The effects of wilting of grass prior to ensiling on the response to bacterial inoculation. 1. Silage fermentation and nutrient utilization over three harvests

1996 ◽  
Vol 62 (3) ◽  
pp. 405-417 ◽  
Author(s):  
T. Yan ◽  
D. C. Patterson ◽  
F. J. Gordon ◽  
M. G. Porter
Keyword(s):  
Heat Production ◽  
Nutrient Utilization ◽  
Period Change ◽  
Metabolizable Energy ◽  
Energy Utilization ◽  
Energy Output ◽  
Apparent Digestibility ◽  
Total N ◽  
Silage Fermentation ◽  
The Mean

AbstractFour silages were prepared from perennial ryegrass swards at each of first (primary growth), second (first regrowth) and third (second regrowth) harvests during the 1993 growing season. At each harvest the four silages included two unwilted (without and with inoculant at 2·4 l/t) and two wilted (without and with inoculant at 24 l/t). The four silages within a single harvest, were offered as the total diet at maintenance levels to 12 wether sheep for 3 weeks to determine nutrient apparent digestibilities. They were also given to 12 lactating dairy coivs together with a concentrate supplement, in a three-period change-over study with experimental periods of 8-weeks duration, to examine dry matter (DM) apparent digestibility and utilization of nitrogen (N) and energy in the diets.Inoculation tended to improve silage fermentation with on average lower pH and ammonia-N/total-N across the three harvests, while wilting of grass prior to ensiling significantly increased silage pH fP < 0·001) and ammonia-N/total-N (P < 0·001). Neither inoculation nor wilting had any significant effect on mean nutrient apparent digestibilities, assessed through sheep, across the three harvests. However, at the second harvest inoculation significantly reduced apparent digestibilities of DM (P < 0·001) and N (P < 0·001). At this harvest, wilting also significantly decreased apparent digestibilities of DM (P<0·05) and N (P <0·01), but significantly increased apparent digestibilities of DM (P < 0·05), energy (P < 0·001) and N (F < 0·05) at the third harvest. When the silages were offered as mixed diets to dairy cattle, neither inoculation nor wilting had significant effects on digestibilities of DM, N and energy at any of the three harvests, except for wilting which significantly decreased DM apparent digestibilities (P < 0·05) at the second harvest. However, the mean apparent digestibilities of DM (P < 0·01), N (P < 0·05) and energy (P < 0·01) across the three harvests were significantly lower following wilting, and N apparent digestibility (P < 0·05) was significantly higher following inoculation. The calorimetric data indicated that inoculaton had no significant effects on either methane energy output or heat production. Wilting also had no significant effect on methane energy output, but significantly increased daily heat production (P<0·05) at the first harvest. The efficiencies of metabolizable energy utilization for lactation (k1) were similar between the four silages at each of the first and second harvests, with the average being 0·50. The results of the present study indicated that inoculation tended to improve silage fermentation and significantly increased mean N apparent digestibility of mixed diets across the three harvests, while wilting significantly reduced mean DM, N and energy apparent digestibilities of mixed diets. Neither inoculation nor wilting had significant effects on Rvalue.

The effect of genetic merit and concentrate proportion in the diet on nutrient utilization by lactating dairy cows

1999 ◽  
Vol 132 (4) ◽  
pp. 483-490 ◽  
Author(s):  
C. P. FERRIS ◽  
F. J. GORDON ◽  
D. C. PATTERSON ◽  
M. G. PORTER ◽  
T. YAN
Keyword(s):  
Dairy Cows ◽  
Energy Intake ◽  
Milk Production ◽  
Milk Fat ◽  
Nutrient Utilization ◽  
Metabolizable Energy ◽  
Energy Utilization ◽  
Energy Output ◽  
Genetic Merit ◽  
Gross Energy

