Our objectives were 2-fold: to determine the effect of dietary linoleate on milk fat composition and on transcript abundance of acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), lipoprotein lipase (LPL), and stearoyl-CoA desaturase (SCD) mRNA in mammary tissue, and to evaluate milk somatic cell mRNA as a source of mammary tissue mRNA for these enzymes. Eighteen primiparous, crossbred beef cows (BW = 411 +/- 24 kg; BCS = 5.25) were offered Foxtail millet hay at 1.68% of BW daily and either a low-fat control (n = 9) or a high-linoleate (79% 18:2n-6), cracked safflower seed supplement (n = 9). Diets were isonitrogenous and isocaloric, and the linoleate diet contained 5.4% of DMI as fat. At slaughter (37 +/- 3 d postpartum), mammary tissue was sampled and immediately frozen in liquid N2 before being stored at -80 degrees C. Milk samples were obtained from the same mammary glands and immediately centrifuged at 1,200 x g to pellet somatic cells. A ribonuclease protection assay was used to quantify the mRNA in the mammary gland and milk somatic cells. Effects of diet, tissue, or their interaction were not observed for ACC (P = 0.28, 0.89, and 0.35, respectively), FAS (P = 0.38, 0.66, and 0.20, respectively), LPL (P = 0.09, 0.15, and 0.43, respectively), or SCD (P = 0.45, 0.19, and 0.29, respectively). Dietary effects on fatty acid profile of the milk fat suggested that linoleate supplementation might have decreased de novo lipogenesis while increasing uptake of dietary fatty acids; this effect was consistent with a trend toward greater LPL mRNA for linoleate-fed cows (P = 0.09). Correlations (r values) between mammary tissue and milk somatic cell data for each mRNA for the low-fat control diet were: ACC, 0.76 (P = 0.02); FAS, 0.69 (P = 0.04); LPL, 0.68 (P = 0.04); and SCD, 0.73 (P = 0.05), and for the linoleate diet were: ACC, 0.85 (P = 0.003); FAS, 0.75 (P = 0.02); LPL, 0.90 (P = 0.001); and SCD, 0.73 (P = 0.03). We conclude that milk somatic cells obtained from lactating beef cows can be used as a source of RNA to study nutritional regulation of mammary gland lipogenesis in cows fed dietary fat supplements.

Three methods are widely used in the United States to detect the presence of central nervous system (CNS) tissue in meat products: the fluorescent enzyme-linked immunosorbent assay (F-ELISA), developed in this laboratory, the colorimetric Ridascreen Risk Material 10/5 ELISA (R-ELISA), and the U.S. Department of Agriculture, Food Safety and Inspection Service immunohistochemical (IHC) procedure. These assays are based on the immunological detection of glial fibrillary acidic protein (GFAP), a neural antigen largely restricted to the CNS. The objective of the current study was to compare the sensitivity and repeatability of these tests for detecting the presence of neural tissue in meat. Ground beef spiked with 0.05 to 0.5% of bovine brain, spinal cord (SC), or dorsal root ganglia, as well as advanced meat recovery samples, were evaluated by each of the three GFAP detection procedures. Interassay coefficients of variation for the F-ELISA GFAP standards were 7 to 25%, and intra-assay variation due to sampling and extraction of spiked ground beef was 7 to 13% for SC and 8 to 14% for brain (n = 10). The F-ELISA was the most sensitive of the methods tested, capable of detecting 0.3 ng GFAP standard per well and the presence of 0.05% brain and SC in meat. The R-ELISA standards produced highly variable results (up to 36% variation) and, as a result, none of these standards were different from zero (n = 26). The R-ELISA resulted in high sample variation in SC-spiked ground beef samples (coefficients of variation were 23 to 50%) and did not detect the presence of brain contamination. After modification of the R-ELISA sampling and extraction methods, SC-spiked sample variation was reduced to 16 to 20%, and sensitivity was improved from 0.3 to 0.2% SC, although brain tissue was still not detected. The IHC analysis of CNS-adulterated ground beef had a sensitivity of 0.2% SC and 0.05% brain, with false-negative rates of 10 to 20% at and above the stated sensitivities. None of the methods examined detected dorsal root ganglia contamination. The F-ELISA detected the presence of CNS contamination in 20% of the advanced meat recovery samples, compared to 3.5 to 5% for the R-ELISA and 2% for IHC. This study suggests that the F-ELISA is much more sensitive and repeatable than either the R-ELISA or the IHC procedure method for the detection of CNS tissue in meat products.

