Net Energy For Growth Research Articles

Potassium and Manganese Fertilization and the Effects on Millet Seed Yield, Seed Quality, and Forage Potential of Residual Stalks

Millets are important natural grain source for wild and game birds and the domesticated varieties are good sources of grain for human and livestock nutrition as well as summer forage. Unlike sorghum, millet seed has less anti-nutrient factors and is a better choice for animal feed formulations. Pearl millet is an example of such millets and has both forage- and grain-type varieties. However, opportunities exist for dual use of millet for grain and residue for forage. In this study two millets: Pennisetum glaucum (L.) R. Br. (Pearl millet var. TifGrain 102) and Panicum ramosum (L.) (Browntop millet) were evaluated for their response to potassium (K) and manganese (Mn) fertilizer. The experiment was a randomized complete block with treatments in a split-split arrangement. Potassium and Mn were supplied as K fertilizer (0-0-60) and manganese sulfate (MnSO4·2H2O), respectively. Potassium and Mn fertilizer rates and their interaction with each other and variety had no effect on determined parameters. TifGrain 102 grain yield averaged at 5900 kg·ha-1 was significantly greater than 4680 kg·ha-1 obtained for Browntop millet. While grain oil contents were similar, Browntop grain had greater contents of crude proteins. And except for K, Browntop seed had greater contents of all determined macro-and micronutrients. Residual stalks of Browntop had greater forage crude protein, total digestible nutrient (TDN) and lower acid detergent fiber (ADF). Browntop residual material had greater quantities of estimated net energy for growth (NEG), lactation (NEL), maintenance (NME). While TifGrain 102 residual stalks had greater contents of P and K, it had significantly lower contents of Ca, Mg and S compared to Browntop. Overall, while these two millets have shown good potential for dual use, Browntop may offer a better choice for high quality seed and residual stalks for forage.

Effects of dietary supplementation of rumen-protected folic acid on rumen fermentation, degradability and excretion of urinary purine derivatives in growing steers

ABSTRACTThe present experiment was undertaken to determine the effects of dietary addition of rumen-protected folic acid (RPFA) on ruminal fermentation, nutrient degradability, enzyme activity and the relative quantity of ruminal cellulolytic bacteria in growing beef steers. Eight rumen-cannulated Jinnan beef steers averaging 2.5 years of age and 419 ± 1.9 kg body weight were used in a replicated 4 × 4 Latin square design. The four treatments comprised supplementation levels of 0 (Control), 70, 140 and 210 mg RPFA/kg dietary dry matter (DM). On DM basis, the ration consisted of 50% corn silage, 47% concentrate and 3% soybean oil. The DM intake (averaged 8.5 kg/d) was restricted to 95% of ad libitum intake. The intake of DM, crude protein (CP) and net energy for growth was not affected by treatments. In contrast, increasing RPFA supplementation increased average daily gain and the concentration of total volatile fatty acid and reduced ruminal pH linearly. Furthermore, increasing RPFA supplementation enhanced the acetate to propionate ratio and reduced the ruminal ammonia N content linearly. The ruminal effective degradability of neutral detergent fibre from corn silage and CP from concentrate improved linearly and was highest for the highest supplementation levels. The activities of cellobiase, xylanase, pectinase and α-amylase linearly increased, but carboxymethyl-cellulase and protease were not affected by the addition of RPFA. The relative quantities of Butyrivibrio fibrisolvens, Ruminococcus albus, Ruminococcus flavefaciens and Fibrobacter succinogenes increased linearly. With increasing RPFA supplementation levels, the excretion of urinary purine derivatives was also increased linearly. The present results indicated that the supplementation of RPFA improved ruminal fermentation, nutrient degradability, activities of microbial enzymes and the relative quantity of the ruminal cellulolytic bacteria in a dose-dependent manner. According to the conditions of this experiment, the optimum supplementation level of RPFA was 140 mg/kg DM.