Sixty Holstein/Friesian dairy cows, 28 of high genetic merit and 32 of medium genetic merit, were used in a continuous design, 2 (cow genotypes)×4 (concentrate proportion in diet) factorial experiment. High and medium merit animals had Predicted Transmitting Abilities for milk fat plus protein yield, calculated using 1995 as the base year (PTA95 fat plus protein), of 43·3 kg and 1·0 kg respectively. Concentrate proportions in the diet were 0·37, 0·48, 0·59 and 0·70 of total dry matter (DM), with the remainder of the diet being grass silage. During this milk production trial, 24 of these animals, 12 from each genetic merit, representing three animals from each concentrate treatment, were subject to ration digestibility, and nitrogen and energy utilization studies. In addition, the efficiency of energy utilization during the milk production trial was calculated.There were no genotype×concentrate level interactions for any of the variables measured (P>0·05). Neither genetic merit nor concentrate proportion in the diet influenced the digestibility of either the DM or energy components of the ration (P>0·05). When expressed as a proportion of nitrogen intake, medium merit cows exhibited a higher urinary nitrogen output and a lower milk nitrogen output than the high merit cows. Methane energy output, when expressed as a proportion of gross energy intake, was higher for the medium than high merit cows (P<0·05), while urinary energy output tended to decrease with increasing proportion of concentrate in the diet (P<0·05). In the calorimetric studies, neither heat energy production, milk energy output and energy retained, when expressed as a proportion of metabolizable energy intake, nor the efficiency of lactation (kl), were affected by either cow genotype or concentrate proportion in the diet (P>0·05). However when kl was calculated using the production data from the milk production trial the high merit cows were found to have significantly higher kl values than the medium merit cows (0·64 v. 0·59, P<0·05) while k l tended to fall with increasing proportion of concentrate in the ration (P<0·05). However in view of the many assumptions which were used in these latter calculations, a cautious interpretation is required.

The effect of crop maturity on the nutritional value of maize silage for lactating dairy cows. 1. Energy and nitrogen utilization

2000 ◽  
Vol 71 (2) ◽  
pp. 381-390 ◽  
Author(s):  
S. B. Cammell ◽  
J. D. Sutton ◽  
D. E. Beever ◽  
D. J. Humphries ◽  
R. H. Phipps
Keyword(s):  
Starch Content ◽  
Metabolizable Energy ◽  
Energy Utilization ◽  
Energy Output ◽  
Apparent Digestibility ◽  
Maize Silage ◽  
Forage Maize ◽  
Mean Values ◽  
Grass Silage ◽  
Crop Maturity

AbstractFour multiparous Holstein-Friesian cows fitted with simple cannulas in the proximal duodenum and the rumen were offered four diets in a 4 ✕ 4 Latin-square design to evaluate the effect on energy and nitrogen balance of crop maturity of maize when offered as ensiled food with grass silage and a concentrate. Forage maize (cv. Hudson) was ensiled at target dry matter (DM) contents of 230, 280, 330 and 380 g per kg fresh weight (FW). The mean values for volatile corrected DM (VCDM) and starch content of the maize forages as given were 226, 278, 319 and 357 g/kg FW and 180, 263, 327 and 401 g/kg VCDM respectively. Grass silage (GS) containing 247 g VCDM per kg FW was produced from the primary growth of a perennial ryegrass sward. The diets comprised 8·7 kg DM concentrate per day with one of four forage treatments offered ad libitum, in a 3 : 1 DM ratio of maize silage with GS, designated T23, T28, T33 and T38. Each period was of 6 weeks with energy and nitrogen balances conducted in respiration chambers over 6 days in either week 5 or 6. There were no significant effects of maturity on DM intake. Changes in milk yield and composition were not significant but milk protein yield increased significantly (P < 0·05) with maize maturity up to T33 and was linearly related (P < 0·05) to changes in maize silage starch and neutraland acid-detergent fibre (NDF, ADF) content. Total starch intake increased significantly (P < 0·01) with maturity but apparent digestibility of starch was significantly (P < 0·05) reduced only with the most mature maize silage (T38). NDF and ADF intake and amounts digested were not significantly different despite a numerical decline with stage of maturity. Total nitrogen intake and apparent digestibility were not significantly different although there were significant differences (P < 0·05) in the amount of nitrogen excreted as urine, which was greatest on T23 and least on T33, and milk which was least on T23 and greatest on T33. Mean gross energy (GE) intake increased by 17 MJ/day from T23 to T33 but the differences were non-significant. Faecal energy output on T23 was significantly lower (P < 0·05) than the other treatments whilst urine energy on T23 was significantly higher (P < 0·05) compared with T33. Methane energy losses were not significantly different. There were no significant differences between treatments in either GE digestibility or metabolizability, digestible or metabolizable energy (ME) intakes or in the partition of ME to heat, tissue or milk. The calculated ME concentrations of the maize silages were not significantly different with an overall mean of 12·3 MJ/kg VCDM estimated at maintenance intake, or 0·63 MJ/MJ GE. Changes in maize silage composition resulted in a doubling of the ratio of digested starch to digested NDF (0·66, 0·94, 1·10 and 1·21) for treatments T23 to T38 respectively. Despite this large change in digested nutrients no differences in the efficiency of energy utilization were detected.