This chapter examines the biochemistry, mechanism of action and metabolic effects of growth hormone (GH) and then outlines the Insulin-like growth factor (IGF)-system and its physiological effect on farmed animals. Also highlighted in this chapter are studies on the effect of GH and IGF-1 in treatment of animals. Other topics discussed are: the GH molecule, somatomedins, IGF genes and molecules, IGF receptors, IGF binding proteins, effects of GH on farm animal production and the development of transgenic animals.

Our objective was to compare mRNA levels for acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), lipoprotein lipase (LPL) and stearoyl- CoA desaturase (SCD) extracted from mammary gland and from somatic cell pellets of the milk from each mammary gland. Eighteen primiparous beef cows (BW = 411 ± 24.3 kg.; BCS = 5.25) were fed Foxtail millet hay at 2.13% of BW and either a low-fat control (CON; n = 9) or a cracked high-linoleate (67% 18:2 n-6) safflower seed supplement (LIN; n = 9). Diets were isonitrogenous and isocaloric, and the LIN diet contained 5% of DMI as fat. At slaughter (37 ± 3 d postpartum) mammary tissue was sampled and immediately frozen in liquid N2 before being stored at -80oC. Milk samples were obtained from the same mammary glands and immediately spun at 1,200 × g to pellet somatic cells. Ribonuclease protection assay was used to quantify the mRNA. Data were analyzed for a 2 × 2 factorial experiment to test for dietary, tissue and interactive effects. Dietary, tissue, and interactions were not observed for ACC (P = 0.21; 0.91; and 0.45, respectively), FAS (P = 0.32; 0.71; and 0.28, respectively), LPL (P = 0.09; 0.15; and 0.43, respectively), or SCD (P = 0.34; 0.26; and 0.37, respectively). Correlation analysis was performed between mammary tissue and milk somatic cell data within dietary treatment for each mRNA. Within the CON treatment, Pearson correlation coefficients were: ACC, 0.75 (P = 0.02); FAS, 0.69 (P = 0.04); LPL, 0.69 (P = 0.04); and SCD, 0.67 (P = 0.05). Within the LIN treatment, Pearson correlation coefficients were: ACC, 0.85 (P = 0.004); FAS, 0.75 (P = 0.02); LPL, 0.90 (P = 0.001); and SCD, 0.73 (P = 0.03). We conclude that using milk obtained from lactating beef cows can be used as a source of RNA to study regulation of mammary gland lipogenesis.

This chapter discusses the behavioural response as well as response to stress in farm animals under different challenges such as environmental challenges or attack by predators or a mating competitor. The chapter focused on the role of central nervous system (CNS), the autonomic nervous system and the endocrine system in ensuring survival to stress of animals. Other topics include: the autonomic nervous system and the adrenal medulla, adrenergic receptors, beta-adrenergic agonists, effects of beta-adrenergic agonists on growth and body composition.

This chapter presents an outline on the effects of hormones on calcium homeostasis and focused on the regulation of bone growth and differentiation by hormones and growth factors in farm animals.

The hormonal control for growth and development of the three tissues (muscle, bone, and fat) that are essential to the whole development of the body and composition in farmed animals is discussed. This chapter also highlighted the following topics: embryonic development and cell differentiation, cell proliferation and differentiation, the skeletal system and bone growth, epiphyseal plate, skeletal muscle development, myofilaments, myofibrils, adipose tissue growth and development, lipogenesis and lipolysis.

An outline on myogenesis and the cells involved in myogenesis in farm animals is discussed. This chapter also examines the molecular mechanisms that drive this process in particular on skeletal muscle growth, differentiation and function. Topics include: myogenic cell systems, muscle regulatory factors (MRF), effects of MRF on muscle development, regulation of MRF expression and growth factors affecting muscle growth.

This chapter discusses the important role played by steroid hormones on the growth and development of farm animals. Highlighted topics include: oestrogen and ruminant growth, oestrogen and non ruminants, androgens and ruminant growth, mechanism of action of steroids in ruminant growth and mechanism of action.

