Metabolizable Energy Requirements Research Articles

Metabolizable amino acids and energy requirements of Nellore and crossbred Angus × Nellore bulls fed rations of different crude protein concentrations

Growth rate of cattle depends on their genetic makeup and nutrient intake. Moreover, increased growth rate may lead to increased amino acid (AA) requirements. Therefore, we evaluated the AA content of the empty body and estimated the net AA and energy requirements of purebred and crossbred beef bulls fed rations of different dietary CP concentrations. We performed a comparative slaughter experiment with 24 Nellore and 24 Angus × Nellore (A × N) bulls (8 months; initial shrunk BW: Nellore = 208.0 ± 12.78 kg; A × N = 221.9 ± 14.16 kg). Eight bulls (four Nellore and four A × N) were designated as the reference group, eight bulls (four Nellore and four A × N) were fed to maintenance level and 32 bulls (16 Nellore and 16 A × N) were fed ad libitum. The 32 bulls fed ad libitum were distributed using a completely randomized design in a 2 × 3 factorial scheme with two genetic groups (Nellore or A × N) and three dietary CP contents (100, 120 or 140 g CP/kg DM), being four groups with five bulls and two groups with six bulls. The experimental period lasted for 224 days. There were no interactions (P ≥ 0.056) between the dietary CP contents and genetic groups for any of the response variables. The dietary CP contents did not affect (P ≥ 0.062) the AA content in the empty body (g/kg empty BW [EBW]), with exception for Tryptophan (P = 0.027, linear effect). The dietary CP contents did not affect (P ≥ 0.051) AA content in the empty body (g/100 g of CP), with exception for Alanine (P = 0.013) that responded quadratically to dietary CP increase. The equations to estimate the net Lysine (Lys) and Methionine (Met) requirements (g/100 g of CP) were: Lys = 5.1 × EBW0.0594 and Met = 1.7 × EBW0.0255. Metabolizable Lys and Met to metabolizable energy (ME) ratios decreased as bulls EBW increased. Also, the metabolizable protein to ME ratio decreased as bulls EBW increased. In conclusion, the present study provides useful information regarding net and metabolizable requirements of AA of purebred and crossbred beef bulls. In the future, after the validation of the equations, these results can be used to calculate the AA requirements for growth of purebred and crossbred beef bulls. Nevertheless, it is important to highlight that the small sample size was one limitation of this present experiment.

279 Evaluation of the NRC (2012) model in estimating standard maintenance metabolizable energy requirement of PIC sows during mid-gestation

Abstract The objective was to evaluate the NRC (2012) model in predicting standard maintenance metabolizable energy (MEm) of PIC sows during mid-gestation. A total of 201 PIC Camborough sows (parity 1 to 10) were randomly assigned to 1 of 4 treatments in a complete randomized design between day 36 and 46 post-breeding. Treatments consisted of feeding sows with daily feed allowances to meet 80, 90, 100 or 110% of MEm calculated as MEm, kcal/day = 100 × (body weight)0.75. A common corn-soybean meal-based diet with 3,302 kcal of ME/kg and 0.61% standardized ileal digestible lysine was fed for 28 days. Sow body weight (BW) and sow body condition caliper score (CS) were captured at day 0, 14 and 28. Data were analyzed with PROC GLM of SAS with sow as experimental unit. Average sow parity and feed allowance were 4.2 and 1.79 kg/day, respectively. Average sow BW and sow CS at day 0, 14 and 28 were 234, 233 and 242 kg and 14.9, 14.9 and 14.8, respectively. Increasing feed allowances to meet 80 to 110% of MEm requirement increased (linear, P< 0.01) average daily gain (ADG; 0.100, 0.259, 0.417 and 0.440 kg/d, respectively). The estimated regression equation was ADG, kg/day = -0.83 + 1.193 × MEm, estimating the MEm to maintain BW was below 80% of NRC (2012) estimate. Caliper score change (CSC) increased (linear, P< 0.01) with increasing feed allowances to meet 80 to 110% of MEm requirement (-0.78, -0.26, 0.13, and 0.35, respectively). The estimated regression equation was CSC = -3.73 + 3.78 × MEm, estimating the MEm to maintain CS at 98.7% of NRC (2012) estimate. In summary, results showed that the MEm to maintain BW and CS for PIC sows during mid-gestation was below 80% and at 98.7%, respectively, of NRC (2012) estimated requirement.

