients. The concentrations of zinc and copper in barley grain cultivated in Alberta were 248% and 60% of the NRC values, respectively. The phosphorus, manganese, sulphur, magnesium, CP, selenium and calcium concentrations in barley hay were 17, 18, 18, 22, 32, 50 and 100% higher than NRC values. However, the concentrations of Cu and Zn were only 18 and 40% of the NRC values. Data from the present study suggest that Alberta hays, silages and barley grain are different in nutrient concentrations from similar grain and forages reported by the NRC (1984, 1989). Due to a high percentage of Alberta feeds being below the suggested NRC requirement levels of the various trace minerals, use of NRC table values for Cu, Mn, Mg and Zn for barley hay, silage and grain, oat hay and silage, alfalfa hay and silage and corn silage could result in deficiencies of these trace minerals in beef and dairy cattle with possible adverse effects on productivity. Thus, there is a need to use Alberta-derived nutrient composition values for these elements in diet formulations for cattle in Alberta. The high CVs calculated for most of the nutrients in the selected Alberta feeds suggest that these feeds should be analysed more often in order to minimise costs of production due to nutrient shortfalls or excesses in diets formulated using nutrient values without the knowledge of variability in feed composition. Key words: Nutrient composition, variability, feedstuffs

Pituitary adenylate cyclase-activating polypeptide (PACAP) stimulates exocrine pancreas in conscious preruminating calves

The effects of new hypothalamic peptides, PACAP-27 and PACAP-38, and secretin and VIP on the interdigestive pancreatic secretion and duodenal myoelectric activity during the asecretory phase of the pancreatic interdigestive cycle, compared with the milk ingestion phase, were examined in five calves. Peptides were infused for 5 min into the external jugular vein (0, 3, 10, 30 and 100 pmol/kg body wt during the asecretory phase of the pancreatic interdigestive cycle, and the pancreatic secretory response was compared with that obtained during milk ingestion. Intravenous infusion of PACAP-27 caused dose-related stimulation of pancreatic juice flow and bicarbonate and protein output; this effect was identical to infusion of secretin. The effect of PACAP-38 was less pronounced, and that of VIP was the weakest. Pancreatic juice volume and bicarbonate responses during milk ingestion were similar to responses obtained with the highest doses of hypothalamic peptides and secretin, whereas postprandial protein secretion was much greater than the secretion stimulated with peptides. It was concluded that PACAP from the VIP/secretin family may stimulate pancreatic exocrine secretion in conscious calves and a part of the pancreatic response to food intake can be mediated by PACAP.