Relative Daily Gain Research Articles

Gain and loss of subcutaneous and abdominal fat depot mass from late pregnancy to 100 days in milk in German Holsteins.

This research paper addresses the hypothesis that in times of negative energy balance around parturition in dairy cattle, lipids stored in adipocytes are mobilised in a more intensive manner out of the abdominal depots than out of the subcutaneous adipose tissues. Furthermore, the impact of niacin supplementation and energy density of the ration on adipose tissue mass gain and loss was assessed. Absolute masses of subcutaneous (SCAT), retroperitoneal (RPAT), omental (OMAT), mesenterial (MAT) and abdominal adipose tissue as a whole (AAT) were estimated by ultrasonography at -42, 3, 21 and 100 DIM. Absolute and relative daily gain during dry period (-42 to 3 DIM) and loss in fresh cow period (3 to 21 DIM) and early lactation period (22 to 100 DIM) were calculated. Feeding regime neither by niacin nor by energy density exerted any effect on adipose tissue masses. The AAT was always bigger than SCAT, but RPAT, OMAT and MAT did not differ amongst each other. All depot masses showed similar patterns with an increase during dry period and a decrease after calving. In fresh cow period AAT absolutely and relatively lost more mass than SCAT. This confirms that AAT is more intensively mobilised than SCAT during that time span. Further absolute daily gain during dry period was strongly negatively correlated with absolute daily loss during fresh cow period. This underlines the impact of individual body condition on adipose mobilisation in periparturient dairy cows. According to these results, it has to be taken into account that the largest amount of fat mobilised in the fresh cow period origins from AAT. This might impact the pattern of adipose derived metabolites and metabolic effectors interacting in physiological and deregulated adaptation to negative energy balance.

Effects of dietary methionine restriction on postnatal growth, insulin sensitivity, and glucose metabolism in intrauterine growth retardation pigs at 49 and 105 d of age.

This study was conducted to investigate the effects of methionine restriction (MR) on growth performance, insulin sensitivity, and hepatic and muscle glucose metabolism in intrauterine growth retardation (IUGR) pigs at 49 and 105 d of age. At weaning (day 21), 30 female normal birth weight (NBW) piglets were fed control diets with adequate methionine (NBW-CON), whereas 60 female IUGR piglets were fed either the control diets (IUGR-CON) or MR diets which were 30% reduced in methionine (IUGR-MR) (n = 6 replicates (pens) with five piglets per replicate). At 49 and 105 d of age, one pig with a BW near to the mean of each replication was selected for biochemical analysis. Compared with NBW-CON pigs, IUGR-CON pigs exhibited lower relative daily gain (RDG) and homeostasis model assessment of insulin resistance (HOMA-IR) index at day 49 (P < 0.05), but higher RDG and HOMA-IR index at day 105 (P < 0.05). Hepatic phosphoenolpyruvate carboxykinase and glucose-6-phosphatase (G6Pase) activities were higher in IUGR-CON than NBW-CON pigs at both days 49 and 105 (P < 0.05), while hepatic glycogen synthase and glycogen phosphorylase activities were lower in IUGR-CON pigs at both two ages (P < 0.05). In addition, compared with NBW-CON pigs, IUGR-CON pigs (105-d old) had lower protein kinase B phosphorylation (PKB/Akt) in liver (P < 0.05), but not in muscle (P > 0.05). Compared with IUGR-CON pigs, IUGR-MR pigs had lower RDG at day 49, less blood glucose at day 105, and lower HOMA-IR index at both days 49 and 105 (P < 0.05). Additionally, compared with IUGR-CON pigs, MR decreased IUGR-MR pigs' hepatic G6Pase activities and increased their hepatic glycogen contents at day 105 (P < 0.05), as well as increased their hepatic and muscle PKB/Akt phosphorylation (P < 0.05). In conclusion, the ability of dietary MR to restrict IUGR pigs' growth and to reduce blood glucose appeared, respectively, in earlier and later period, but MR improved IUGR pigs' insulin sensitivity at both days 49 and 105.

Bayesian analysis of selection for greater weaning weight while maintaining birth weight in beef cattle

An experimental Hereford herd established in 1960 was used from 1986 to 2006 to select for increased weaning weight (W) without increasing birth weight (B). Data were B and W collected over the 47 yr from 2,124 calves. Including ancestors, the pedigree file had 2,369 animals. Selection was practiced only in males. In the first stage (1986 to 1993), mass-selected bulls were chosen with the index I = B + 9374.76 RDG (relative daily gain). From 1994 to 2006, the selection criterion for bull i was I(i) = BLUP(i)(WD) - 2.33 BLUP(i)(BD), where the BLUP were for the direct BV of B (BD) and W (WD), respectively. Predictions were obtained from a 2-trait animal model with B having only BD, and W with WD and WM (maternal additive effects). Selection response was estimated using a Bayesian approach by means of the Gibbs sampler for a 2-trait animal model including BD, BM (maternal BV for B), WD, and WM. Estimated heritabilities for BD, BM, WD, and WM were 0.40, 0.23, 0.05, and 0.23, respectively. The correlation between BD and BM was close to zero (0.01), and between WD and WM was positive (0.37). The correlation between BD and WD was 0.07, and between BM and WM was 0.58. The 2 methods used to estimate selection response gave similar results. In both periods BD decreased, whereas BM increased. The reduction of BD due to selection was slightly larger in the second period than in the first one. The regression of BV for W increased due to selection in both stages, but selection response was 21.6% larger from 1986 to 1992 than from 1993 to 2006. The maternal effect, WM increased more than 3 times compared with WD in the first period, but ended up being almost the same value as WD in period 2. The Bulmer effect was manifested by the decrease in magnitude of all (co)variance components during selection. It is concluded that selection to increase BW at weaning in beef cattle, although not increasing BW at birth, was moderately effective.

Effect of 17α‐Methyltestosterone Treatment and Withdrawal on Growth and Dietary Protein Utilization of Juvenile Rainbow Trout Fed Practical Diets Varying in Protein Level1,2

AbstractThe effects of 17α ‐methyltestosterone (MT) treatment and withdrawal on relative daily gain (RDG), protein gain (PG), productive protein value (PPV), and maximum efficient protein gain (MEPG) of juvenile rainbow trout fed practical diets varying in protein to metabolizable energy (P:ME) ratio were examined over an 18 week period. Two commercially available practical feeds with additions of dextrin and codliver oil were used to formulate diets containing 48% and 32% protein at approximately 320 kcal ME/100 grams with and without 2.0 mg MT/kg of dry diet. MT treated fish were fed hormone supplemented diets for 10 weeks (Phase 1) and hormone free diets for the final eight weeks (Phase 2) of the experiment. Control fish were fed hormone free diets for 18 weeks.MT treatment increased all growth and efficiency factors of fish during Phase 1. The increase in MEPG values due to MT treatment was more pronounced for fish fed the diet containing 48% protein than for fish fed the diet containing 32% protein. Hormone withdrawal reduced growth and efficiency values of fish to below the level of controls during Phase 2. Greater declines occurred for MT treated fish fed the diet containing 32% protein. No difference was observed between final mean RDC, PG, and MEPG values of fish initially fed MT and control fish calculated for the entire 18 weeks. Hormone withdrawal negated MT stimulated increases in empty carcass (EC) fat and whole body (WB) protein and decreases in EC and WB water contents that occurred in Phase 1. EC ash content was increased due to MT treatment and remained high through the period of withdrawal.