Relative availability of metabolizable methionine from 2 ruminally protected sources of methionine fed to lactating dairy cattle

Our objective was to evaluate the lactational responses of dairy cows to methionine provided from 2 ruminally protected sources of methionine activity. Twenty-one Holstein dairy cows [11 primiparous (634 kg of body weight, 140 d in milk) and 10 second-parity (670 kg of body weight, 142 d in milk)] were assigned to a treatment sequence in 4 replicated 5 × 5 Latin squares plus 1 cow, with 14-d periods. Treatments were as follows: control; 7.5 or 15 g/d of a ruminally protected product of 2-hydoxy-4-methylthio-butyric acid (NTP-1401; Novus International Inc., St. Charles, MO); or 7.5 or 15 g/d of a ruminally protected dl-methionine product (Smartamine M; Adisseo, Alpharetta, GA). The diet was predicted to meet metabolizable protein and energy requirements. Diets contained 16.1% crude protein, and the control diet was predicted to be deficient in metabolizable methionine (1.85% of metabolizable protein) but sufficient in lysine (6.8% of metabolizable protein). Feed intake and milk yield were measured on d 11 to 14. Blood was collected on d 14. Dry matter intake, milk yield, energy-corrected milk, milk fat yield and percentage, and efficiencies of milk and energy-corrected milk yield were not affected by treatment. Milk protein percentage and milk protein yield increased linearly with supplementation, without differences between methionine sources or interactions between source and level. Linear regressions of milk protein percentage and milk protein yield against supplement amount within source led to slope ratios (NTP-1401:Smartamine M) of 95% for protein percentage and 84% for protein yield, with no differences between sources for increasing milk protein. Plasma methionine concentrations were increased linearly by methionine supplementation; the increase was greater for Smartamine M than for NTP-1401. Plasma d-methionine was increased only by Smartamine M. Plasma 2-hydoxy-4-methylthio-butyric acid was increased only by NTP-1401. Our data demonstrated that supplementation with these methionine sources can improve milk protein percentage and yield, and the 2 methionine sources did not differ in their effect on lactation performance or milk composition.

Energy Consumption of Young Military Working Dogs in Pre-Training in Germany.

Simple SummaryAppropriate energy supply adjusted to the requirements of military working dogs at pre-training is a basic prerequisite for working dogs, so they are fully able to exercise. Therefore, twenty Belgian Shepherds var. Malinois were accompanied for four weeks during pre-training as military working dogs, and the amount of energy intake was evaluated. Changes in body constitution were assessed by measuring body weight and shoulder height, as well as thickness of subcutaneous fat tissue, and of Musculus sacrocaudalis dorsalis lateralis (MSCDL). Energy intake amounted to, on average, 244 kcal/kg body weight (BW)0.75 daily. Changes to body constitution (increases in body weight, shoulder height, and thickness of the MSCDL, as well as a reduction of the thickness of the subcutaneous fat tissue lying on the MSCDL) might be attributed to training-induced muscle growth and physiological growth in size. In addition to training intensity, influences of ambient temperature and physiological body growth seemed to be important contributing factors in the supply of energy for military working dogs (MWDs) during pre-training.Many factors have specific effects, in varying degrees of intensity, on the metabolic energy requirements of working dogs. Appropriate energy supply adjusted to the requirements of military working dogs at pre-training is a basic prerequisite for working dogs, so they are fully able to exercise. Therefore, more knowledge obtained under standardized conditions would be advantageous. Twenty intact Belgian Shepherds var. Malinois at the age of 12 months were accompanied for four weeks during pre-training (odour detection, obedience training, and protection work) as military working dogs (MWDs) in Germany (ambient temperature about 7.8 °C), and the amount of energy intake was evaluated. To assess changes in body constitution, body weight and shoulder height were measured, and the thickness of subcutaneous fat tissue (SCF), and of Musculus sacrocaudalis dorsalis lateralis (MSCDL), were recorded via ultrasound. Energy intake amounted to, on average, 244 ± 34 kcal/kg body weight (BW)0.75 daily. Increases in body weight, shoulder height, and thickness of the MSCDL, as well as a reduction of SCF thickness lying on the MSCDL, were observed. Changes of body constitution might be attributed to training-induced muscle growth and physiological growth in size. In addition to training intensity, influences of ambient temperature and physiological body growth seemed to be important contributing factors in the supply of energy for MWDs during pre-training.

Multifaceted linkages among eco-physiological factors, seasonal plankton dynamics and selective feeding behavior of the green mussel (Perna viridis) in the south-east coast of the Bay of Bengal

Feeding behavior of marine bivalves is largely regulated by the interactive effects of various intrinsic biological factors and extrinsic ecological factors. Therefore, an integrated multivariate approach was applied to explore a deeper knowledge about the feeding biology of the green mussel (Perna viridis), collected from the south-east coastal regions of the Bay of Bengal in Bangladesh, by interlinking among ecological factors, seasonal plankton dynamics, reproductive traits and plankton ingestion data. The correlation test, multivariate approaches and cluster analysis displayed that both the water parameters and ingested gut plankton abundance and their compositions were predominantly influenced by the seasonality and ecological factors of the environment. The selectivity indices analysis confirmed that green mussels preferentially ingested on the selective taxa of plankton. The multivariate analyses revealed that plankton ingestion by green mussels was not discriminated by their sexual dimorphism, however, it displayed an enhancement during their gonad development and maturation stages confirming that P. viridis espouses opportunistic patterns to build up their gonads by utilizing energy from the ingested planktons available in the water column. The correlation outcomes consistently demonstrated that the quantitative ingestion of plankton was positively correlated with the gonadosomatic index value of the green mussels. Although, green mussels predominantly ingested the Coscinodiscophyceae (20–60% of total ingestion), they also selectively ingested an increased amount of Bacillariophyceae, Fragillariophyceae, Dinophyceae and zooplankton during their gonad development and maturation stages to meet the special and unique metabolic requirements of crucial gametogenesis stages. Taken together all datasets, principal component analysis (PCA) was applied: the first two principal components showed that seasonality and reproductive cycle explained >47% of the variability. In both cases, PCA analysis revealed that the multiplex scenario of selective ingestion of P. viridis on different plankton taxa were predominantly interlinked with the seasonality, ecological drivers, and plankton biomass and their community structure in the water column depending on the metabolic energy requirement during their crucial gametogenesis stages. Finally, the outcomes from these broad datasets provide a better understanding about the selective feeding behavior of P. viridis, which is essential to maintain the sustainability of the ecosystems as well as to improve the growth and productivity of the existing production systems of this important species.