A glial fibrillary acidic protein (GFAP) fluorescent enzyme linked immunosorbant assay (ELISA) was compared with an ELISA test kit for GFAP to determine the level of central nervous system (CNS) tissue in advanced meat recovery (AMR) products. The test kit results were highly correlated (r=0.975) with the fluorescent ELISA. Meat cuts and AMR were analyzed on site at 14 meat plants utilizing the test kits. In seven of the plants all AMR samples had less than 1 ng GFAP. Seven of the plants had greater than 1 ng GFAP in AMR samples. Development of proper process controls to eliminate inclusion of spinal cord in AMR materials should bring all values to less than 1 ng GFAP, a level slightly above background.

The current study examined the acute effects of intravenous propionate infusion on plasma hormones and metabolites and the expression of adipose tissue lipogenic genes. Four yearling rams were assigned to one oftwo groups (saline or propionate infusion) in a crossover design. All sheep were cannulated in both jugular veins and infused with 1.2 M propionate at a rate of 64 micromol x mix(-1) x kg BW(-1) for 30 min. Blood samples were collected at -10, 0, 5, 10, 20, 30, 60, and 120 min after initiation of infusion. Subcutaneous adipose tissue biopsies were obtained from the tailhead at 0 and 2 h after propionate infusion and analyzed for gene expressions of lipoprotein lipase, acetyl CoA carboxylase, fatty acid synthase, peroxisome proliferator-activated receptor gamma, leptin, and uncoupling protein-2 using a nonisotopic ribonuclease protection assay. The partial cDNA of the enoyl reductase region of ovine fatty acid synthase was cloned and sequenced from s.c. adipose tissue of sheep. The deduced amino acid sequence (210 amino acids) was 86% identical to human, 88% identical to rat, 88% identical to mouse, and 72% identical to chicken. Plasma glucose and insulin concentrations abruptly increased 5 min after beginning propionate infusion and further increased up until 30 min but were unaffected in saline-infused sheep (P < 0.05). Plasma concentration of NEFA decreased (P < 0.05) during propionate infusion, whereas IGF-I levels were unaltered. The amounts of lipoprotein lipase, acetyl CoA carboxylase, fatty acid synthase, peroxisome proliferator-activated receptor gamma, and leptin mRNA increased (P < 0.05) in s.c. adipose tissue of propionate-infused sheep compared with those of saline-infused sheep. However, uncoupling protein-2 mRNA decreased (P < 0.05) in propionate-infused sheep. This study demonstrates that an acute nutrient challenge, in the form of i.v. propionate, can stimulate or inhibit the expression of various adipose tissue genes involved with lipogenesis and adipose tissue metabolism.

An experiment was conducted to determine the effects of Cu supplementation on performance, subcutaneous adipose tissue mRNA expression of acetyl CoA carboxylase (ACC), stearoyl CoA desaturase (SCD), uncoupling protein 2 (UCP2), and leptin in growing and finishing steers. Forty-eight purebred Angus steers were allotted to one of five treatments: 1) control (no supplemental Cu); 2) 10 mg Cu/kg DM from CuSO4; 3) 10 mg Cu/kg DM from a Cu amino acid complex (Availa Cu); 4) 20 mg Cu/kg DM from CuSO4; 5) 20 mg Cu/kg DM from Availa Cu. Steers were fed an alfalfa hay corn-based diet for 56 d (basal diet contained 7.1 mg Cu/kg DM) and switched to a high-concentrate diet for 144 d (basal diet contained 6.1 mg Cu/kg DM). Blood samples were obtained every 28 d throughout the entire experiment. On d 112 of the finishing period, subcutaneous adipose tissue biopsies were obtained from the tailhead of three animals per treatment and analyzed for ACC, SCD, UCP2, and leptin mRNA expression. Animal performance was not affected by Cu supplementation during the growing phase. Steers receiving 10 mg Cu/kg DM from Availa Cu had higher (P < 0.05) ending body weights and tended (P < 0.10) to have higher ADG than steers receiving 10 mg Cu/kg DM from CuSO4 during the finishing phase. Serum concentrations of nonesterified fatty acid and insulin were not affected by Cu supplementation. Steers receiving supplemental Cu tended (P < 0.11) to have less backfat relative to controls. However, dietary Cu did not influence the level of subcutaneous adipose tissue ACC and SCD mRNA. Neither UCP2 nor leptin gene expression was affected by Cu supplementation. These results indicate that dietary Cu supplementation (10 to 20 mg Cu/kg DM diet) may alter lipid metabolism of subcutaneous adipose tissue; however, it does not seem to affect expression of certain lipogenic genes.