scholarly journals Live and internal organ weights of male growing pigs fed low protein and low energy diets supplemented with multi-enzyme

2021 ◽  
Vol 47 (6) ◽  
pp. 99-107
Author(s):  
R. A. Amaefule ◽  
D. N. Onunkwo ◽  
O. C. Ilouno ◽  
T. C. Iwuji ◽  
I. P. Ogbuewu ◽  
...  
Keyword(s):  
Crude Protein ◽  
Energy Levels ◽  
White Male ◽  
Live Weight ◽  
Growing Pigs ◽  
Metabolizable Energy ◽  
Low Energy ◽  
Scale Model ◽  
Internal Organs ◽  
Large White

Organ characteristics of male growing male pigs fed low crude protein and low energy diets supplemented with multi-enzyme were determined using 36 hybrid (Landrace x Large white) male pigs of 8-10 weeks old. Two metabolizable energy (3000 and 2600 Kcal ME/kg) and three crude protein levels (14, 16 and 18 % CP) were used to formulate six dietary treatments; T1: control (3000 Kcal ME/kg; 18 % CP), T2 (3000 Kcal ME/Kg; 16 % CP), T3 (3000 Kcal ME/kg; 14 % CP), T4 (2600 Kcal ME/kg; 18 % CP), T5 (2600 Kcal ME/kg; 16 % CP) and T6 (2600 Kcal ME/kg; 14 % CP). The enzyme was added to all the treatments at 1g/kg diet except the control. The treatments were replicated three times with two pigs per replicate. The experiment was a 2 x 3 factorial. The pigs were starved for 12 hours but allowed access to drinking water, stunned and bled completely. It was cut open though the thorax region along the underline to the abdomen, exposing the entire internal organs and GIT contents. The heart, lungs, liver, kidneys, spleen and other internal organs were examined, carefully removed and weighed with a sensitive electronic kitchen scale, model SF-400. Higher (P <0.05) live weight (33500.00g), with lower (P <0.05) mean values for heart and viscera were recorded in male growing pigs fed T4. Male growing pigs fed with T3 and T6 had lower (P<0.05) live weight (12200.00g and 11500.00g), and higher (P<0.05) relative internal organs. Male growing pigs fed 14 % CP diets (T3 and T6) with their corresponding metabolizable energy levels (3000kcal and 2600kcal) recorded higher (P<0.05) heart and viscera's values. Keeping growing (male) pigs on low crude protein diets (14 %) supplemented with multi-enzyme, irrespective of the energy levels, did not improve live weight but increased relative organ weight.   Les caractéristiques des organes de porcs mâles en croissance nourris à faible en protéines brutes et en énergie mais plutôt supplémentée en multi-enzymes ont été déterminées en utilisant 36 porcs mâles hybrides (Landrace x Large white) âgés de 8 à 10 semaines. Deux énergies métabolisables (3000 et 2600 Kcal ME / kg) et trois niveaux de protéines brutes (14, 16 et 18% CP) ont été utilisés pour formuler six traitements diététiques ; T1 : contrôle (3000 Kcal ME / kg ; 18% CP), T2 (3000 Kcal ME / Kg ; 16% CP), T3 (3000 Kcal ME / kg ; 14% CP), T4 (2600 Kcal ME / kg ; 18 % CP), T5 (2600 Kcal ME / kg ; 16% CP) et T6 (2600 Kcal ME / kg ; 14% CP). L'enzyme a été ajoutée à tous les traitements à raison de 1 g / kg de régime sauf le témoin. Les traitements ont été répliqués trois fois avec deux porcs par réplica. L'expérience était une factorielle 2 x 3. Les porcs ont été affamés pendant 12 heures mais ont eu accès à l'eau potable, étourdis et saignaient complètement. Il a été ouvert à travers la région du thorax le long du trait de soulignement jusqu'à l'abdomen, exposant l'ensemble des organes internes et le contenu du 'GIT'. Le cœur, les poumons, le foie, les reins, la rate et d'autres organes internes ont été examinés, soigneusement prélevés et pesés avec une balance de cuisine électronique sensible, modèle SF-400. Un poids vif plus élevé (P <0,05) (33500,00 g), avec des valeurs moyennes plus faibles (P <0,05) pour le cœur et les viscères ont été enregistrés chez des porcs en croissance mâles nourris au T4. Les porcs mâles en croissance nourris avec T3 et T6 avaient des organes internes relatifs inférieurs (P <0,05) (12 200,00 g et 11500,00 g) et supérieurs (P <0,05). Les porcs mâles en croissance nourris avec 14% de régimes 'CP' (T3 et T6) avec leurs niveaux d'énergie métabolisables correspondants (3000 kcal et 2600 kcal) ont enregistré des valeurs cardiaques et viscérales plus élevées (P <0,05). Le fait de garder les porcs en croissance (mâles) avec des régimes pauvres en protéines brutes (14%) supplémentés en multi-enzymes, quels que soient les niveaux d'énergie, n'a pas amélioré le poids vif mais augmenté le poids relatif des organes