Energy requirements for the maintenance and growth of Dorper-Jinzhong crossbred ram lambs

The sheep industry in China has been rapidly developing in recent years; however, the animals’ nutritional requirements under certain conditions have not been thoroughly defined. The objective of this study was to investigate the energy requirements of both the maintenance and growth of Dorper-Jinzhong crossbred ram lambs. Thirty 1/2 Dorper × 1/2 Jinzhong crossed F1 ram lambs (35 ± 0.5 kg of body weight, BW) were randomly selected and divided into five groups in a randomised design for a comparative slaughter trial. The lambs were offered one type of feed at 100%, 65% and 40% of the ad libitum intake. Another 15 lambs were used for the digestibility trial to estimate the metabolisable energy (ME) values of the diet at various feed intake levels. The net energy for maintenance (NEm) and the ME requirement for maintenance (MEm) were 286.68 kJ/kg0.75 of SBW and 437.80 kJ/kg0.75 of SBW, respectively; the energy efficiency for maintenance (km) was 0.655. The net energy for growth (NEg) values for varying average daily gain (100–350 g) in ram lambs grown from 35 to 50 kg increased from 1.31 to 5.93 MJ/d with an energy efficiency for growth (kg) of 0.457. Our results suggest that the energy requirements of Dorper-Jinzhong crossbred ram lambs are lower than the requirements recommended by the National Research Council (NRC) and Agricultural and Food Research Council (AFRC).

Energy requirements for maintenance and growth of male saanen goat kids.

The aim of study was to determine the energy requirements for maintenance and growth of forty-one Saanen, intact male kids with initial body weight (BW) of 5.12±0.19 kg. The baseline (BL) group consisted of eight kids averaging 5.46±0.18 kg BW. An intermediate group consisted of six kids, fed for ad libitum intake, that were slaughtered when they reached an average BW of 12.9±0.29 kg. The remaining kids (n = 27) were randomly allocated into nine slaughter groups (blocks) of three animals distributed among three amounts of dry matter intake (DMI; ad libitum and restricted to 70% or 40% of ad libitum intake). Animals in a group were slaughtered when the ad libitum-treatment kid in the group reached 20 kg BW. In a digestibility trial, 21 kids (same animals of the comparative slaughter) were housed in metabolic cages and used in a completely randomized design to evaluate the energetic value of the diet at different feed intake levels. The net energy for maintenance (NEm) was 417 kJ/kg0.75 of empty BW (EBW)/d, while the metabolizable energy for maintenance (MEm) was 657 kJ/kg0.75 of EBW/d. The efficiency of ME use for NE maintenance (km) was 0.64. Body fat content varied from 59.91 to 92.02 g/kg of EBW while body energy content varied from 6.37 to 7.76 MJ/kg of EBW, respectively, for 5 and 20 kg of EBW. The net energy for growth (NEg) ranged from 7.4 to 9.0 MJ/kg of empty weight gain by day at 5 and 20 kg BW, respectively. This study indicated that the energy requirements in goats were lower than previously published requirements for growing dairy goats.

The effects of dietary L-carnitine and rumen-protected choline on growth performance, carcass characteristics and blood and rumen metabolites of Holstein Young bulls

An experiment was conducted to determine the effects of L-carnitine (LC) and rumen-protected choline (RPC) on growth performance, carcass characteristics and blood and rumen metabolites of finishing bulls. Twenty-eight Holstein young bulls (average initial weigh 310±24 kg) were used in a completely randomized design with four treatments and seven replicates with 2×2 factorial arrangement for 90 days. Basal diets were formulated for 14% crude protein and 1.14 Mcal/kg of net energy for growth and contained 24% of dietary dry matter (DM) as corn silage, 6.8% alfalfa hay, 46.50% barley grain and 9.5% canola meal. Treatments included: (1) without LC and RPC or control; (2) 4g/d LC head−1; (3) 5 g/d RPC head-1; (4) 4 g/d LC head−1 and 5 g/d RPC head−1. Calves were fed ad libitum and had free access to fresh water. There were no differences between diets for DM intake, average daily gain and gain:feed. Plasma concentrations of glucose, insulin, nonesterified fatty acid, β-hydroxybutyrate, cholestrol and aspartate aminotransferase were not affected by treatments, but plasma triglyceride concentration decreased in calves fed RPC (P < 0.05). Longissimus muscle area, pelvic, kidney, heart and rumen and intestine fats were not affected by treatments. Subcutaneous fat and backfat thickness decreased in calves fed RPC (P < 0.05). LC and RPC had no significant effects on chemical composition of meat and liver (protein, fat, ash and dry mater). There was no significant difference between diets for rumen liquor volatile fatty acid and pH. This study showed that LC and RPC supplements cannot affect growth performance in Holstein young bulls, but lipid metabolism may be affected by LC and RPC.

