Dietary Metabolizable Energy Research Articles

What is dietary metabolisable energy?

Metabolisable energy (ME) is frequently used as the sole indicator of forage quality by researchers, rural professionals and farmers, but it is hardly ever measured and is not always a good predictor of feeding value. Forage ME is usually calculated from chemical composition and digestibility, often by near infrared reflectance spectroscopy (NIRS). Although ME is superior to dry matter (DM) as a measure of feeding value and can indicate forage quality, it should not be used to predict animal production. The ME content of DM may imply a potential for production, but other components of the diet, especially protein, structural fibre and feed availability will provide more information than ME alone. Researchers, rural professionals and farmers should understand the basis for measuring ME, exercise discretion when using ME, and include fibre and protein concentrations in their criteria for feed appraisal. Keywords: metabolisable energy, forage quality, feeding value

Effect of diet thermal treatment on excretion and digestibility in broiler chickens

Three hundred and twenty 1-d-old chicks (Ross 508 strain) were divided into 2 groups. Up to 56 d of age 2 group fed as meal a commercial diet (C), while the other group received the C diet submitted to a further thermal mal process (Buhler technology, DTMT4000) which hygenize the meal by the addition of steam (diet T), up to the mass temperature of 85°C for 180 sec, followed by drying for 90 sec, obtaining the Sanix diet of Natcor s.n.c. Ac 33 d of age, 8 chicks per treatment (sex balanced) were allocated to individual cages provided with individual feeder, drinker, steel tray for total collection of excreta. Digestibility trial lasted 5 d, according to the protocol of Francesch et al. (2002) and, to measure the dietary Apparent Metabolisable Energy (AME), the European reference method of Bourdillon et al. (1990) was followed. Diets were analysed for chemical composition, starch, filter fractions and GE contents. ANOVA tested the diet, the gender and their interactions as fixed effects. Thermal heat treatment increased the content of crude fat but reduced the content of starch of T diets, resulting in a moderate increase of the gross energy content. The analysed composition of C and T diets (as-fed basis) was, respectively: CP 20.1 and 19.7%; EE 7.2 and 8.7%; crude fibre 2.8 and 2.7%; ash 5.5 and 5.7%; starch 35.0 and 33Θ% GE 17.05 and 17.30 MJ/kg. Compared to C diet, the steam treatment of the T diet significantly reduced the fresh excretion (484 vs 578g; P<0.05) but increased the excretion of the DM (22 vs 17%; P<0.001). The digestibility of the nutrients was not affected by the diets except for the ash that was higher in T diet than in C diet (31.9M 21.1%; P<0.001). The digestibility of the other nutrients of C and T diet was, respectively: dDM 67.0 and 66.9% dEE 70.2 and 70.2%; dStarch 97.7 and 97.2%; dNDF 11.7 and 12.8%; dEnergy 70.8 and 70.0%; AME 13.7 and 13.7 MJ/kg DM. Retained protein was 60.4% for C diet and 62.7% for T diet. The digestibility of the nutrients was not affected by the gender even if males were on average heavier than females (1936 vs 1700g; P<0.05) and produced greater fresh excreta (572 vs 490g; P<0.05). It can be concluded that the meal hygenization with this particular steaming process seems to be advantageous from the bird's health point of view, by the way of production of more concentrate droppings, that represents a positive effect on the litter and on the air qualities.

Effects of dietary metabolisable energy, calcium and phosphorus on bone mineralisation, leg weakness and performance of broiler chickens

1. Performance, gait score (GS), tibial dyschondroplasia (TD), and tibia bone mineralisation and breaking strength were determined in 2880 male and female Ross 208 broilers fed on diets with two different concentrations of dietary metabolisable energy (ME) (11·00 or 12·00 MJ/kg) and 4 different concentrations of available phosphorus (aP) adjusted for dietary ME content (4·0, 4·5, 5·0 or 5·5 g/kg aP in starter and 3·5, 4·0, 4·5 or 5·0 g/kg aP in finisher diets containing 12·00 MJ/kg). 2. Tibia ash, calcium (Ca) and phosphorus (P) contents in broilers given diets with low ME (11·00 MJ/kg) were greater than those of broilers given diets with higher ME (12·00 MJ/kg). Tibia ash, Ca and P contents increased curvilinearly with increasing dietary aP content. The dietary aP level had no effect on GS. 3. Dietary concentration of ME or aP had no effect on tibia breaking strength. 4. Walking ability, as measured by GS, was negatively correlated with the body weight (BW) of tested birds at 23 and 35 d of age, but the dietary ME content or aP level had no significant effect on GS at 35 d of age. 5. The results indicated that bone mineral content had no clear correlation with the walking ability of broilers.