The protein and energy nutrition of the pig. V. The effect of varying the protein and energy levels in the ‘finishing diets’ of heavy pigs

1965 ◽  
Vol 65 (3) ◽  
pp. 405-409 ◽  
Author(s):  
D. W. Robinson
Keyword(s):  
Crude Protein ◽  
Energy Levels ◽  
Live Weight ◽  
High Energy ◽  
Feeding Trial ◽  
Large White ◽  
High Energy Level ◽  
Finishing Diets ◽  
Main Effects ◽  
Carcass Measurement

1. A feeding trial was carried out using fortyeight Large White pigs, individually fed in a Danish type piggery. Six different diets prepared at two levels of digestible energy and three levels of crude protein were fed to eight replicates consisting of four hogs and four gilts per replicate. A record was maintained of the weekly live-weight gain and food was given at a defined restricted level in relation to the live weight. Carcass quality was assessed by complete dissection into visible lean, fat and bone etc.2. Of the main effects, energy, supply was without significant effect upon growth, food conversion efficiency (FCE) or any carcass characteristics except body length which was increased with a high energy level. The protein level in the diet had a significant effect upon the percentage of carcass lean and the killing-out percentage, the higher levels of protein increasing both these measurements significantly. Gilts were significantly superior to hogs in every carcass measurement although hogs grew significantly faster.

Determination of the optimum crude protein requirement of pigs in a tropical environment

1972 ◽  
Vol 14 (1) ◽  
pp. 57-67 ◽  
Author(s):  
G. M. Babatunde ◽  
M. J. Olomu ◽  
V. A. Oyenuga
Keyword(s):  
Crude Protein ◽  
Dry Matter ◽  
Nitrogen Retention ◽  
Live Weight ◽  
Growing Pigs ◽  
Tropical Environment ◽  
Protein Requirement ◽  
Large White ◽  
Protein Requirements ◽  
Protein Levels

SUMMARYFeeding trials were carried out at different times of the year to determine the optimum crude protein requirements of weaner and growing pigs, using principally the locally available ingredients. The animals used were 96 weaners and 113 growing pigs of the Large White and Landrace breeds of average initial weights of about 9 kg and 41 kg respectively. Test diets contained protein levels ranging from 12% to 24% on a dry-matter basis, and the pigs were mostly group-fed ad libitum except for one trial. Average daily gains, efficiency of feed utilization, apparent nitrogen retention and digestibility, and feed cost per kg of body gain were measured. In a humid tropical environment, such as Ibadan, the optimum crude protein requirement for weaner pigs from 9 kg to 34 kg live weight is between 22 % and 24 % of dry matter, while that for the fattening pigs from 41 kg to 82 kg live weight is between 18% and 21% of dry matter.

scholarly journals The influence of dietary protein and energy levels on the performance, meat bone ratio and meat chemical composition of SenSi-1 Agrinak chicken

2019 ◽  
Vol 24 (1) ◽  
Author(s):  
Cecep Hidayat ◽  
Sofjan Iskandar
Keyword(s):  
Chemical Composition ◽  
Crude Protein ◽  
Production Efficiency ◽  
Energy Levels ◽  
Live Weight ◽  
Metabolizable Energy ◽  
Meat Production ◽  
Treatment Combination ◽  
Protein Levels ◽  
Dietary Crude Protein

