Prediction of utilizable true protein of mixed rations for sheep using an in vitro incubation technique

The objective of the present experiment was to study the relationship between in vitro utilizable true protein (uTP) and in vivo-uTP of sheep rations by regression analysis. A further aim was to analyse if in vivo-uTP of mixed rations could be predicted by regression analysis between in vitro-uTP and in vivo-uTP, using N-retention of sheep as important evaluation criteria of protein value. Three adult male sheep (body weight [BW] 46 + 1.3 kg) fitted with rumen cannulas and simple T-type duodenal cannulas were fed with twelve typical rations with graded levels of crude protein and true protein in four experiments according a 3 x 3 Latin square design. Each experimental period included an adaptation (7 days), a N balance trial (4 days) and a collection of duodenal digesta (3 days). During collection of duodenal digesta, polyethylene glycol and chromium oxide were used as dual markers for the measurement of duodenal digesta flow and calculation of the in vivo-uTP of duodenal digesta. The in vitro-uTP of the rations was determined using the in vitro incubation technique of Zhao and Lebzien (2000). It was found that both in vitro-uTP intake and in vivo-uTP intake were significantly correlated with N-retention (p < 0.001) and that there was a significant linear relationship between the content of in vitro-uTP and in vivo-uTP in rations (p < 0.001). Therefore, it was concluded that the used in vitro incubation technique is suitable for the determination of in vitro-uTP of mixed rations for sheep, and that the amount of in vivo-uTP can be predicted by regression between in vitro-uTP and in vivo-uTP.     

Cornell Net Carbohydrate and Protein System: A model for precision feeding of dairy cattle

The Cornell Net Carbohydrate and Protein System (CNCPS) predicts cattle requirements and nutrient supply for site-specific situations. This paper describes the CNCPS version 6 (CNCPSv6), which represents a re-engineering and updating of CNCPS version 5 with the following objectives: (1) improve the organization of the model and user interface to improve speed and accuracy in formulating diets for a herd of dairy cattle, (2) expand the carbohydrate pools to include sugars, soluble fibers, and organic and volatile fatty acids, (3) integrate a fat model to account for ruminal lypolization and biohydrogenation, and absorption of fatty acids in the small intestine, and (4) update the computational sub-models with new information. The CNCPSv6 model was re-designed using object-oriented programming in which physiological functions (e.g. growth, lactation, pregnancy) and anatomical compartments (e.g. rumen, intestines) were programmed as objects. The interface uses farm, location, and group flow, which decreases the number of inputs required per cattle group and allows for more rapid evaluation of diets, feed requirements, and nutrient excretion by location, group, and herd. The revised implementation of the body reserves sub-model allows accounting for fluxes in energy reserves when formulating diets. Updated equations and coefficients include the prediction of rumen ammonia balance and feed passage rates, indigestible DM, MP lactation efficiency, and DMI. The CNCPSv6 was evaluated with data from individually fed lactating dairy cows from three independent studies. As implemented, CNCPSv6 accounted for a similar proportion of the variation (86%) in first limiting (ME or MP) milk production as CNCPSv5 but with a lower bias (1% versus 4%, respectively). We concluded the re-designing and updating of the CNCPS improved its ability to formulate and evaluate a feeding program for a herd of dairy cattle with greater accuracy and efficiency.     

Substitution of crude cell wall for neutral detergent fibre in the equations of the Cornell Net Carbohydrate and Protein System that predict carbohydrate fractions: application to sunflower ( Helianthus annuus L.)

Prediction of carbohydrate fractions using equations from the Cornell Net Carbohydrate and Protein System (CNCPS) is a valuable tool to assess the nutritional value of forages. In this paper, these carbohydrate fractions were predicted using data from three sunflower (Helianthus annuus L.) cultivars, fresh or as silage. The CNCPS equations for fractions B2 and C include measurement of ash and protein-free neutral detergent fibre (NDF) as one of their components. However, NDF lacks pectin and other non-starch polysaccharides that are found in the cell wall (CW) matrix, so this work compared the use of a crude CW preparation instead of NDF in the CNCPS equations. There were no differences in the estimates of fractions B1 and C when CW replaced NDF; however, there were differences in fractions A and B2. Some of the CNCPS equations could be simplified when using CW instead of NDF. Notably, lignin could be expressed as a proportion of DM, rather than on the basis of ash and protein-free NDF, when predicting CNCPS fraction C. The CNCPS fraction B1 (starch + pectin) values were lower than pectin determined through wet chemistry. This finding, along with the results obtained by the substitution of CW for NDF in the CNCPS equations, suggests that pectin was not part of fraction B1 but present in fraction A. We suggest that pectin and other non-starch polysaccharides that are dissolved by the neutral detergent solution be allocated to a specific fraction (B2) and that another fraction (B3) be adopted for the digestible cell wall carbohydrates.     