Growth and Carcass Characteristics of French Guinea Broilers Fed Diets with Varying Concentrations of Metabolizable Energy

ABSTRACT The potential for guinea fowl (Numida meleagris) production in the US as alternative poultry is a promising enterprise. However, scientific literature on their nutrient requirements is very limited. The objective of this study was to evaluate optimum dietary metabolizable energy (ME) for growth performance and carcass characteristics of French guinea broilers. Two hundred and twenty straight-run day old French guinea keets were randomly assigned to starter diets varying in ME concentration (2800, 2900, 3000, 3100 or 3200 ME kcal/kg diet) with identical crude protein (CP) content (23%) from hatch to 4 weeks of age (WOA). From 5-8 WOA, the diets were formulated to contain 2850, 2950, 3050, 3150 or 3250 ME kcal/kg diet, respectively, and 21% CP. Each 100 ME kcal/kg increase was associated with significant (P < 0.05) decrease in feed consumption such that birds on 2900 and 3000 ME Kcal/kg diet consumed 2.5 and 1.8% less feed than birds on 2800 and 2900 ME kcal/kg diet, respectively. Birds on 3100 and 3200 ME kcal/kg diet were more than 10% heavier (P < 0.05) than birds receiving diets of lower ME. Mean feed conversion ratio (FCR) of birds on 3100 and 3200 ME kcal/kg diet was lower (P < 0.05) than for birds on 3000 and 2900 ME kcal/kg diet. Mean eviscerated carcass weight was higher (P < 0.05) in guinea broilers receiving 3100 ME kcal/kg diet than other treatment groups. The weight of breast, thigh and drumstick of birds on 3100 and 3200 ME kcal/kg diet were not different, but were higher than all other treatment groups. While abdominal fat weight was directly proportional to dietary metabolizable energy levels, differences in weights of heart, liver and gizzard were not significant among the dietary metabolizable energy levels. Positive and highly significant correlations (P < 0.01) were noted between live weight and weight of carcass, breast, thigh and drumstick of French guinea broilers. Thus, based on this study, at 21% CP levels French guinea broilers will utilize more efficiently diets containing 3100 and 3150 ME kcal/kg diet at 0-4 and 5-8 WOA, respectively.

Effects of Dairy Cow Genotype with Two Planes of Nutrition on Energy Partitioning Between Milk and Body Tissue

The data used in the present study were derived from a 2 (genotype) × 2 (plane of nutrition) factorial design production study using Holstein-Friesian (n = 32) and Norwegian (n = 32) first-lactation dairy cattle offered grass silage-based diets from 1 to 44 wk of lactation. The high nutrition diet had concentrate inclusions (g/kg of dry matter) of 600, 500, and 400 for lactation days of <101, 101 to 200, and >200, respectively, and the low nutrition diet included concentrates at 300, 200, and 100 for the same periods. Dietary metabolizable energy (ME) concentrations were measured in calorimetric chambers at lactation d 80, 160, and 240 respectively, and then applied to production data to calculate ME intake. From wk 1 to 44 of lactation, Holstein-Friesian cows had a consistently lower accumulated live weight gain and body condition score, and a consistently higher ME intake and milk energy output than Norwegian cows, irrespective of the plane of nutrition. Compared with Norwegian cows using mean data derived from the 2 planes of nutrition, Holstein-Friesian cows produced a significantly higher proportion of milk energy output over ME intake in early and mid lactation, although this increase was not significant in late lactation. In contrast, Holstein-Friesian cows partitioned a significantly lower proportion of ME intake into body tissue than Norwegian cows in early lactation, although the differences were not significant in mid or late lactation. When ME intake and energy used for maintenance, milk, and body tissue were taken into account, the efficiency of ME use for lactation was similar between the 2 genotypes offered the high or low concentrate diet during the whole lactation. It is concluded that Holstein-Friesian cows can produce more milk energy than Norwegian cows, mainly as a result of higher ME intake and because of a greater ability to partition more energy into milk and less into body tissue. The effect on energy partitioning mainly occurs in early and midlactation and is particularly evident with high concentrate diets.