<p class="Default"><span lang="EN-US">Sensi-1 Agrinak is a strain of the improved native chickens for meat production in Indonesia. The objective of </span><span lang="IN">this</span><span lang="EN-US"> study  was to investigate influence of different dietary energy and protein levels on </span><span lang="IN">p</span><span lang="EN-US">erformance, meat bone ratio</span><span lang="IN">,</span><span lang="EN-US"> and meat chemical composition of Sensi-1 Agrinak chicken, reared until 10 weeks of age. Two hundred and sixteen of unsexed day old chickens (DOC) of  Sensi-1 Agrinak were subjected to six experimental rations differed in dietary crude protein (CP) content,. </span><span lang="IN">Namely:</span><span lang="EN-US"> 21;19; and 17 % and dietary  metabolizable  energy (ME) (2800 and 3000 kcal/kg). Each treatment combination was replicated  four times and fed from day old to 10 weeks old. In each treatment combination there were nine unsexed-DOCs. The parameters observed were performance (i.e. live weight, feed intake, viability, FCR), economic index (European Production Efficiency Factor/EPEF), meat bone ratio, and meat chemical composition.  </span><span lang="IN">R</span><span lang="EN-US">esult showed that  </span><span lang="EN-US">increas</span><span lang="IN">ed</span><span lang="EN-US"> of dietary CP level increased live weight and EPEF (p&lt;0.05). Sensi-1 Agrinak chicken had the best FCR (2.59), when fed  diet containing 21% CP and 3000 kcal/kg. Increas</span><span lang="IN">ed</span><span lang="EN-US"> dietary CP level increased the  meat-bone ratio of breast, thighs, and drumsticks. Meanwhile, increas</span><span lang="IN">ed</span><span lang="EN-US"> levels of dietary CP and ME did not affect (p&gt;0.05) meat chemical composition. It </span><span lang="IN">is</span><span lang="EN-US"> concluded that optimal dietary levels of crude protein and energy for unsexed Sensi-1 Agrinak chicken  up to 10 weeks of age were 21% CP and 3000 kcal/kg.</span></p>

Haematological indices of grower pigs fed low protein and low energy diets supplemented with multi-enzyme

2020 ◽  
Vol 47 (1) ◽  
pp. 167-173
Author(s):  
R. A. Amaefule ◽  
I. F. Etuk ◽  
T. C. Iwuji ◽  
I. P. Ogbuewu ◽  
O. H. Obikaonu ◽  
...  
Keyword(s):  
Blood Cell ◽  
White Blood Cell ◽  
Red Blood Cell ◽  
Crude Protein ◽  
Physiological State ◽  
White Male ◽  
Growing Pigs ◽  
Low Energy ◽  
Farm Animals ◽  
Haematological Indices

One of the reliable information for evaluating nutritional status, performance and physiological state of farm animals to nutrient utilization is through haematological indices assessment. Haematological parameters of grower pigs fed low crude protein and low energy diets supplemented with multi-enzyme (enziblend plus+) were determined using 36 hybrid (Landrace x Large white) male pigs of 8-10 weeks old. Two metabolizable energy (3000 and 2600 Kcal ME/kg) and three crude protein levels (18, 16 and 14 % CP) were used to formulate Six dietary treatments; T1 (3000 Kcal ME/Kg; 18 % CP), T2 (3000 Kcal ME/Kg; 16 % CP+ 1g of enzyme/kg diet), T3 (3000 Kcal ME/Kg; 14 % CP+ 1g of enzyme/kg diet), T4 (2600 Kcal ME/Kg; 18 % CP + 1g of enzyme/kg diet), T5 (2600 Kcal ME/Kg; 16 % CP + 1g of enzyme/kg diet) and T6 (2600 Kcal ME/Kg; 14 % CP + 1g of enzyme/kg diet). The treatments were replicated three with two pigs per replicate. The experiment was a 2 x 3 factorial, and T1 served as the control. Blood samples were collected (3mls) via the ear vein from one pig in each replicate, three from treatment for haematological analysis. The results of this study recorded significant differences (P<0.05) in most of the hematological parameters evaluated, except in mean corpuscular haemoglobin concentration (MCHC) and basophile counts of the pigs. Grower pigs fed T2 and T4 diets recorded significantly (P<0.05) higher packed cell volume (PCV) (40.15% and 40.22%), hemoglobin (12.25g/dl and 12.00g/dl), red blood cell (7.95 x106 / µl and 8.00 x106 / µl), white blood cell (8.12 x103 / µl and 7.91 x103 / µl) and lymphocyte counts (5.26 x103 / µl and 5.00 x103 / µl). Grower pigs on T6 recorded significantly (P <0.05) lower mean values for PCV (32.55%), hemoglobin concentration (Hb) (9.82g/dl), red blood cell (RBC) (5.32 x103 / µl), white blood cell (WBC) (6.10 x103 / µl), lymphocyte (3.10 x103 / µl) and monocyte (0.31 x103 / µl) counts, respectively. Based on the findings of this study, feeding of growing pigs with low energy and low crude protein diets below 16 % CP with multi-enzyme supplementation adversely effected PCV, hemoglobin, RBC, WBC, lymphocytes and monocytes of grower pigs and therefore should be avoided in pig production.