Evaluation of dry matter intake and daily weight gain predictions of the Cornell Net Carbohydrate and Protein System with local breeds of beef cattle in China

Three feeding trials with different dietary treatments were conducted to evaluate predictions of dry matter intake and average daily gain of Chinese local beef cattle by Cornell Net Carbohydrate and Protein System (CNCPS) version 5.0. In Trial 1, 60 growing Jin Nan yellow steers (local yellow cattle breed originated from Shanxi Province) were assigned to two treatments with five pens in each treatment and six animals in each pen. Trial 2 was conducted with 72 Lu Xi yellow growing steers (local yellow cattle breed originated from Shandong Province) in 12 conventional pens. These animals were assigned to four treatments with six animals in each pen. In Trial 3, 60 Lu Xi yellow steers were allocated to four treatments with five animals in each pen. Average daily dry matter intake (DMI) for each steer was measured as a mean of each pen. All the data about animals, environment, management and feeds required by the CNCPS model were collected, and model predictions were generated for animals of each pen. Model predictions were evaluated by mean bias, mean square prediction error (MSPE) and regression between the observed and predicted values. Animals in 9 of 10 treatments showed a very close model-predicted DMI values to the observed. In another treatment, animals had a mean bias of −0.72 kg DM/day (TRT 10 in Trial 3). With overall data included, the regression equation between observed and predicted DMI was: Y_OBS = 1.10X_CNCPS − 0.78 (R² = 0.82; P<0.0001), with an intercept not different (P=0.32) from zero, but a slope still different (P<0.0001) from 1. Although the model-predicted ADG values were very close to the observed values in all trials, most of the predicted values were always lower than the observed values with absolute mean bias less than 0.2. When all data were pooled, the regression equation between observed and predicted ADG was: Y_OBS = 1.07X_CNCPS + 0.02 (R² = 0.73; P<0.0001), with an intercept not different from zero (P=0.88), but a slope that differed from unity (P<0.0001). Results suggest that the CNCPS model is an acceptable model to predict dietary DM intake and average daily gain of Chinese local beef cattle breeds. Further studies are warranted to introduce model adjustment for Chinese conditions.     

The suitability of a faecal suspension of sheep as inocula for the estimation of utilizable crude protein of feeds by in vitro incubation

The objective of this review is to outline those parts of modelling approaches in pig production which are not highly developed; these are the partitioning of protein and lipid accretion in different anatomical body parts. The authors introduce present models with a critical evaluation and draw some conlusions for further developments. Based on present knowledge this paper demonstrates the process of protein and fat accretion in different body compartments in pigs and influencing factors. A further aim is to assist in the conceptual development of a new pig model, which is more detailed, precise and accurate than currently available models. Exsisting models are generally deficient with regard to the translation of lipid and protein gain into lean and fatty tissue. Only assumed values for this translation have been used so far and the concepts underlying these values are not well understood. Therefore, it may be appropriate to develop a compartimental model to predict protein and fat deposition in growing and fattening pigs. With this new approach the model can supply sufficiently the changing consumer demands regarding to the possibility of meat quality prediction.     