Effect of Bird Cage Space and Dietary Metabolizable Energy Level on Production Parameters in Laying Hens

A study was conducted to assess the effects of varying cage spaces on a commercial laying hen strain fed differing levels of dietary metabolizable energy (ME) for 15 wk. Four cage space allowances (342, 413, 516, and 690 cm2/hen) were combined with 3 levels of dietary ME (2,800, 2,850, and 2,900 kcal of ME/kg) in a 4 × 3 factorial arrangement. Each treatment was assigned to 6 replicate cages for a total of 72 cages in randomized complete block design. Feed intake and metabolizable energy intake were significantly (P < 0.01) greater for hens housed at 690 cm2/hen compared with those housed at 413 and 342 cm2/hen, but not those housed at 516 cm2/hen, across all dietary ME levels. Egg production and egg mass were significantly (P < 0.001) improved for hens housed at 690 cm2/ hen in contrast to other cage spaces and across all energy levels. There were no interaction effects of ME levels on laying hen performance at varying cage space except for body weight change. Hens housed at 516 cm2/ hen and fed 2,800 kcal of ME/kg exhibited the greatest weight change, which was significantly (P < 0.05) greater than those fed other levels of ME at the same cage space. Hens housed at 690 cm2/hen had significantly (P < 0.05) greater ME efficiency of egg production than hens housed at other cage spaces. Hens fed the diet with 2,900 kcal of ME/kg had significantly (P < 0.001) greater ME digestibility compared with those fed 2,800 or 2,580 kcal of ME/ kg with differences of 107 and 118 kcal of ME/kg, respectively. There were no significant effects of ME levels observed except ME digestibility, and no significant effects of cage space allowance on egg weight, hen weight, bone ash, or maintenance energy intake. It is evident that decreasing the number of birds per cage and increasing cage space allowance per hen had an overall positive effect on performance.

Effect of Varying Levels of Energy and Protein on Live Performance and Carcass Characteristics of Broiler Chicks

An experiment involving 270 straight run one-day-old Hubbard broiler chicks was conducted on floor pens to investigate the effect of different levels of energy and protein on live performance and carcass responses of broilers chicks. Six broiler starter diets with two levels of metabolizable energy (ME) i.e., 2800 and 3000kcal/kg each with three levels of crude protein (CP) i.e., 20, 21 and 22% were offered to birds from hatching to 28d of age. Similarly, six broiler finisher diets with two levels of ME i.e. 3000 and 3200kcal/kg and 3 levels of CP i.e. 16, 17 and 18%, and 18, 19 and 20%, respectively, were offered during 29-42d of age. The chicks were randomly divided into 18 replicate of 15 chicks each and there were 3 replicates under each diet. Feed intake was significantly (p<0.05) high in diet having low ME during both phase, with 20 and 22% CP during starter phase whereas all CP levels showed non-significant effects on feed intake at finisher phase. Low ME and high CP diets showed high feed intake (p<0.05) during starter and finisher phases. Higher weight gains (p<0.05) were observed at low ME diets during the experiment. Dietary CP contents at low ME did not affect the weight gain during starter phase whereas high CP with low ME showed high weight gain in finisher phase. The response of CP and ME was similar for good feed conversion ratio (FCR) as was observed for feed intake and weight gain. No significant differences of dietary treatments were observed on any of the carcass characteristics. From the recent study, it is obvious that low ME and high CP diets promised optimum performance for broiler chicks at both starter and finisher phases.

Fibre digestion and utilization in goats

Dietary fibre contributes significantly to the balancing of nutrient requirements in goats. Dietary fibre also plays a pivotal role in goat production through its influence in and interaction with the intake and digestion of nutrients. Physiological regulation (feedback from metabolic factors) of intake is dominant in goats fed high concentrate diets, while physical fill is the predominant factor in the regulation of intake when goats were fed high-forage diets. Mediated through salivation and buffering capacity, dietary fibre intake influences mastication and rumen fermentation. In growing goats, dietary metabolizable energy density above 2.78 Mcal/kg depresses intake and reduces growth rate in goats. Adequate dietary fibre is essential in producing leaner carcasses in growing goats. In high producing lactating dairy goats, dietary fibre intake plays a role in the prevention of milk fat depression. The effect is mediated through the maintenance of favorable acetate to propionate ratio in the rumen liquor, as acetate is the major precursor of milk fat. It appears that 18–20% ADF or 41% NDF is nutritionally adequate for high producing lactating dairy goats. For growing goats between 4 and 8 months of age, 23% ADF is recommended. Relationship between chewing time and dietary fibre can be defined by the equation: total chewing time (min/day) = 33.11 + 30.13 ADF intake (%). Milk fat yield can be predicted from dietary fibre intake: milk fat yield (g/day) = 115.78 − 0.128 × ADF intake (g/day) + 0.00021 × (ADF intake, g/day) 2.