Energy partitioning and energy efficiency of two Holstein genotypes under a mixed pasture-based system during mid and late lactation

The objective was to evaluate the effect of the Holstein genotype (North American Holstein vs. New Zealand Holstein; NAHvs.NZH, respectively) in a pasture-based system on heat production (HP), energy partitioning between maintenance and production (milk and tissue) and energy efficiency during two different stages of lactation. Twenty-eight Holstein dairy cows (14 cows of each genotype) with similar calving date (May 5, 2018 ± 23 days) were managed in a pasture-based system and supplemented with one third of the predicted total dry matter intake as concentrate. Heat production, retained energy in milk and tissue, metabolizable energy intake (MEI) and the proportion of MEI retained in milk + tissue (RE/MEI) were measured at 115 and 192 ± 19 days in milk and residual HP was estimated by the difference between measured HP and predicted HP based on NRC (2001) model according to body weight, body condition score and milk production. The NAH cows were 60 ± 15 kg heavier and produced 4.7 ± 1.0 kg/d more milk with lower percentages of fat and protein than NZH cows. However, there were no differences in fat or protein yield per day between genotypes. Metabolizable energy intake, retained energy in milk and tissue, HP and RE/MEI were not different between genotypes at 115 days in milk. Nevertheless, at 192 days in milk the MEI, HP and residual HP were lower in NZH than NAH, whereas RE/MEI was not different when both genotypes were managed under a pasture-based system with one third of the consumed diet as concentrate. The capacity of NZH cows to maintain the same RE/MEI than NAH cows at 192 days in milk despite of the lower MEI, was due to a lower metabolizable energy requirement for maintenance (853 vs. 729 kJ/body weight0.75 per day for NAH and NZH, respectively). Indeed, the lower energy requirement for maintenance in NZH was associated with a lower fasting heat production since kl were not different between genotypes. Thus, NZH cows could have a lower proportion of their body as protein mass or a lower relative mass of the internal organs involved with digestive and circulatory functions. However, further investigation is necessary to understand the differences in maintenance energy requirements between the Holstein genotypes.

Energy requirements for pregnant dairy cows.

This study aimed to estimate energy requirements of pregnant Holstein × Gyr cows. Different planes of nutrition were established by two feeding regimens: ad libitum or maintenance. Sixty-two nonlactating cows with average body weight of 480 ± 10.1 kg and an age of 5 ± 0.5 years were used. Cows were divided into three groups: pregnant (n = 44), non-pregnant (n = 12), and baseline reference (n = 6). The 56 pregnant and non-pregnant cows were randomly allocated into a feeding regimen: ad libitum or maintenance. To evaluate the effects of days of pregnancy, pregnant and non-pregnant animals were slaughtered at 140, 200, 240, and 270 days of pregnancy. Energy requirements for maintenance differed between pregnant and non-pregnant cows, thus two equations were developed. Net energy and metabolizable energy requirements for maintenance of non-pregnant cows were 82 kcal/kg empty body weight0.75/day and 132 kcal/kg empty body weight0.75/day, respectively. The efficiency of use of metabolizable energy for maintenance of non-pregnant cows was 62.4%. Net energy and metabolizable energy for maintenance of pregnant cows were 86 kcal/kg empty body weight0.75/day and 137 kcal/kg empty body weight0.75/day, respectively. Efficiency of use of metabolizable energy for maintenance of pregnant cows was 62.5%. The efficiency of use of metabolizable energy for gain was 41.9%. The efficiency of use of metabolizable energy for pregnancy was 14.1%. Furthermore, net energy requirement for pregnancy was different from zero from day 70 of pregnancy onwards. In conclusion, net energy and metabolizable energy requirements for maintenance of non-pregnant cows are different from pregnant cows. Furthermore, we believe that the proposed non-linear equations to estimate net energy requirements for pregnancy are more adequate than current NRC equation, and should be recommended for Holstein × Gyr cows.

The effect of diet-induced obesity and pasture on blood pressure and serum cortisol in Standardbred mares.