Effect of forage digestibility and type of concentrate on nutrient utilization by lactating dairy cattle

1995 ◽  
Vol 62 (1) ◽  
pp. 15-27 ◽  
Author(s):  
Frederick J. Gordon ◽  
Michael G. Porter ◽  
C. Sinclair Mayne ◽  
Edmund F. Unsworth ◽  
David J. Kilpatrick
Keyword(s):  
Dairy Cows ◽  
Heat Production ◽  
Nutrient Utilization ◽  
Metabolizable Energy ◽  
Energy Utilization ◽  
Grass Silage ◽  
Forage Digestibility ◽  
Lactating Dairy Cows ◽  
High Fibre ◽  
High Starch

SummarySix lactating dairy cows were used in a three period, part balanced changeover design experiment to investigate the effects of forage digestibility and concentrate composition on the efficiency of nutrient utilization in lactating dairy cows. Six treatments comprising three forage regimens and two concentrate types (starch υ. fibre) were examined in a 3 × 2 factorial design. The three forage regimens were high digestibility grass silage offered ad lib. (HA) or restricted to 6·5 kg dry matter/d (HR) and a low digestibility grass silage offered ad lib. (LA). Within each forage regimen animals were offered 10 kg·d of supplements containing either high-starch or high-fibre concentrations. Experimental periods lasted 28 d with a 10 d recording period, during which animal performance, ration digestibility and nitrogen and energy utilization were measured. Respiratory exchange measurements were made over a 72 h period using indirect open-circuit calorimetry. Throughout the experiment, there were no significant forage × concentrate interactions in any of the intake, production or nutrient utilization results. Milk yield was significantly influenced by forage regimen (24·1, 21·7 and 21·9 kg/d for HA, HR and LA respectively) and concentrate type (21·6 and 23·5 kg/d for high-starch and high-fibre respectively). Concentrate type also significantly influenced milk protein concentration (32·8 and 30·9 g/kg for high-starch and high-fibre respectively). Forage regimen significantly influenced the efficiency of utilization of metabolizable energy (ME) for milk production (κ1) with values of 0·62, 0·64 and 0·59 for HA, HR and LA respectively. Concentrate type had no significant effect on ME intake, heat production or κ1, although animals receiving the high-fibre concentrates synthesized proportionately 0·11 more milk energy per unit of available energy (ME intake – heat production) than those receiving the high-starch concentrates. Interpolation of the values obtained with the two high digestibility forage regimens indicated that at similar ME intakes there was a trend towards a higher κ1 with the diet based on high digestibility silage, and this was in line with the higher metabolizability of the overall diet with this silage.

Effects of ensilage of grass on performance and nutrient utilization by dairy cattle 2. Nutrient metabolism and rumen fermentation

1995 ◽  
Vol 60 (3) ◽  
pp. 347-359 ◽  
Author(s):  
A. Cushnahan ◽  
C. S. Mayne ◽  
E. F. Unsworth
Keyword(s):  
Dairy Cows ◽  
Nutrient Utilization ◽  
Rumen Fermentation ◽  
Metabolizable Energy ◽  
Energy Utilization ◽  
Nutrient Metabolism ◽  
Rumen Degradation ◽  
Lactating Dairy Cows ◽  
Silage Fermentation ◽  
Urinary Nitrogen

AbstractA study was carried out to examine the effects of ensiling and pattern of silage fermentation on nitrogen and energy utilization, rumen fermentation and rumen degradation characteristics of forage by lactating dairy cows. Six nonfistulated dairy cows and three rumen fistulated dairy cows were offered fresh grass (G) or grass silage produced from the same sward which had undergone either an extensive (E) or restricted (R) fermentation. Animals offered extensively fermented silage had liigher urinary nitrogen (N) outputs (expressed as a proportion of N intake) than those offered fresh grass (P < 0·05). Corresponding values for animals offered restricted fermented silage were intermediate between those offered grass and extensively fermented silage. Animals offered fresh grass and restricted fermented silage also had higher methane energy losses (P < 0·05), than those offered extensively fermented silage. The ensiling of grass had little effect on metabolizable energy (ME) intake or on the efficiency of utilization of ME for lactation (k1). Animals offered extensively fermented silage had higher proportions of propionate and lower proportions of acetate than those offered fresh grass or restricted fermented silage (P < 0·001). Ensiling resulted in an increase in the soluble (a) fraction and a reduction in the potentially degradable (b) fraction of N.