The suitability of a faecal suspension of sheep as inocula for the estimation of utilizable crude protein of feeds by in vitro incubation

The objective of the experiments was to study the suitability of using a faecal suspension of sheep for the estimation of the utilizable crude protein (uCP) of feeds for sheep by an in vitro incubation. Twenty-four single feeds and eight feed mixtures were used as incubation substrates. In Experiment 1, the gas production after the in vitro incubation with rumen fluid or with a faecal suspension of a sheep were compared using the Hohenheim gas test. It was found that there were significant linear regression between the 24, 48 and 72 h gas production with rumen fluid and those with faecal suspensions of 35, 50, 100 and 150 g wet faeces of sheep (which were 18.6, 23.5, 52.0 and 70.5 g faeces DM, respectively) per litre McDougall's buffer (P < 0.0001). The highest regression coefficient (r2) was calculated between the gas production after inoculation with a suspension of 100 g wet faeces per litre McDougall's buffer (x, ml x 200 mg (-1) feed DM) for 48 h and the gas production after inoculation with rumen fluid (y, ml x 200 mg (-1) feed DM) for 24 h: y = 0.82 (+/- 0.07)x + 9.87 (+/-3.83), r2 = 0.82, n = 32, P < 0.0001. Based on these results, in Experiment 2 the estimation of utilizable crude protein (uCP) of feeds was compared by using the in vitro incubation technique of Zhao and Lebzien (2000), where feeds were inoculated either with rumen fluid or with a faecal suspension (100 g wet faeces of sheep, i.e. 52 g faeces DM per litre McDougall's buffer). The results indicated that there were no significant differences of the estimated uCP after inoculation with rumen fluid or the faecal suspension (P > 0.05). A significant regression was found between the uCP after incubation for 48 h with 100 g wet faeces (x, g x kg (-1) DM) and the uCP after incubation for 24 h with rumen fluid (y, g x kg(-1) DM): y = 0.95 (+/-0.10)x - 4.90 (+/-26.70), r2 = 0.75, n = 32, Although this regression was significant, the coefficient r2 was not high. Therefore, further research is needed before sheep faeces could replace rumen fluid as an inocula for the estimation of uCP by the in vitro incubation technique.     

Characterization of a Sulfoglucuronyl Carbohydrate Binding Protein in the Developing Nervous System

Abstract: The developmentally regulated and stage-specifically expressed HNK-1 carbohydrate found on sulfoglucuronylglycolipids (SGGLs) and certain glycoproteins has been proposed to be involved in neural cell adhesion and recognition processes through its interaction with protein "receptors." We have isolated and purified a ∼30-kDa SGGL-binding protein (SBP-1) from neonatal rat brain. SBP-1 specifically bound to SGGLs and sulfatide both in solid-phase immunobinding and high-performance thin-layer chromatography-immunooverlay assays. N-terminal sequence analysis showed that SBP-1 is similar to an adhesive neurite outgrowth promoting protein amphoterin. Desulfation of SGGLs resulted in abolition of SBP-1 binding. However, chemical modification of glucuronic acid moiety by either esterification or reduction of the carboxyl group had no effect, suggesting requirement of the carbohydrate-linked sulfate group for SBP-1 binding. The binding of SBP-1 to SGGLs was specifically inhibited by HNK-1 antibody but not by other IgM antibodies. The binding of SBP-1 to sulfatide, however, was not inhibited by HNK-1 antibody. Heparin, fucoidan, and dextran sulfate (50K) also inhibited the binding of SBP-1 to SGGLs. During development of the rat cerebral cortex, the level of SBP-1 decreased after embryonic day 18 to an almost undetectable level by postnatal day 10; whereas in the cerebellum, the expression of SBP-1 was maximal at postnatal day 7. SBP-1 also bound specifically to the HNK-1 glycoproteins isolated from rat brain by HNK-1 immunoaffinity chromatography. Proteins without HNK-1 carbohydrate did not bind SBP-1. The binding to HNK-1 glycoproteins was inhibited by HNK-1 antibody, but not by other IgM antibodies, indicating that the binding was mediated through the HNK-1 carbohydrate moiety of the proteins. The interaction and coexpression of SBP-1 with SGGLs and HNK-1 glycoproteins, during the perinatal brain development, suggest a functional role for this protein.     