Obesity is associated with insulin resistance, vascular dysfunction and altered cortisol metabolism both in humans and in horses. Evaluate the effect of weight gain induced by a haylage diet low in nonstructural carbohydrates (NSC) on insulin sensitivity, blood pressure and serum cortisol concentrations. In vivo experiment. Nine adult Standardbred mares fed a fat supplemented haylage diet at 250% of the horses' daily metabolisable energy requirements for 22weeks. Horses were then turned out on pasture for 4weeks. Insulin sensitivity (SICLAMP ) was measured before and after weight gain and after 4weeks of pasture using the euglycemic hyperinsulinaemic clamp (EHC) method. Body condition score (BCS), blood pressure and serum cortisol were monitored throughout the study. All data were analysed using the linear mixed model procedure. Values of P<0.05 were considered as statistically different. All horses became obese during the weight gain period (BCS>7). Mean arterial blood pressure (MAP) increased during the weight gain period and was significantly higher than initial values at the end of the weight gain period (78±3mm Hg vs 92±3mmHg). MAP remained increased on pasture (93±3mmHg). SICLAMP was unaffected by weight gain 0.9±0.1 vs 1.0±0.1 ([mg/kg/min×103 ]/[µIU/mL×mmol/L])) but improved after pasture (1.6±0.1 ([mg/kg/min×103 ]/ [mU/L]). Serum cortisol concentrations increased during the weight gain period (80±9nmol/L vs 112±9nmol/L) and remained increased during pasture. Limited number of horses and no control group. Obesity was associated with a linear increase in blood pressure and an increase in serum cortisol that was not associated with insulin sensitivity.

Modeling life-time energy partitioning in broiler breeders with differing body weight and rearing photoperiods

Understanding energy partitioning in broiler breeders is needed to provide efficiency indicators for breeding purposes. This study compared 4 nonlinear models partitioning metabolizable energy (ME) intake to BW, average daily gain (ADG), and egg mass (EM) and described the effect of BW and rearing photoperiod on energy partitioning. Ross 708 broiler breeders (n = 180) were kept in 6 pens, controlling individual BW of free run birds with precision feeding stations. Half of the birds in each chamber were assigned to the breeder-recommended target BW curve (Standard) or to an accelerated target BW curve reaching the 21-week BW at week 18 (High). Pairs of chambers were randomly assigned to 8L:16D, 10L:14D, or 12L:12D rearing photoschedules and photostimulated with 16L:8D at week 21. Model [I] was: MEId = a × BWb + c × ADG × BWd + e × EM + ε, where MEId = daily ME intake (kcal/day); BW in kg; ADG in g/day; EM in g/day. Models [II–IV] were nonlinear mixed versions of model [I] and included individual [II], age-related [III], or both individual and age-related [IV] random terms to explain these sources of variation in maintenance requirement (a). Differences were reported as significant at P ≤ 0.05. The mean square error was 2,111, 1,532, 1,668, and 46 for models [I–IV] respectively, inferring extra random variation was explained by incorporating 1 or 2 random terms. Estimated ME partitioned to maintenance [IV] was 130.6 ± 1.15 kcal/kg0.58, and the ME requirement for ADG and EM were 0.63 ± 0.03 kcal/g/kg0.54 and 2.42 ± 0.04 kcal/g, respectively. During the laying period, maintenance estimates were 124.2 and 137.4 kcal/kg0.58 for standard and high BW treatment, and 130.7, 132.2, and 129.5 kcal/kg0.58 for the 8L:16D, 10L:14D, or 12L:12D treatments, respectively. Although hens on the standard BW treatment with a 12L:12D rearing photoschedule were most energetically conservative, their reproductive performance was the poorest. Model IV provided a new biologically sound method for estimation of life-time energy partitioning in broiler breeders including an age-related random term.

Efficiency of Crude Protein Utilisation in Grazing Dairy Cows: A Case Study Comparing Two Production Systems Differing in Intensification Level in New Zealand.

Simple SummaryImproving the dietary crude protein utilisation in dairy cows is a key aspect of agronomically and environmentally sustainable production systems. The intensification process of grazing dairy systems identified with the increase of milking cows linked with the addition of supplementary feed along with the increasing use, and particularly inefficient use, of nitrogen fertiliser, has led to increasing pressure on the environment. However, feeding solely on pasture could result in an excess of crude protein intake relative to nutritional requirements, and this could reduce the dietary crude protein utilisation. In this study, we modelled the dietary crude protein utilisation, along with nitrogen excreta partitioning of milking cows, of two contrasting spring-calving pasture-based herds differing in intensification level in New Zealand. We found that feeding diets with higher fresh pasture proportions, such as those employed in low-intensification dairy systems, led to an excess of crude protein intake with greater nitrogen partitioned towards urine, which is sensitive in terms of body water eutrophication. In the high-intensity production system, the inclusion of low-crude protein supplements resulted in better dietary crude protein utilisation, along with less urinary nitrogen losses.In this study, we modelled and compared lactation curves of efficiency of crude protein utilisation (ECPU) and the nitrogen (N) excreta partitioning of milking cows of two contrasting spring-calving pasture-based herds to test some aspects of farming intensification practices on cow performance and N partition. In the low-intensity production system (LIPS), 257 cows were milked once-daily and fed diets comprised of pasture with low supplementary feed inclusion during lactation (304 kg pasture silage/cow). In the high-intensity production system (HIPS), 207 cows were milked twice-daily and fed pasture with higher supplementary feed inclusion (429 kg pasture silage and 1695 kg concentrate/cow). The dietary crude protein (CP) utilisation was calculated for each cow at every herd test date as the ECPU as a proportion of protein yield (PY) from the CP intake (CPI) derived from intake assessments based on metabolisable energy requirements, and the CP balance (CPB) calculated as the difference between CPI and PY. Total N excreta partitioned to faeces (FN) and urine (UN) was estimated by back-calculating UN from FN, considering dietary N, and from N retained in body tissues, taking into account live weight change during the lactation. The higher CPI (2.7 vs. 2.5 kg CP/day), along with the reduced milk yield (1100 kg milk/cow less), of the LIPS cows led to a lower ECPU (23% vs. 31%) and to a higher CPB (2.1 vs. 1.8 kg CP/day) when compared to the HIPS cows. Mean N excreta, and particularly UN, was significantly higher in LIPS cows, and this was explained by higher dietary CP and by the reduced PY when compared to the HIPS cows. Reducing the low-CP supplementation in the “de-intensified” herd lessened the ECPU, resulting in higher UN, which is sensitive in terms of body water eutrophication.