Effects of dietary metabolizable energy and crude protein concentrations on growth performance and carcass characteristics of French guinea broilers

This study was undertaken to assess dietary CP and ME concentrations for optimum growth performance and carcass characteristics of French guinea broilers. In a 3 x 3 factorial arrangement, 396 1-d-old French guinea keets were randomly assigned to experimental diets with 3,050, 3,100, and 3,150 kcal of ME/kg of diet; each contained 21, 23, and 25% CP, respectively, from 0 to 4 wk of age (WOA). From 5 to 8 WOA, experimental diets had 3,100, 3,150, and 3,200 kcal of ME/kg of diet, and each contained 19, 21, and 23% CP, respectively. Each dietary treatment was replicated 3 times, and feed and water were provided ad libitum. Body weight and feed consumption were measured weekly, whereas carcass characteristics were evaluated at 8 WOA. For the most part, birds on 3,100 and 3,150 kcal of ME/kg of diet at 0 to 4 WOA exhibited greater (P < 0.05) BW gain, greater carcass and breast weights (P < 0.05), and lower (P < 0.05) feed consumption and feed conversion ratios (FCR) than those on a diet with 3,050 kcal of ME/kg. Mean feed consumption of birds fed 25% CP diets was higher (P < 0.05) than those on other dietary CP concentrations. Mean BW gain, FCR, and carcass and breast weights of birds fed 25 and 23% CP diets from 0 to 4 WOA were not different (P > 0.05), but they were better (P < 0.05) than those of birds on 21% CP diets. Positive correlations (P < 0.01) were noted between live weight and weight of carcass, breast, thigh, drumstick, and wing of guinea broilers. Thus, diets with 3,100 kcal of ME/kg and 23% CP or with 3,150 kcal of ME/kg and 21% CP at 0 to 4 WOA and 5 to 8 WOA, respectively, were used more efficiently by French guinea broilers.

Performance of Omani goats fed diets containing various metabolizable energy densities

A feeding trial was carried out to study feedlot performance of Omani Batina and Dhofari goats fed diets containing low, medium and high metabolizable energy (ME) levels. Animals were individually fed diets containing three levels of ME (8.81, 9.95 or 11.22 M/J kg DM) for 140 d. Feed intake as percentage of DM in body weight (BW) and metabolic body weight (BW 0.75) (MBW) in Omani goats of various breed/ME level combinations ranged between 2.8–3.2 and 5.8–6.5, respectively with no significant effects of diet, breed, or their interactions. There was a significant increasing body weight gain pattern with increasing ME density. Batina and Dhofari goats on highest ME gained more daily weight (96 and 53 g/d) thus reaching higher BW (27.7 and 21.7 kg) at week 20 of experiment than goats on medium (80 and 53 g/d; 25 g and 21.6 kg) and lower (50 and 46 g/d; 21.4 and 20.7 kg) ME diets, respectively. In general, Batina goats grew faster and reached higher BW than Dhofari. For all ME densities, Batina goats had better feed conversion ratio (FCR) than Dhofari. Increasing ME levels in the diet of goats increased carcass weight, empty body weight (EBW), dressing out percentage, chemical fat but decreased crude protein in the carcasses. ME requirements were calculated by regressing daily gain versus energy intake. This study indicated that raising Omani goats under feedlot systems on high ME diets or supplementing free grazing stock with energy sources will improve their growth rates and carcass composition.