Incorporation of intraportal ammonia-N into blood and tissue nitrogenous compounds in chickens fed low and high protein diets

1. 15N-Percentage of the amide of glutamine in total blood non-protein-15N was 42 and 48% in chickens fed 5 and 20% protein diets, respectively, when 15N-ammonia was intraportally-infused for 6 hr. 2. The infused ammonia-15N also appeared in the amide of free glutamine in the liver and kidney in large amounts at both levels of protein intake. 3. The 15N incorporated into glutamine-amide in the blood, liver and kidney and non-protein-15N in plasma were greater in chickens fed the low protein diet than in those fed the high protein diet (P less than 0.05 except kidney of P less than 0.01). 4. About 60% of the amide-N of the glutamine which was increased during 6 hr infusion of ammonia was derived from infused ammonia-N and the remainder from endogenous nitrogen, irrespective of protein intake. 5. These results suggest that glutamine is the most important intermediate in detoxication of intraportal ammonia in chickens.     

Development of an in vitro incubation technique for the estimation of the utilizable crude protein (uCP) in feeds for cattle

An in vitro incubation technique based on the first stage of the in vitro digestion technique published by Tilley and Terry (1963) was developed to estimate the utilizable crude protein (uCP) of single feeds and feed mixtures as non ammonia‐N after 24 h of incubation. The results of 25 feed samples showed that there was a significant relationship between the uCP values calculated by regression based on in vivo data sets (Y, CP [g‐kg^‐1 DM]) and those measured by the in vitro incubation technique (X, CP [g‐kg^‐1 DM], 24 h incubation):

y=0.85x+18.0, r²=0.84, P≤0.001.

It was concluded that it can be possible to determine the uCP value of single feeds or feed mixtures by this in vitro incubation technique and to estimate the uCP value of feeds by this regression equation.     

Using mixed silages of sweet sorghum and alfalfa in total mixed rations to improve growth performance,nutrient digestibility,carcass traits and meat quality of sheep

Combining sweet sorghum (SS) with alfalfa for ensiling has the potential to make a high-quality silage with relatively a better nutrient balance. However, the existing data are insufficient about how changes in ratios of SS to alfalfa in different silage mixtures affect animal performance and meat quality. Therefore, the objective of this study was to determine the effect of feeding total mixed rations containing mixed silages of SS and alfalfa on growth performance, nutrient digestibility, carcass traits and meat quality of Karakul sheep. Five total mixed rations were formulated with different SS proportions at 100%, 80%, 60%, 40%, and 20% on a fresh weight basis. Thirty 4-month old male Karakul sheep with 25.5 ± 1.4 kg BW were randomly allocated into five treatment groups, each with six lambs for this experiment. The results indicated that the Karakul sheep consuming total mixed rations containing SS-Alfalfa (SS-AF) silage mixtures with a lower proportion of SS tended to increase nutrient digestibility, growth performance, carcass traits, and meat quality. Feeding diets with SS at 40% and 20% inclusion rate showed a significant linear increase in the apparent digestibility of DM, CP and NDF, as well as subcutaneous fat thickness and water holding capacity (P < 0.5). Moreover, reduction in SS inclusion rate in these diets caused significant (P < 0.05) linear and quadratic increases in DM intake, final BW, average daily gain, carcass weight, and the amino acid contents of meat (P < 0.05). Conversely, feeding diet with lower SS inclusion rate led to decrease in feed conversion ratio and shear force significantly (P < 0.05) for these sheep. It appears that 40% inclusion of SS was the optimal rate in making the SS-AF silage mixture for lambs to achieve a superior production performance and high-quality meat products in Karakul sheep. However, further research is needed to investigate the effect of feeding SS-AF silage mixtures alongside contrasting ingredients on rumen function, ruminal microorganisms and digestive enzyme activity of sheep and other ruminant animals.     

Prediction of total fecal output in sheep fed silage using the Captec chrome controlled-release capsule

Six Finnish wethers (average weight, 52.3 kg) were used to determine the effectiveness of a controlled-release Cr₂O₃ bolus and the internal marker acid insoluble ash (AIA) for predicting fecal output. Wethers were fed grass silage for ad libitum intake. Each wether was dosed orally with one continuous-release Cr₂O₃ bolus (CRC) on the first day of the experiment. Chronology of the trial was as follows: Day 0 to 14, marker adaptation period; Day 15 to 21, total fecal collection; Day 22 to 23, fecal grab sampling every 4 h; Day 25 to 35, once-daily fecal grab sampling. Accuracy of marker-estimated fecal output derived from each method was compared within a marker with total fecal collection values using a paired t-test. Concentrations of AIA and Cr varied (P < 0.10) between sampling times. Accuracy of fecal output estimates was better with the controlled-release Cr₂O₃ bolus (r = 0.97; P = 0.03) than with AIA (r = −0.08; P = 0.89). Grab samples taken once produced reliable (r = 0.96; P = 0.02) estimates of fecal output of silage-fed wethers using the controlled-release Cr₂O₃ bolus. The controlled-release Cr₂O₃ bolus is a better marker than acid-insoluble ash for predicting fecal output of silage-fed wethers.     