Determination of energy and protein requirements for maintenance and lactation of Dorper × Hu crossbred sheep

Abstract This study set out to define the energy and protein requirements for maintenance and lactation of Dorper☓Hu crossbred lactating ewes. Eighteen ewes of similar weight (53.37 ± 1.18 kg) were randomly divided into three groups after parturition: ad libitum (AL), IR70 % (intake restricted to 70 % of AL), and IR50 % groups (intake restricted to 50 % of AL). Energy, nitrogen, and carbon balance were calculated by determining the carbon or nitrogen content of orts, feces, urine, milk, CH4, and CO2 samples in digestibility and respiratory trials. Maintenance requirements of net energy [NEm; 257.04 ± 1.15, 252.35 ± 1.08, 244.34 ± 1.15 kJ/kg body weight (BW)0.75/day]; metabolizable energy (MEm; 353.29 ± 3.27, 352.16 ± 3.54, 354.97 ± 2.67 kJ/kg BW0.75/day); net nitrogen (NNm; 326 ± 110, 306 ± 81, 285 ± 77 mg/kg BW0.75/day); and net protein (NPm; 2.03 ± 0.17, 1.91 ± 0.28, 1.78 ± 0.28 g/kg BW0.75/day) were observed on 20th, 50th and 80th day of lactation. Compared with these results, the Wood’s model showed adequate estimates of peak yield (0.88 vs. 0.87 kg/day), but an overestimation of milk yield either side of the peak, and an underestimation of the timing of peak yield compared with the observed milk curve in the current study (4th vs. 3rd week of lactation, respectively). The corresponding NE requirements for lactation (NEL; MJ/kg milk) linearly increased with progressing lactation and were scaled from 3.76 to 4.19 (MJ/kg milk). Additionally, milk yield varied from 1–3 kg daily, and, from 20th to 80th day of lactation, the daily metabolizable protein (MP) requirement for lactation ranged from 141.14–283.43 g/day. The combined results suggest that the estimated MP and ME requirements for lactating Dorper and Hu crossbred sheep fell between the NRC recommendations for lactating ewes suckling a singleton and twin lambs.

Energy requirements for maintenance and growth of young pre-ruminant Angora goats

Abstract There is little information available on the nutrient requirements of suckling Angora kids weighing less than 10 kg which has resulted in nutrition recommendations being based on older, heavier and weaned goats. This experiment determined the energy intake of suckling Angora kids to estimate maintenance ME requirement (MEm) and ME required for growth (MEg) for 8 and 21 day old kids. Does were housed in individual pens in an outdoor feedlot from day 47 of pregnancy. Pregnant does experienced a range of controlled nutrition treatments providing a range in live weight and body condition at kidding. From 4 days postpartum treatments were: ad libitum (AL) to allow maximum ME intake resulting in doe live weight gain; or Restricted (R) to 70% of AL, resulting in doe live weight loss until week 10 of lactation. Doe milk production was determined at days 8 and 21 of lactation, and ME intake of milk, kid liveweight change and fibre growth rate were determined. ME intake (kJ/kg0.75day) was then related to daily liveweight gain (g/kg0.75day) using multiple linear regression analysis. At 8 days of age, MEm = 1199 kJ/kg0.75day and MEg = 35.6 kJ/kg0.75day (P = 0.002). At 21 days of age, MEm = 700 kJ/kg0.75day (NS) and MEg = 24.0 kJ/kg0.75day (P

Evaluation of the Modified LIVestock SIMulator for Stall-Fed Dairy Cattle in the Tropics.