Influence of energy intake on protein and lipid deposition in Creole and Large White growing pigs in a humid tropical climate

2006 ◽  
Vol 82 (6) ◽  
pp. 937-945 ◽  
Author(s):  
D. Renaudeau ◽  
B. Bocage ◽  
J. Noblet
Keyword(s):  
Average Daily Gain ◽  
Live Weight ◽  
Climatic Conditions ◽  
Growing Pigs ◽  
Metabolizable Energy ◽  
Lipid Deposition ◽  
Large White ◽  
Feeding Level ◽  
Dietary Nutrients ◽  
Caribbean Area

AbstractTwenty-four castrated males were used to study the effect of breed (Large White v. Creole (LW v. CR)) and feeding level (0·70, 0·80, 0·90, and 1·00 ad libitum) on growth performance and protein deposition (PD) and lipid deposition (LD) between 30 and 60 kg in growing pigs under tropical climatic conditions; the CR pigs are raised in the Caribbean area and can be qualified as fat and slow growing pigs. Daily protein and amino acids supplies were calculated to be non-limiting for protein gain. Total PD and LD were measured according to the comparative slaughter technique. Digestibility coefficients of energy and nutrients were estimated over a 10-day period at 45 kg live weight. Neither the breed nor the feeding level influenced the apparent digestibility coefficients of dietary nutrients; only energy digestibility was increased at reduced feeding levels (P<0·05). Average daily gain increased linearly with the increase of metabolizable energy (ME) intake and the slope of the relationship was lower in CR than in LW pigs (30·4 v. 36·6 g per additional MJ ME). The food conversion ratio was not affected by feeding level but it was significantly higher in CR than in LW pigs (2·88 v. 2·36 kg /kg; P<0·001). Daily PD increased with ME intake according to a linear relationship in both breeds and the slope was significantly affected by breed (3·1 v. 4·2 g/MJ ME in CR and LW pigs, respectively; P<0·001). In contrast, the increase of LD and total energy retained with ME were higher in CR than in LW pigs (8·4 v. 6·4 g/MJ and 0·40 v. 0·36 MJ/ MJ ME, respectively; P<0·001).

Effect of phytase supplementation with two levels of phosphorus diets on ileal and faecal digestibilities of nutrients and phosphorus, calcium, nitrogen and energy balances in growing pigs

2005 ◽  
Vol 81 (1) ◽  
pp. 67-75 ◽  
Author(s):  
M. Z. Fan ◽  
T. J. Li ◽  
Y. L. Yin ◽  
R. J. Fang ◽  
Z. Y. Tang ◽  
...  
Keyword(s):  
Live Weight ◽  
Basal Diet ◽  
Growing Pigs ◽  
Metabolizable Energy ◽  
Energy Output ◽  
Energy Concentration ◽  
Total Output ◽  
Large White ◽  
Ileal Digestibility ◽  
Energy Balances