Resistance training alters the response of fed state mixed muscle protein synthesis in young men

Ten healthy young men (21.0 +/- 1.5 yr, 1.79 +/- 0.1 m, 82.7 +/- 14.7 kg, means +/- SD) participated in 8 wk of intense unilateral resistance training (knee extension exercise) such that one leg was trained (T) and the other acted as an untrained (UT) control. After the 8 wk of unilateral training, infusions of L-[ring-d(5)]phenylalanine, L-[ring-(13)C(6)]phenylalanine, and d(3)-alpha-ketoisocaproic acid were used to measure mixed muscle protein synthesis in the T and UT legs by the direct incorporation method [fractional synthetic rate (FSR)]. Protein synthesis was determined at rest as well as 4 h and 28 h after an acute bout of resistance exercise performed at the same intensity relative to the gain in single repetition maximum before and after training. Training increased mean muscle fiber cross-sectional area only in the T leg (type I: 16 +/- 10%; type II: 20 +/- 19%, P < 0.05). Acute resistance exercise increased muscle protein FSR in both legs at 4 h (T: 162 +/- 76%; UT: 108 +/- 62%, P < 0.01 vs. rest) with the increase in the T leg being significantly higher than in the UT leg at this time (P < 0.01). At 28 h postexercise, FSR in the T leg had returned to resting levels; however, the rate of protein synthesis in the UT leg remained elevated above resting (70 +/- 49%, P < 0.01). We conclude that resistance training attenuates the protein synthetic response to acute resistance exercise, despite higher initial increases in FSR, by shortening the duration for which protein synthesis is elevated.     

REML estimation of variance parameters in nonlinear mixed effects models using the SAEM algorithm

Nonlinear mixed effects models are now widely used in biometrical studies, especially in pharmacokinetic research or for the analysis of growth traits for agricultural and laboratory species. Most of these studies, however, are often based on ML estimation procedures, which are known to be biased downwards. A few REML extensions have been proposed, but only for approximated methods. The aim of this paper is to present a REML implementation for nonlinear mixed effects models within an exact estimation scheme, based on an integration of the fixed effects and a stochastic estimation procedure. This method was implemented via a stochastic EM, namely the SAEM algorithm. The simulation study showed that the proposed REML estimation procedure considerably reduced the bias observed with the ML estimation, as well as the residual mean squared error of the variance parameter estimations, especially in the unbalanced cases. ML and REML based estimators of fixed effects were also compared via simulation. Although the two kinds of estimates were very close in terms of bias and mean square error, predictions of individual profiles were clearly improved when using REML vs. ML. An application of this estimation procedure is presented for the modelling of growth in lines of chicken.     

The influence of associative effects on the in vitro-estimated utilizable crude protein (uCP) of feeds for ruminants

Nineteen feed mixtures, formulated with 16 single feeds, were used to study the influence of associative effects on utilizable crude protein (uCP) of feed mixtures. The in vitro incubation technique of Zhao and Lebzien (2000) was used for uCP determination. It was found that the in vitro-determined uCP (D-uCP) was significantly higher than the weighted uCP (W-uCP) of feed mixtures and there was a significant regressive relationship between W-uCP (x) [g x kg(-1)DM] and D-uCP (y) [g x kg(-1)DM]: y=(0.94 +/- 0.23)x + (18.78 +/- 35.58), r2=0.49, n=19, p < 0.01. It was concluded that there exist significant associative effects of feed mixtures on uCP. In formulation of rations for ruminants the D-uCP should be used instead of W-uCP. Because of the low regression coefficient of the equation above, the D-uCP cannot be estimated from the W-uCP.