Simple SummaryModels can play an important role in identifying and filling knowledge gaps related to sustainable resource use in (sub-)tropical livestock production systems. Yet, most simulation models used to study cattle production systems in the (Sub-)Tropics were developed using data that quantify and characterize biological processes of cattle kept in temperate regions, which may reduce the accuracy of predictions. Therefore, we adopted some published data that quantify and characterize biological processes of cattle kept in (sub-)tropical production systems to modify an existing ruminant livestock herd model. Then, the accuracy of predictions of feed intake and productive performance from the original and modified models were evaluated using meta data from (sub-)tropical stall-fed cattle. The modified model predicted voluntary dry matter intake and productive performance more accurately than the original model. Consequently, adopting relevant data that correctly describe the biological processes in (sub-)tropical cattle production systems is the way forward for improving simulation models for these systems.Ruminant livestock systems in the (Sub-)Tropics differ from those in temperate areas. Yet, simulation models used to study resource use and productive performance in (sub-)tropical cattle production systems were mostly developed using data that quantify and characterize biological processes and their outcomes in cattle kept in temperate regions. Ergo, we selected the LIVestock SIMulator (LIVSIM) model, modified its cattle growth and lactation modules, adjusted the estimation of the animals’ metabolizable energy and protein requirements, and adopted a semi-mechanistic feed intake prediction model developed for (sub-)tropical stall-fed cattle. The original and modified LIVSIM were evaluated using a meta-dataset from stall-fed dairy cattle in Ethiopia, and the mean bias error (MBE), the root mean squared error of prediction (RMSEP), and the relative prediction error (RPE) were used to assess their accuracy. The modified LIVSIM provided more accurate predictions of voluntary dry matter intake, final body weights 140 days postpartum, and daily milk yields than the original LIVSIM, as shown by a lower MBE, RMSEP, and RPE. Therefore, using data that quantify and characterize biological processes from (sub-)tropical cattle production systems in simulation models used in the (Sub-)Tropics can considerably improve their accuracy.

Enteric methane emissions in crossbred heifers fed a basal ration of low-quality tropical grass supplemented with different nitrogen sources

The aim of the present study was to assess enteric methane (CH&lt;sub&gt;4&lt;/sub&gt;) emissions by crossbred heifers fed a basal ration of low-quality tropical grass supplemented with different nitrogen sources. Four crossbred heifers (Bos taurus × Bos indicus) with an average live weight (LW) of 355 ± 6.01 kg were used in a 4 × 4 crossover Latin square design with four periods of fifteen days each. Basal ration was chopped low-quality tropical grass Pennisetum purpureum fed to cover ~70% of metabolizable energy requirements for maintenance of heifers and it was supplemented with either poultry litter (control ration, T1), urea (T2), canola meal (T3) or soybean meal (T4). Enteric CH&lt;sub&gt;4&lt;/sub&gt; emissions of heifers were measured in open-circuit respiration chambers for 23 hours. Dry matter (DM), neutral detergent fibre (NDF) and acid detergent fibre (ADF) intakes decreased when feeding urea (1.6% of ration) as a source of nitrogen (7.64, 3.78, and 1.83 kg/d, respectively). Rations including urea (T2) or canola meal (T3) given to heifers fed a basal ration of low-quality Pennisetum purpureum grass significantly reduced acetic acid concentration and increased propionic acid concentration in the rumen and decreased the loss of gross energy as methane (P = 0.004). Incorporation of urea or canola meal in the ration of cattle fed low-quality tropical grass can decrease methane emissions and improve rumen fermentation patterns.

Intensification of cow-calf production: How does the system respond biologically to energy inputs in a long-term horizon?

In southern Brazil, beef cattle production systems generally rely on grazing on natural pastures. However, their forage production, and consequently metabolizable energy (ME) production, is seasonal and influenced by climatic events. Thus, there is a scientific and commercial interest in evaluating and understanding the biological impacts of intensification using pasture irrigation and the effects of El Niño-Southern Oscillation (ENSO) phenomena on the long term on the productivity of cow-calf systems. Therefore, our objective was to develop a simulation model to evaluate the effects of intensification levels, using cultivated pastures and irrigation, on the productivity and on the efficiency metabolizable energy utilization of beef cow-calf systems in a 10-year horizon. This period allows capturing the effects of several production cycles as influenced by ENSO events. The model includes three submodels: herd structure, herd ME requirements, and forage ME production. The results of the present study demonstrate that the proposed model is able to evaluate the influence of intensification of grazing systems on metabolizable energy production, carrying capacity, productivity and biological efficiency of beef cow-calf systems over a long-term horizon. Productivity was increased in 15.9% when 20% of the grazing area was intensified and irrigated compared with the modeled non-intensified system, independently of climatic events. The main productive response was the increase in the number of dams in the herd, especially as a result of the use of irrigation. This study proposes different alternatives for increasing the productivity of beef cow-calf systems in southern Brazil.

Arsenal of Phytochemicals to Combat Against Arsenic-Induced Mitochondrial Stress and Cancer.

