J Luo

Growth of Spanish, Boer×Angora and Boer×Spanish goat kids fed milk replacer

Seventy-seven male kids were used to compare growth performance of Spanish (S, n=26), BoerxAngora (BA, n=21) and BoerxSpanish (BS, n=30) kids during the preweaning period. All kids were removed from does 3 days postpartum, moved indoors and randomly allocated to individual cages. Kids received goat milk fortified with milk replacer for approximately 1 week followed by 600ml of milk replacer (23% CP, 30% crude fat) twice daily until weaning at 8 week. At 3 week of age, all kids had ad libitum access to a commercial goat starter diet (20% CP). Feed intake was measured daily and BW gain at 2-week intervals. There were interactions (P<0.05) between breed and time or 2-week period in BW, BW gain and feed efficiency. Boer crosses (i.e., BA and BS) were heavier than S kids at 2, 6 and 8 weeks of age (P<0.05), but there were no BW differences between Boer crosses (P0.10). From Week 3-8, Boer crosses gained BW more rapidly (P=0.001) than did S kids (60, 71 and 77g/day for S, BA and BS, respectively), although BW gain of S in Week 3-4 was greater (P<0.05) than that of Boer crosses (60, 50 and 54g/day for S, BA and BS, respectively). Starter diet DM intake in Week 3-8 was greatest for BS (S versus BA and BS, P=0.05; BA versus BS, P<0.01) (23, 24 and 37g/day for S, BA and BS, respectively). The ratio of BW gain to total DM intake in Week 3-8 was greater (P=0.03) for BA and BS than for S (0.52, 0.59 and 0.58 for S, BA and BS, respectively). The incidence of scours was 17, 21 and 31% for S, BA and BS kids, respectively (P0.10). These results reflect that crossbreeding with Boer goats can improve growth of young kids and, thus, potentially increase economic returns for goat producers.

Cloning, Sequence and Functional Analysis of Goat ATP-binding Cassette Transporter G2 (ABCG2)

ATP-binding cassette transporter G2 (ABCG2) gene encodes a protein that has a wide variety of substrates and is responsible for the active secretion of clinically and toxicologically important molecules into milk. Although known in many species, this marks the first time this gene product has been reported in goats. In this study, we cloned and sequenced goat ABCG2 gene complete coding sequence and predicted its putative translated protein structure with implicative functional domains. One six-transmembrane span on C-terminal region and at least one coiled-coil domain on N-terminal were predicted and compared primarily with those of other closely related species. In addition, three conserved cysteines (in positions 595, 606, and 611) were determined toward the C-terminal of goat’s ABCG2. Two known functional motifs were identified in goat’s protein through comparative studies with other species. The goat ABCG2 relative expression profile revealed that the gene expression was a function of lactation stage and parallel to goat lactation curve.

Relationships Between Body Composition and Shrunk Body Weight and Urea Space in Growing Goats

Abstract Wuliji, T., Goetsch, A.L., Puchala, R., Sahlu, T., Merkel, R.C, Detweiler, G., Soto-Navarro, S., Luo, J. and Shenkoru, T. 2003. Relationships between body composition and shrunk body weight and urea space in growing goats. J. Appl. Anim. Res., 23: 1–24. Growing Spanish wethers and doelings (31; 3.5 mo) consumed ad libitum diets differing in quality continuously for 18 wk or with an increase in quality after 9 wk. Urea space (US), shrunk body weight (SBW) and chemical composition of the whole body were determined at the beginning, middle and end of the experiment. In addition, at the beginning of the experiment the same determinations were made with two yearling Boer × Spanish doelings that had consumed a high quality diet ad libitum for 12 wk. Mean, standard error, minimum and maximum values were 20.4, 1.14, 10.3 and 42.0 kg SBW; 64.0, 1.05, 47.2 and 72.3% water; 15.7, 1.19, 6.0 and 32.3% fat and 17.3, 0.25, 14.0 and 20.9% protein. Regressions of water, fat and protein concentrations and masses against US and (or) SBW were performed. Model fit was assessed by R2, root mean square error (RMSE) and the distribution of residuals (observed—predicted) among predicted values. Overall, SBW explained considerably more variability in body composition than did US, although US slightly improved predictions of water and fat masses and concentrations. Equations explaining greatest variability with acceptable distributions of residuals were: water, kg = 1.274 (SE = 1.1608) + (0.1546 (SE = 0.05863) × US, kg) + (0.5782 (SE = 0.10861) × SBW, kg)—(0.0043 (SE = 0.00205) × SBW2, kg) [n = 33; R2 = 0.944; adjusted R2 = 0.938; RMSE = 2.266]; fat, kg = −0.921 (SE = 1.1389)—(0.1520 (SE = 0.05753) × US, kg) + (0.1564 (SE = 0.10656) × SBW, kg) + (0.0064 (SE = 0.00201) × SBW2, kg) [n = 33; R2 = 0.942; adjusted R2 = 0.936; RMSE = 0.734]; and protein,% water = 34.696 (SE = 3.9913)—(0.1175 (SE = 0.06192) × predicted water,%) [n = 33; R2 = 0.101; adjusted R2 = 0.073; RMSE = 1.983]. In conclusion, such equations may have utility for within experiment treatment comparisons or for assessing changes in composition. However, validation with an independent animal population is desirable as well as is future research with larger numbers of animals, different types of goats and procedural considerations.