Energy and protein metabolism in lactating sows fed two levels of dietary fat

The effect of feeding lactating sows with low (LF) or high (HF) dietary fat level (31 vs. 113 g crude fat per kg DM) was studied. Four sows on each diet were subjected to three balance and respiration experiments in weeks 2–4 of lactation. The contribution of piglet heat production (HE) to overall HE of sow and piglets (measured by indirect calorimetry) was measured by the doubly labelled water (DLW) technique in three piglets per litter. The nitrogen balance of the sow decreased with progress of lactation, with no dietary effect. Milk production, estimated by deuterium oxide (D 2O) dilution in DLW enriched piglets, increased ( P<0.001) from 7.69 (week 2) to 10.64 kg/day (week 4). Sow HE was constant throughout lactation (686 kJ/kg 0.75 per day) in spite of increased feed intake and milk production. Oxidation of protein constituted 13% of HE in both groups, while oxidation of carbohydrates and fat constituted 84% and 2% for LF sows and 80% and 7% for HF sows, respectively. The present study suggests that the dietary treatments did not affect milk production, milk fat content or the energy mobilisation of the sow. The maintenance requirement of metabolisable energy (ME) amounted to 482 kJ/kg 0.75 per day. It was concluded that the milk production was limited by the energy supply and that the efficiency for utilisation of dietary ME for milk production increased as lactation progressed.

Effects of Dietary Amino Acid Balance on the Response of Dairy Cows to an Increase of Milking Frequency from Twice to Three Times Daily

An experiment was conducted to examine how the response of dairy cows to a change from twice to three times-daily milking is affected by deficiencies in the dietary supplies of three amino acids, His, Met, and Lys. Six cows were used in a 6×6 Latin square with 14-d periods. The three dietary treatments were: grass silage and a cereal-based supplement containing feather meal as the sole protein supplement; the same silage-cereal diet supplying similar amounts of metabolizable and rumen-undegradable protein but with additional amounts of His, Met, and Lys in the form of fish meal; and the fish meal diet with additional metabolizable energy in the form of an additional 2kg/d of sugar beet pulp. Within each of these dietary treatments, the cows were milked twice and three times daily, making a total of six treatments. When cows were given the feather meal diet, even though dietary metabolizable energy was in considerable excess, a deficiency of specific amino acids prevented any increase in milk yield in response to increasing the frequency of milking from twice to three times daily. In contrast, when cows consumed a similar level of excess metabolizable energy and a similar level of rumen-undegradable protein for which the protein was of better amino acid balance (fish meal), the increased frequency of milking led to increased yield of milk and milk protein.

Effect of apparent ileal digestible lysine to energy ratio on performance of finishing pigs at different dietary metabolizable energy levels.

A study with a total of 96 crossbred barrows and gilts fed ad libitum in a body weight range of 56-110 kg was carried out in order to investigate whether the optimum ratio of apparent ileal digestible lysine : energy (ME) depends on the energy density of the diet. Dietary treatments were ratios of 0.34, 0.42, 0.50 and 0.58 g digestible lysine/MJ ME either at an energy density of 13 or 14 MJ ME. Body weight gain as well as feed and ME conversion rate were improved when lysine : ME ratio increased from 0.34 to 0.50, whereby all parameters showed a significant ratio x sex interaction. Feed intake and feed conversion rate were higher at a dietary energy density of 13 MJ ME than at an energy density of 14 MJ ME but energy density did not influence daily growth rate, ME intake and ME conversion rate. Fat area above eye muscle and meat : fat ratio were lower and eye muscle area and lean percentage were higher at a ratio of 0.42 compared with a ratio of 0.34. Daily feed intake, body weight gain, feed conversion rate and parameters of fatness were higher in barrows than in gilts. Conversely, gilts had higher eye muscle area and lean percentage. Optimum ratio for body weight gain, feed and ME conversion rate calculated by exponential regression analysis were 0.42-0.43 in barrows. In gilts, feed and ME conversion rate were optimized at a ratio of 0.53 and 0.54. Because growth showed a linear response to increasing digestible lysine : ME ratios, optimum ratio for daily gain in gilts is considered to be at least 0.58.