Significance: Phytochemicals are important dietary constituents with antioxidant properties. They affect various signaling pathways involved in the overall maintenance of interior milieu of the cell. Arsenic, an environmental toxicant, is well known for its deleterious consequences, such as various diseases, including cancers in humans. Mitochondria are the cell's powerhouse that fuel all metabolic energy requirements. Dysfunctional mitochondria due to stressors may lead to abnormal functioning of the organelle, hampering the crucial cellular cross talks and ultimately leading to cancer. Application of phytochemicals against arsenic-induced mitochondrial disorders may be a preventive measure to counteract the ruinous impacts of the metalloid. Recent Advances: In recent years, extensive research on the role of mitochondria in cancer gives a better understanding of the areas the organelle covers in maintaining a healthy cell or in inducing carcinogenicity. Detailed knowledge of the mitochondrial governances would enable researchers to administer numerous phytochemicals to ameliorate altered oxidative phosphorylation, mitochondrial membrane potential (MMP), mitochondrial oxidative stress, unfolded protein response, glycolysis, or even apoptosis. Critical Issues: In this review, we have addressed how various phytochemicals belonging to diverse classes combat against arsenic-induced mitochondrial oxidative stress, depletion of MMP, cell cycle abrogation, apoptosis, glycolytic damages, oncogenic regulations, chaperones, mitochondrial complexes, and mitochondrial membrane pore formation in both in vitro and in vivo models. Future Directions: Insightful application of mitoprotective phytochemicals against arsenic-induced mitochondrial oxidative stress and carcinogenesis may guide researchers to develop preclinical chemopreventive agents to fight arsenic toxicity in humans.

Dietary Fatty Acid Composition Influences Growth Performance and Hepatic Metabolism in Neonatal Pigs

Medium‐chain fatty acids (MCFA) are often included in neonatal milk formulas as a more readily oxidized source of energy compared with long‐chain fatty acids (LCFA). This rapid oxidation of MCFA is thought to enhance growth. Thus, the objectives of this study were to evaluate the effect of energy supplementation and fat source on growth and body composition, and determine the rate of Krebs Cycle substrate utilization in neonatal pigs. Eleven three‐day‐old pigs were allocated to one of three sow milk replacer formulas: a control (CONT) and diets rich in either LCFA or MCFA. The CONT formula provided 80%, whereas the MCFA and LCFA formulas provided 120%, of the metabolizable energy requirements of neonatal pigs. Pigs were fed for 20 days and body composition measured by DXA before initiation and on day 20 of feeding. At the end of the study, pigs were euthanized and muscles and organs collected and weighed. Livers were digested with collagenase and isolated hepatocytes were incubated in media containing all amino acids, glucose, and short‐chain fatty acids in the presence of [U13C] labeled alanine, glucose, propionate, and glutamate for 90 min. The enrichment of Krebs Cycle intermediates was determined using gas chromatography/mass spectrometry. Body weight of pigs in the LCFA group was greater than those in the MCFA and CONT groups on days 18 and 20. In addition, percent fat measured by DXA was greater for MCFA (8%) and LCFA (7%) than those in the CONT (4%) group, and this increase in fat deposition occurred at the expense of lean tissue (P &lt; 0.05). Longissimus dorsi and heart weights as percent of body weight were similar for all groups; however, soleus weight was less for MCFA compared with those in the CONT and LCFA groups. In addition, liver and kidney weights as a percentage of body weight were greater for pigs in the MCFA group compared with those in the CONT group with LCFA being intermediate (P&lt; 0.05). There was no effect of formula feeding on glucose and alanine contribution to lactate synthesis in isolated hepatocytes, but this contribution was greater for glucose (36%) than for alanine (15%) (P&lt;0.05). Conversely, the contribution of alanine (35%) carbon to pyruvate was greater than the contribution of glucose (7%) (P&lt;0.05). Furthermore, in hepatocytes of pigs fed CONT formula 39% of pyruvate carbon was derived from alanine and 31–34% for pigs in the LCFA and MCFA groups (P&lt;0.05). Lastly, glutamate contributed 64% of α‐ketoglutarate carbon in hepatocytes of CONT and MCFA and only 40% for LCFA pigs. These data suggest that dietary MCFA increase body fat without increasing lean tissue accretion compared with CONT. In addition, anaplerosis from glutamate was greater for pigs fed MCFA and CONT than for those fed LCFA.

Effect of dietary protein to energy ratio of milk replacer on growth and body composition of pre-weaned lambs reared artificially