Fatty acid elongase 5 (ELOVL5) alters the synthesis of long-chain unsaturated fatty acids in goat mammary epithelial cells

Increased production of long-chain unsaturated fatty acids (LCUFA) can have a positive effect on the nutritional value of ruminant milk for human consumption. In nonruminant species, fatty acid elongase 5 (ELOVL5) is a key enzyme for endogenous synthesis of long-chain unsaturated fatty acids. However, whether ELOVL5 protein plays a role (if any) in ruminant mammary tissue remains unclear. In the present study, we assessed the mRNA abundance of ELOVL5 at 3 stages of lactation in goat mammary tissue. Results revealed that ELOVL5 had the lowest expression at peak lactation compared with the nonlactating and late-lactating periods. The ELOVL5 was overexpressed or knocked down to assess its role in goat mammary epithelial cells. Results revealed that ELOVL5 overexpression increased the expression of perilipin2 (PLIN2) and decreased diacylglycerolacyltransferase 2 (DGAT2) and fatty acid desaturase 2 (FADS2) mRNA, but had no effect on the expression of DGAT1, FADS1, and stearoyl-CoA desaturase 1 (SCD1). Overexpression of ELOVL5 decreased the concentration of C16:1n-7, whereas no significant change in C18:1n-7 and C18:1n-9 was observed. Knockdown of ELOVL5 decreased the expression of PLIN2 but had no effect on DGAT1, DGAT2, FADS1, FADS2, and SCD1 mRNA expression. Knockdown of ELOVL5 increased the concentration of C16:1n-7 and decreased that of C18:1n-7. The alterations of expression of genes related to lipid metabolism after overexpression or knockdown of ELOVL5 suggested a negative feedback regulation by the products of ELOVL5 activation. However, the content of triacylglycerol was not altered by knockdown or overexpression of ELOVL5 in goat mammary epithelial cells, which might have been due to the insufficient availability of substrate in vitro. Collectively, these are the first in vitro results highlighting an important role of ELOVL5 in the elongation of 16-carbon to 18-carbon unsaturated fatty acids in ruminant mammary cells.

Serotonin induces parathyroid hormone-related protein in goat mammary gland

During lactation, large amounts of calcium are exported from the mammary gland into milk to ensure skeletal growth of the offspring. Recent studies revealed that serotonin (5-HT) is essential to stimulate skeletal calcium resorption for milk synthesis. Our objective was to explore the correlation between circulating 5-HT and serum calcium and parathyroid hormone-related protein (PTHrP) concentrations around parturition in dairy goats. We also investigated the effect of 5-HT on PTHrP expression in cultured primary goat mammary epithelial cells (GMEC). Blood samples of multiparous Guanzhong dairy goats were collected on day -5 to 3 postpartum for analysis of serum concentrations of calcium, 5-HT, and PTHrP. Results revealed that from day -3 to 0 postpartum serum calcium and 5-HT concentrations decreased progressively, but serum PTHrP concentration only had a sharp drop in the postpartum period sampled. Correlation analysis of circulating 5-HT and serum calcium and PTHrP concentrations on day 1 and 2 postpartum revealed that low serum 5-HT concentration was positively correlated with serum total calcium or PTHrP concentration. By knocking down tryptophan hydroxylase-1 (TPH1) or adding 5-hydroxytryptophan (5-HTP) to decrease or increase the levels of 5-HT in GMEC, we observed that 5-HTP increased PTHrP expression in a dose-dependent manner and siTPH1 decreased PTHrP protein expression. Furthermore, 5-HT increased mRNA abundance of calcium-sensing receptor (CaSR) in a dose-dependent manner and decreased the expression of plasma membrane Ca2+ ATPase-1 (PMCA1). Taken together, 5-HT seems to induce PTHrP expression in goat mammary cells during and after parturition. These findings suggest that increasing 5-HT biosynthesis could be a potential therapeutic target for prevention of hypocalcemia in dairy goats.