강제환우시킨 산란노계에서 생산성 제고를 위한 대사에너지와 단백질 수준의 탐색

본 연구는 대사에너지(ME)와 조단백질(CP) 수준이 강제환우를 실행한 산란노계의 생산성과 난품질에 미치는 영향을 구명하고자 실시하였다. 강제환우를 실시한 66주령의 이사브라운 산란계 432수 ME 3 수준(2,750, 2,800, 2,850 kcal/kg)과 CP 2수준(15, 17%)의 전체 6 종류 실험사료를 급여하였다. 조사항목으로 ME와 CP의 수준에 따른 산란율과 난중, 사료섭취량을 24주간 측정하였으며, 1일 산란양과 사료요구율을 조사하였다. 난품질은 산란시기별로 5, 50%, 산란피크, 피크 후기, 실험 종료시에 각각 Haugh unit과 난황색, 파각강도를 측정하였다. 산란율은 ME 2,800 kcal/kg과 CP 15%를 급여한 처리구에서 다른 처리구에 비하여 현저하게 높았다(P<0.05). 난중은 ME 2,800 kcal/kg을 급여한 닭에서 증가하는 경향을 나타났다. 1일 산란양은 CP 15%와 ME 2,800 kcal/kg을 섭취한 처리구에서 높은 경향을 나타냈다. 사료섭취량은 ME와 CP의 수준이 증가할수록 현저하게 감소하였다 (P<0.05). 난황색은 CP 17%를 급여한 처리구에서 CP 15% 처리구에 비하여 현저히 개선되었으며, CP 17%와 ME 2,800 또는 2,850 kcal/kg 급여구에서 높은 경향을 나타냈다. 파각강도는 CP 15%와 ME 2,800 kcal/kg을 급여한 닭에서 증가하였다. 본 연구의 결과 강제 환우계에서 산란율과 난품질을 극대화 할 수 있는 사료내 최적의 ME와 CP는 15%와 2,800 kcal/kg 수준으로 사료된다. This experiment was conducted to investigate the influence of different levels of metabolizable energy (ME) and crude protein (CP) on post-molt performance and egg quality of spent laying hens. Four hundred and thirty two, ISA Brown hens at sixty six weeks of age after molt induction were fed six experimental diets containing three ME (2,750, 2,800, 2,850 kcal/kg) with two CP (15, 17%) levels in a factorial design. The influence of ME and CP were evaluated on egg production, egg weight and feed intake throughout 24 weeks of production. Egg mass and feed conversion ratio (FCR) were measured during the experimental period. Haugh unit, yolk color and eggshell breaking strength were measured at 5%, 50%, peak, post peak and end stage of egg production. The hens fed 2800 kcal/kg diet along with 15% CP recorded the highest outcome of egg production (P<0.05). The egg weight has been shown to increase with hens receiving 2,800 kcal/kg ME. Daily egg mass tended to increase in hens fed with 15% CP and 2,800 kcal/kg ME. Feed intake decreased significantly with the level of ME and CP in the diet increased (P<0.05). Yolk color was improved significantly in eggs laid by the hens receiving 17% CP than 15% diet. It also tended to be higher in 17% CP with 2,800 or 2,850 kcal/kg ME diet treatments. Egg shell breaking strength increased with hens receiving diets of 15% CP and 2,800 kcal/kg. From this experiment it can be concluded that the ME level of 2,800 kcal/kg coupled with 15% CP could be used to achieve the higher egg production and better eggshell strength in induced molting hens.

Evaluation of Different Energy Feeding Systems With Production Data from Lactating Dairy Cows Offered Grass Silage-Based Diets

A set of data from 838 lactating dairy cows, drawn from 12 long-term feeding studies (at least 8 wk/period), was used to evaluate the energy feeding systems for dairy cows currently adopted in Australia, France, The Netherlands, the United Kingdom, and the United States. The animals were offered mixed diets of concentrates, forage [grass silages (n=33) and corn silages (n=5)] ad libitum. Data used in the present evaluation were either measured [dry matter (DM) intake, milk production and live weight], measured/estimated [dietary metabolizable energy (ME) concentration] or estimated [milk energy output and live weight change (LWC)]. The mean-square prediction error (MSPE) was used for the evaluation. Total ME intake, milk yields, and LWC varied from 91 to 338 MJ/d, 7.7 to 48.9, and −1.23 to 1.73 kg/d, respectively. Australian and French systems predicted total energy requirement and milk yield relatively well, while British, Dutch and American systems underpredicted total energy requirement by proportionately 0.06, 0.04, and 0.03, respectively; and overpredicted milk yield by 0.09, 0.06, and 0.04. The Agricultural and Food Research Council (AFRC) each produced a relatively larger error of the bias (predicted−actual data) over the total MSPE for ME requirement and milk yield and a relatively smaller error of random than other systems. However, an addition of proportionately 0.05 to the total predicted ME requirement of AFRC, as suggested in this system and currently used in the UK, indicated the prediction accuracy of ME requirement and milk yield is similar to Australian and French systems. Nevertheless, all the systems had a poor prediction of LWC. For each system, the total prediction error (total MSPE) was mainly derived from the line (slope; 0.49 to 0.64 of total MSPE), while less derived from the random (0.20 to 0.48 of total MSPE), indicating a large variation between the predicted and actual LWC existed among individual cows. The residual plots of the residual differences in LWC against predicted LWC revealed that the prediction error was greater with increasing LWC. It is concluded that Australian and French systems have a better prediction of total energy requirement and milk yield than other systems, and LWC is an inappropriate indicator of energy balance in lactating dairy cows.