This study aimed to determine the effect of changing the dietary crude protein to metabolisable energy ratio (CP:ME) of milk replacer on growth and body composition of pre-weaned lambs. Thirty-two Romney twin-born ram lambs were selected with four lambs being slaughtered at 24 h post-partum to estimate initial body composition. The remaining twenty-eight lambs were assigned to one of three nutritional treatments. Treatments consisted of either (i) a commercial milk replacer (CMR, n = 10); (ii) a high protein milk replacer (HPM, n = 9) or (iii) a mix of normal milk replacer and milk protein concentrate (MB, n = 9). All lambs were fed at 2.1 times their maintenance requirement. The CP:ME ratio of MB was adjusted twice-weekly to match the lambs CP and ME requirements for growth and maintenance over time. All lambs were slaughtered at 22 kg live weight (LW). The LW and chemical composition of carcass and viscera plus blood were determined. The combined CP:ME ratio of milk and pellets was greater for the HPM lambs than MB lambs, which was greater (P < 0.0001) than CMR lambs. Daily ME intake was greater (P < 0.05) in MB compared to HPM and CMR, which did not differ (P > 0.05). Average daily LW gain was higher (P < 0.05) in both HPM and MB lambs than CMR lambs. The ME and CP intakes per kilogram LW gain were greater (P < 0.05) for CMR and HPM lambs, respectively than MB lambs. Omental fat content at slaughter was lowest (P < 0.05) and gut fill was greatest (P < 0.05) in HPM, while CMR and MB did not differ (P > 0.05) for either parameters. Fat content of the carcass and viscera plus blood was lowest (P < 0.05) in HPM whilst, there was no difference (P > 0.05) between CMR and MB. Lambs fed HPM had lower (P < 0.05) daily fat deposition than CMR, which was highest (P < 0.05) in MB. Daily dry matter deposition was greater (P < 0.05) in MB than both CMR and MB, which did not differ (P > 0.05). In conclusion, adjusting the CP:ME ratio of milk replacer to match the lambs’ theoretical requirement improves growth performance of artificially reared lambs. Further studies are required to determine the optimal CP:ME ratio effect of milk replacer, its cost effectiveness and to examine post-weaning growth effects.

Demographics, body condition scores and feeding of aged horses (≥20 years of age) - a Swedish survey

The proportion of aged horses (≥ 20 years old) is increasing in several horse populations, but knowledge of if any nutritional requirements change with age is scarce. An internet-based survey directed towards owners of horses ≥20 years of age was conducted, in order to collect data on demographics, body condition scores (BCS) and feeding practices of aged horses. Total complete responses included were 1443. Approximately 70% of the horses were 20–25 years old, 24% was 26–30 years old and the remaining proportion 31–42 years old. Approximately 40 different breeds were represented. Geldings comprised 57%, mares 42% and stallions 1% of the study population. A majority of the respondents reported moderate to ideal BCS in their horse. Validation of respondent assessment of BCS was performed for 21 horses, where kappa coefficient for agreement was 0.35. Respondents generally underestimated the BCS of their horse. Average age was higher in the lowest BCS compared to higher BCS. Average amount of forage fed daily was 1.5 kg DM per 100 kg BW (sd 0.48 kg per 100 kg BW), and average amount of concentrates fed daily was 0.11 kg per 100 kg BW (sd 0.160 kg per100 kg BW). Commonly used feeds were haylage and commercial concentrates. Horses with BCS 1 (n = 1), 2 (n = 19), 3 (n = 48) and 4 (n = 14) were calculated to be fed 64, 99, 108 and 127% of their estimated theoretical requirement of metabolisable energy (ME), indicating that aged horses may require about 1.1 the theoretical ME requirement to keep a desired BCS. However, controlled studies are required for further insights of if, and how, energy requirements change with increasing age in horses.

Energy and protein requirements of crossbred Holstein × Gyr calves fed milk with milk replacer containing increasing dry-matter concentrations

Context There is a lack of studies concerning the nutrient requirements of dairy calves, mainly, evaluating different genetic groups. Aims The objective was to quantify energy and protein requirements of dairy calves up to 60 days, testing the influence of genetic composition (Holstein or crossbred Holstein × Gyr) on these requirements. Methods The study involved 42 bull calves (3 days of age), including animals with less than 15/16 Holstein composition (considered crossbred) and animals with more than 15/16 Holstein pedigree (considered purebred). Six calves were slaughtered at the start of the experiment to estimate the initial body composition of the animals. Of the remaining animals, four formed the maintenance group (fed 3 L/day of raw milk), and the other 32 were distributed into four treatments, which consisted of 6 L/day of raw milk, with increasing DM contents of 13.5%, 16.1%, 18.2% and 20.4% respectively. The DM contents were corrected for adding milk replacer to the raw milk. All animals had free access to starter feed and water. Digestibility trials were conducted at 28 and 56 days of life, with total faeces collection being performed for 5 days and urine collection for a period of 24 h. At 60 days of life, the animals were slaughtered to determine their body composition. Key results Net energy requirements for maintenance and metabolisable energy requirements for maintenance were 57.6 and 86.8 kcal/(empty bodyweight, EBW)0.75.day respectively. The efficiency of utilisation of metabolisable energy for maintenance was 66%. Net energy requirements for gain (NEg, Mcal/day) can be estimated by the following equation: , where EBG is empty body gain (kg/day) and EBW is in kilograms. The efficiency of utilisation of metabolisable energy for gain was 27%. The metabolisable-protein requirement for maintenance was 3.22 g/EBW0.75.day. Net protein requirement for gain (NPg, g/day) can be estimated by the following equation:, where RE is retained energy (Mcal/day). The efficiency of utilisation of metabolisable protein for gain was 59.1%. Conclusions Genetic group does not affect energy or protein requirements of pre-weaned calves. The estimates presented here can be used to calculate nutrient requirements of pre-weaned calves aged up to 60 days. Implications Inclusion of milk replacer in the liquid feed had a negative impact on diet quality.