AbstractThe experiment was conducted to assess the effects of phytase supplementation to diets with two levels of phosphorus (P) on ileal and faecal digestibility of nutrients and phosphorus, calcium, nitrogen and energy balances in growing pigs. Fifteen Landrace × Large White × Chinese Black barrows, with an initial live weight of 22·2 kg fitted with a simple T-cannula at the distal ileum, were randomly allocated to one of the five diet treatments, according to a of cross-over design with two periods. The basal diet was typical of southern Asia with maize/rice and rapeseed/cottonseed meals. A normal (NP, supplemented with 4·8 g/kg of CaHPO4) and a low-P diet (LP, not supplemented with CaHPO4) were formulated. Both of the diets were supplemented with and without Natuphos® Phytase (500 phytase units (FTU) per kg diet). An enzyme hydrolysed casein (EHC) diet (diet 5) was also formulated to determine the flow of the ileal endogenous amino acids (AA). The results showed that both the higher level P treatment and phytase supplementation increased (P < 0·05) the apparent ileal digestibility (AID) of dry matter (DM), organic matter (OM), crude protein (CP) and energy. Phytase supplementation also increased (P < 0·05) the AID of Ca and P. Pigs given the higher level of P or the phytase diet increased apparent faecal digestibility (AFD) of DM, OM and energy. Phytase supplementation reduced (P < 0·01) faecal Ca output and increased (P < 0·05) proportional Ca retention. The higher level of P increased (P < 0·001) total P intake and P retention (P < 0·05) but did not affect the proportion of P retained (P > 0·05). Phytase supplementation did not affect P balance (P > 0·05). Pigs given the higher level P or the phytase diet had reduced (P < 0·05) faecal energy concentration, although there was no affect on urine energy output, digestible energy (DE) and metabolizable energy (ME). However, there were P × phytase effects on DE and ME (P < 0·05). There were no P × phytase effects (P > 0·05) on AID of AA except with isoleucine (P < 0·01). Phytase supplementation increased (P < 0·05) AID of histidine, isoleucine, threonine and glutamine and there was a numeric increase in AID for most of the other AA. There was P × phytase effect on AFD of histidine (P < 0·05), isoleucine (P < 0·05), methionine (P < 0·05) and threonine (P < 0·01). Phytase supplementation increased the AFD of isoleucine (P < 0·05), threonine (P < 0·01) and tended to increase AFD of tyrosine (P < 0·05). The level of MCP affected the AFD of lysine (P < 0·01), threonine (P < 0·05), aspartic acid (P < 0·05). Phytase supplementation increased true ileal digestibility of histidine (P < 0·05), isoleucine (P < 0·001), threonine (P = 0·001), glutamine (P < 0·01), respectively. These results indicate that phytase used in the present study was able to improve the utilization of DM, OM, CP, Ca, P, energy and amino acid in a maize/rice and rapeseed/cottonseed meal based diet and reduce total output of them in manure.

Lactational oestrus in the sow 4. Variation in the incidence and timing of lactational oestrus in groups of sows

1983 ◽  
Vol 36 (3) ◽  
pp. 453-460 ◽  
Author(s):  
M. J. Bryant ◽  
G. Palmer ◽  
D. J. Petherick ◽  
P. Rowlinson
Keyword(s):  
Regression Analysis ◽  
Crude Protein ◽  
Post Partum ◽  
White Male ◽  
Live Weight ◽  
Hybrid Female ◽  
Large White ◽  
Independent Variables ◽  
Ad Libitum

ABSTRACTEighty multiparous Camborough hybrid female pigs (sows) and their litters, on average 15 days post partum, were housed in groups of five in multi-accommodation pens. The sows were fed ad libitum on a proprietary diet containing 160 g crude protein per kg from grouping to 30 days post partum, when they were fed to scale twice daily in individual feeders until weaning at 42 days post partum. One of four Large White male pigs (boars) was introduced to each group on the day following grouping, each boar being run with four groups.Oestrus occurred in 62 sows, on average 10·2 ± 3·3 days after grouping. The differences between groups in the interval from grouping and boar introduction to the onset of oestrus were statistically significant (P < 0·01). Neither the incidence nor the timing of oestrus could be related to the identity of the boar.Regression analysis revealed relationships between a number of independent variables and the incidence and timing of lactational oestrus. Sows which gained more live weight from farrowing to weaning and whose litters consumed more creep food were more likely to show lactational oestrus. Sows were slower to show lactational oestrus when they gained little weight from farrowing to weaning, had lower live weights at weaning and gained less weight from the previous weaning, despite eating comparatively more food during grouping. The sows which took longer to show lactational oestrus also had heavier piglets at grouping and more piglets in their litters at weaning. The difficulties arising in the interpretation of these results are discussed.

Dietary protein content and the subsequent body composition and food intake of pigs

1978 ◽  
Vol 90 (1) ◽  
pp. 69-76 ◽  
Author(s):  
D. Wyllie ◽  
J. B. Owen
Keyword(s):  
Food Intake ◽  
Crude Protein ◽  
Live Weight ◽  
Growing Pigs ◽  
Protein Diet ◽  
Food Conversion ◽  
Lean Tissue ◽  
Large White ◽  
Lower Protein ◽  
Daily Gain

SUMMARYForty Large White × Wessex pigs were fed from 7 to 27 kg live weight, on diets containing either 28 or 14% crude protein. From 27 to 113 kg live weight the pigs were fed a common diet ad libitum. Pigs from each treatment were killed at 27, 54, 82 and 113 kg live weight and the chemical composition was determined. From 7 to 27 kg and from 27 to 113 kg live weight, daily gain, food intake and food conversion efficiency were similar for the two treatments.At 27 kg, pigs on the lower protein diet were fatter and contained less lean tissue. Between 27 and 54 kg live weight the pigs previously on the higher protein diet deposited a much greater amount of fat than the pigs on the lower protein diet, so that by 54 kg the pigs initially on the lower protein contained less fat. At 82 and 113 kg live weight the pigs given the lower protein diet initially also tended to contain less fat. These findings are discussed with particular reference to the voluntary energy intake of growing pigs.