Effect of whole and demucilaged linseed in broiler chicken diets on digesta viscosity, nutrient utilisation and intestinal microflora

1. A study was undertaken to evaluate the effects of the inclusion of linseed or demucilaged linseed in the diet on the performance, fat and fatty acid digestibilities, metabolisability of gross energy and intestinal microflora. 2. The dietary inclusions were 80 and 160 g/kg for linseed and 160 g/kg for demucilaged linseed. Diets were given to chickens from 1 to 23 d of age. 3. Incorporation of linseed in the diet, particularly at 160 g/kg, depressed weight gain and food utilisation. Digestibility of fat and single fatty acids and dietary metabolisable energy were reduced. 4. Inclusion of linseed in the diet markedly increased the viscosity of ileal digesta. Microbial activity in the ileum and caeca was not greatly affected, but there was a significant increase in the number of lactobacilli. 5. The antinutritional effects caused by feeding linseed were partially overcome by substituting demucilaged linseed for linseed in the diet. 6. Results from the current study suggest that the viscous properties of mucilage are a major factor in the observed antinutritional effects of linseed through increasing intestinal viscosity. Such effects might also be mediated by the gut microflora.

The effect of concentrate feed level on the response of lactating dairy cows to a constant proportion of fodder beet inclusion in a grass silage‐based diet

Abstract The effects of level of concentrate supplementation on the response of dairy cows to grass silage‐based diets containing a constant proportion of fodder beet were examined. Forty Holstein‐Friesian dairy cows of mixed parity were used in a 2 × 5 factorial design experiment. Two basal diet types [grass silage alone or grass silage mixed with fodder beet in a 70:30 dry matter (DM) ratio] were offered ad libitum, and the effects of five levels of concentrate supplementation (mean = 3·0, 5·3, 7·5, 9·8 and 12·0 kg DM per cow d−1) were examined. Concentrate supplements were offered via an out‐of‐parlour feeding system. These treatments were examined in a three‐period (period length = 4 weeks) partially balanced changeover design experiment.Fodder beet inclusion had no significant effect on the estimated metabolizable energy (ME) concentration of the ration (P &gt; 0·001). Total DM intake, estimated ME intake, milk yield, milk protein content and milk energy output all showed significant linear increases with increasing level of concentrate inclusion (P &lt; 0·001) while, in addition, milk yield and milk energy output exhibited a significant quadratic increase (P &lt; 0·01). The inclusion of fodder beet in the diet reduced silage DM intake (P &lt; 0·01) but resulted in an increase in total DM intake and estimated ME intake (P &lt; 0·001). However, inclusion of fodder beet had no significant effect on milk yield (P &gt; 0·05), while increasing milk protein content and milk energy output (P ≤ 0·05). Milk energy output, as a proportion of estimated ME intake, was significantly (P &lt; 0·001) reduced by fodder beet inclusion (0·44 vs. 0·38).Despite large increases in estimated ME intake with the inclusion of fodder beet at all levels of concentrate supplementation, milk energy output responses were small, resulting in an overall reduction in the efficiency of conversion of ME intake into milk energy output. An increased partitioning of dietary ME intake to tissue gain is suggested as the most likely explanation for the observations made.

Effect of chromium propionate and metabolizable energy on growth, carcass traits, and pork quality of growing-finishing pigs.