Nutritive value of red clover and lucerne forages for ruminants estimated by in vitro and in vivo digestibility methods

The aim of this study was to determine the nutrient and energy levels of red clover and lucerne forage. Investigation of forage at different maturity stages of three growths was carried out by chemical analysis, in vitro and in vivo digestibility methods.&amp;nbsp; Generally, maturation caused a significant increase in fibre fractions. With the increasing maturity of forage samples the in vivo, in vitro, and calculated in vivo (in vivo&lt;sub&gt;calcul&lt;/sub&gt;) digestibilities of organic matter (OM) linearly decreased. The in vitro and in vivo&lt;sub&gt;calcul&lt;/sub&gt; digestibilities of OM averaged 0.754 and 0.708 for red clover and 0.717 and 0.667 for lucerne, respectively. The in vivo OM digestibility averaged 0.710 for red clover and 0.666 for lucerne. Gross energy (GE), digestible energy (DE), metabolizable energy (ME), net energy for lactation (NEL), and net energy for growth (NEG) averaged 18.12, 12.41, 9.60, 5.67, 5.50 and 18.09, 11.56, 9.01, 5.26, 4.99 MJ/kg of dry matter for red clover and lucerne, respectively. The effect of a vegetative stage on energy values of both forages was diverged for various growth times. When data were pooled across the estimated season, seven cutting-specific equations for descriptions of GE, DE, ME, NEL, NEG, in vitro, and in vivo OM digestibilities were obtained for red clover and lucerne, separately. The red clover model expression gave similar prediction equations for lucerne. It was possible to predict cutting-specific equations with coefficients of determination R&lt;sup&gt;2&lt;/sup&gt; &amp;gt; 0.719 for red clover and R&lt;sup&gt;2&lt;/sup&gt; &amp;gt; 0.400 for lucerne of the variation in GE, DE, ME, NEL, and NEG. The in vitro and in vivo OM digestibility equations were predicted with R&lt;sup&gt;2 &lt;/sup&gt;being 0.840 (in vitro) and 0.707 (in vivo) for red clover, and 0.979 (in vitro) and 0.937 (in vivo) for lucerne. The parameters of these specific equations were statistically preferable than the general model expression which included both forages together. &amp;nbsp;

Effects of grazing on deposition of chemical body components, energy retention and plasma hormones in steers

The objective of this study was to evaluate the effects of grazing on the accretion of energy and chemical components in steers, using the comparative slaughter technique and taking into consideration the growth rate. Twelve Holstein steers aged 6 months and weighing 160 kg were divided into three treatment groups – an initial, grazing and control group. The initial group was slaughtered at the beginning of the experiment. The grazing group was grazed on timothy pastures for 18 weeks. The control group was kept in a stable and offered concentrate and timothy hay in a proportion of 2:1 throughout the 18 weeks. The amount of ration offered to the control group was adjusted in order to obtain a growth rate similar to that of the grazing group. The grazing and control groups were slaughtered at the end of the experiment. The grazing and the control groups had similar growth rates of approximately 0.8 kg/day throughout the experimental period and similar final live weights of approximately 260 kg. The grazing group had lower fat and energy deposition rates than the control group (P < 0.05). Deposition rates of protein, fat, ash, moisture and energy were 130, 32, 30, 374 g/day and 4.4 MJ/day, respectively, in the grazing group and 117, 85, 32, 381 g/day and 6.2 MJ/day, respectively, in the control group. The net energy for growth was lower in the grazing group (7.7 MJ/kg) than in the control group (9.9 MJ/kg, P < 0.05). The grazing group had higher plasma concentrations in growth hormone and lower plasma concentrations in insulin and insulin-like growth factor 1 than those in the control group (P < 0.05).

Interfacing Large Interactive Systems Models and the User: The Case of a Beef Cattle Enterprise Model for Decision Assistance

The interface between a large interactive simulation model and the user is discussed along with and in the context of a general beef cattle enterprise model designed to be used as a decision assistance tool. Emphasis in this model is on the cow/calf land extensive form of operation. A highly disaggregated herd population model allows full exploration of population dynamics. Using total digestible nutrients (TDN) as the basic feed quality description, and net energy for growth and maintenance where possible, the nutrient impact component predicts rates of weight gain and reproductive dynamics as a function of feed intake. Forage growth is modeled as a function of the exogenous variables of solar radiation, temperature, and rainfall. As an enterprise model, attention is focused on the planning and management decisionmaking needs of decisionmakers. The model is viewed as a tool for exploration of alternative strategies to assist the traditional and intuitive method of management. The model is interactive, with straightforward decisions made using endogenous decision rules, while complex decisions require the input of the model user. The design of the interface between the model and the user to allow effective interaction is discussed in detail. A demonstration of the model's capability is given using a project investment planning example.