Responses to variations in dietary energy intakes by growing pigs 3. Effect of level of intake of diets of differing protein and fat content on the performance of growing pigs

1972 ◽  
Vol 15 (2) ◽  
pp. 127-137 ◽  
Author(s):  
J. L. Davies ◽  
I. A. M. Lucas
Keyword(s):  
Crude Protein ◽  
Agricultural Research ◽  
Energy Levels ◽  
Daily Intake ◽  
Live Weight ◽  
Growing Pigs ◽  
Feed Conversion ◽  
Agricultural Research Council ◽  
Daily Allowance ◽  
Four Levels

SUMMARYThree diets were given separately, each at four levels of digestible energy (DE) intake, to gilts, castrates and boars growing from 21 to 92 kg live weight. The energy levels were those suggested by the Agricultural Research Council, compared with a 5% increase or 10% or 20% decreases in daily allowance. One diet (ME 18) had 3·0 Meal DE/kg and 18·2% crude protein; the other two (HE 16 and HE 19) had 3·26 Meal DE/kg and 16·1% or 19·3% crude protein.They were given unchanged throughout the experiment. Responses to change in daily DE intake were not affected by sex or diet, except in shoulder fat thickness. Feed eaten per kg gain did not vary by more than 4% over the intake levels investigated, and no difference was significant. On average, each reduction in daily intake below the ARC+5% allowance led to an increase of 1·2 percentage units of carcass lean and a decrease of 1·3 percentage units of carcass fat.In comparison with HE 16, the higher protein diet HE 19 gave improved feed conversion efficiency and growth rate, particularly in gilts. It did not cause significant changes in carcass measurements. In comparison with ME 18, HE 19 gave more efficient conversion of DE to weight gain, and faster growth.Boars required less feed per kg gain and had faster growth rates and leaner carcasses than gilts, which were superior to castrates. There was a high incidence of unpleasant odour in fat from boars, but some was also detected in that from gilts and castrates.

Influence of energy and protein concentration in the diet on the performance of growing pigs 3. Response to differences in levels of both energy and protein

1972 ◽  
Vol 14 (2) ◽  
pp. 219-228 ◽  
Author(s):  
R. Cooke ◽  
G. A. Lodge ◽  
D. Lewis
Keyword(s):  
Dietary Protein ◽  
Energy Levels ◽  
Live Weight ◽  
Linear Increase ◽  
Growing Pigs ◽  
Percentage Increase ◽  
Feed Conversion ◽  
Fat Percentage ◽  
Large White ◽  
Protein Levels

SUMMARYOne hundred and twenty eight gilts by Landrace sires out of Large White × Landrace females were allocated on the basis of litter relation-ship and initial weight to 16 treatments involving the individual feeding of four dietary protein levels (approximately 15%, 18%, 21% and 24% CP) at each of four energy levels (2830, 3100, 3375 and 3585 kcal DE/kg air-dry feed). Amino acid balance (as% of total CP) was maintained relatively constant, using synthetic lysine and methionine where necessary. Growth performance was measured over a live-weight range of 23 kg to 59 kg, at which latter weight the pigs were slaughtered for carcass evaluation by dissection of the middle ‘joint’ from a half carcass. Linear carcass measure-ments were also taken. There was a significant energy × protein interaction only for killing-out percentage; for all other measures the main effects could be assessed independently. Increase in dietary energy value gave linear increase in growth rate (GR) and improve-ment in efficiency of feed conversion (EFC), accompanied by linear decrease in lean percentage and increase in fat percentage. Increase in dietary protein level gave an increase in GR and improvement in EFC with the first increment (from 15% to 18% CP), but depressions in both these characteristics with the final increment (from 21% to 24% CP). Lean percentage increased and fat percentage decreased with the first protein increment, with no further significant changes. Calculation of daily rates of tissue deposition indicated that maximum rate and efficiency of fat-free carcass gain could be attained with the second lowest energy and protein levels tested (i.e. 3106 kcal DE/kg and 18·2% CP).

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