An experiment was conducted to evaluate the dietary effects of Cr propionate (CrProp) and metabolizable energy (ME) on growth, carcass traits, and pork quality of growing-finishing pigs. One hundred forty-four Cambrough-22 barrows were allotted to four dietary treatments in a randomized complete block design (six replicates of six pigs per replicate; average initial and final body weight were 27 and 113 kg, respectively). The dietary treatments were: 1) corn-soybean meal basal (B; low ME), 2) B + 200 ppb of Cr (as CrProp), 3) B + 200 kcal ME/kg (4.5% added fat; high ME), or 4) B + 200 kcal ME/kg + 200 ppb of Cr. At trial termination, three pigs per replicate were killed to determine dietary effects on carcass traits and pork quality. Overall average daily gain, average daily feed intake, and gain:feed ratio were not affected (P > 0.10) by diet. During the early growing period, average daily gain was increased in pigs fed the CrProp-low-ME diets, but decreased in pigs fed the CrProp-high ME diets (Cr x ME, P < 0.04). Feed intake was increased (P < 0.05) in pigs fed the high-ME diets during the early growing period. Forty-five min and 24 h pH were not affected (P > 0.10) by diet. The CIE L* tended (P = 0.07) to be increased and shear force tended (P = 0.06) to be decreased in pigs fed high-ME diets. Subjective marbling was increased (P < 0.03) and longissimus muscle percentage moisture and thaw loss were decreased (P < 0.04) in pigs fed CrProp. Chromium propionate had no consistent effect on growth and carcass traits in this experiment; however, CrProp did affect some aspects of pork quality.

Relationships between dietary fatty acid composition and either melting point or fatty acid profile of adipose tissue in broilers

Data on the fatty acid composition of the diet and that of the adipose tissue in broilers were collected from the literature. The linear regression between the dietary and the adipose tissue unsaturated to saturated fatty acids ratio (U/S ratio) was calculated because the U/S ratio of adipose tissue fat determines its melting point, which is an indicator of the consistency of poultry fat. For 54 data points from three different experiments, the linear correlation coefficient of the relationship between dietary and adipose tissue U/S ratio was 0.77. The regression equation for linoleic acid in adipose tissue as a function of dietary linoleic acid was calculated. The linoleic acid content of adipose tissue was expressed as weight percentage of total fatty acids. Intake was expressed as either weight percentage of total fatty acids or as energy percentage of total dietary metabolizable energy. The linear correlation coefficients were 0.68 and 0.78 as based on 116 or 91 data points from 15 or 12 different experiments. Significant correlations were also found for α-linolenic acid. The linoleic acid content of adipose tissue was found to be correlated ( r=0.87) for 25 data points with that in consumable broiler meat, which may affect serum cholesterol concentrations in humans. With the help of the regression formulas presented it may be possible to formulate broiler diets in relation to consumer health and product quality.

Comparison of two direct bioassays using 3-week-old broilers to measure the metabolisable energy of diets containing cereals high in fibre: Differences between true and apparent metabolisable energy values

1. Nitrogen-corrected apparent and true metabolisable energy contents (AMEN and TMEN) of 12 diets, containing different amounts of maize, wheat, barley and rye, barley with β -glucanase and maize with 0.05 g/kg guar gum were measured using 3-week-old male broilers. 2. The AMEN method involved: 4 d of dietary adaptation, 24 h of starvation, 54 h of ad libitum feeding, 24 h of starvation and daily total droppings collection. TMEN was measured after a 48 h starvation period followed by 2 d of tube-feeding two doses of 15 g of the diets and quantitatively collecting all the droppings after 48 h of starvation. The endogenous energy losses (EELN) were measured after tube-feeding 8 chickens with 30 g of glucose, also over 2 d. 3. The results show that a significant interaction exists between the nature of the diets and the method used to measure metabolisable energy. Differences between TMEN and AMEN values ranged from 1.03 to 1.98 MJ/kg dry matter. These differences were positively correlated with the total pentosan contents of the diet (r = 0.94), the natural logarithm of the viscosities of the water extracts (r = 0.87), the sum of the contents of total pentosans and total β -glucan (r = 0.85), the calculated total non-starch polysaccharide contents (r = 0.79), the neutral detergent fibre contents (r = 0.76) and the total β -glucan contents (r = 0.70). Furthermore, a significant interaction was found between diets and the method used to derive lipid digestibility. The differences between apparent and true lipid digestibility ranged from 0.05 percentage points for the wheat diet to 0.20 percentage points for the rye diet. 4. From the results of this trial, it appears that TMEN overestimates the energy value of high fibre diets.