Effect of oat particle size on energy and nutrient utilization in growing pigs

2021 ◽  
Author(s):  
Bonjin Koo ◽  
Charles Martin Nyachoti
Keyword(s):  
Particle Size ◽  
Heat Production ◽  
Energy Content ◽  
Geometric Mean ◽  
Nutrient Utilization ◽  
Growing Pigs ◽  
Metabolizable Energy ◽  
Neutral Detergent Fiber ◽  
Energy Utilization ◽  
Experimental Unit

Abstract An experiment was conducted to determine the energy content of oats and to investigate the effects of oat particle size on nutrient and energy balance in growing pigs. Eighteen barrows (23.56 ± 0.94 kg initial body weight) were randomly assigned to one of three dietary treatments with six replicates per treatment. Whole oats were ground with a hammermill fitted with 4.8-mm and 3.2-mm screens to make coarse and medium particle size oats, respectively. Medium oats were further ground with rotary steel cutting grinder fitted with a 2.0-mm screen, and the further ground oats were mixed with medium oats in a 1:3 ratio to make fine oats. Three experimental diets consisted of 96.3% of the coarse, medium or fine oats as a sole source of energy were used. Pigs were fed diets for 16 d, including 10 d for adaptation and 6 d for total fecal and urine collection. Pigs were then moved into indirect calorimetry chambers to determine 24-h heat production and 12-h fasting heat production. All data were analyzed using the MIXED procedure of SAS with the individual pig as the experimental unit. The geometric mean particle sizes for coarse, medium, and fine oats were 765 μm, 619 μm, and 569 μm, respectively. Pigs fed the medium oats diet tended to have (P &lt; 0.10) greater apparent total tract digestibility (ATTD) of starch, neutral detergent fiber, and gross energy than those fed coarse oats diet. The medium oats diet contained greater (P &lt; 0.05) digestible energy (DE), metabolizable energy (ME), and net energy (NE) than the coarse oats diet. Pigs fed the fine oats diet had lower (P &lt; 0.05) ATTD of Ca and P than those fed the coarse oats diet. The DE, ME, and NE contents of fine oats were comparable with those of coarse oats. The determined NE contents for coarse, medium, and fine oats were 2,335, 2,615, and 2,521 kcal/kg on a dry matter basis, respectively. The NE content in medium oats was greater (P &lt; 0.05) than the NE values predicted using published equations. In conclusion, it was suggested to grind whole oats for 619 μm concerning energy utilization. Further grinding to 569 μm reduces Ca and P digestibility.

Energy content of intact and heat-treated dry extruded-expelled soybean meal fed to growing pigs

2021 ◽  
Author(s):  
Bonjin Koo ◽  
Olumide Adeshakin ◽  
Charles Martin Nyachoti
Keyword(s):  
Heat Production ◽  
Soybean Meal ◽  
Energy Content ◽  
Basal Diet ◽  
Growing Pigs ◽  
Metabolizable Energy ◽  
Energy Utilization ◽  
Experimental Unit ◽  
Net Energy ◽  
Heat Treated

Abstract An experiment was performed to evaluate the energy content of extruded-expelled soybean meal (EESBM) and the effects of heat treatment on energy utilization in growing pigs. Eighteen growing barrows (18.03 ± 0.61 kg initial body weight) were individually housed in metabolism crates and randomly allotted to one of three dietary treatments (six replicates/treatment). The three experimental diets were: a corn-soybean meal-based basal diet and two test diets with simple substitution of a basal diet with intact EESBM or heat-treated EESBM (heat-EESBM) at a 7:3 ratio. Intact EESBM was autoclaved at 121°C for 60 min to make heat-treated EESBM. Pigs were fed the experimental diets for 16 d, including 10 d for adaptation and 6 d for total collection of feces and urine. Pigs were then moved into indirect calorimetry chambers to determine 24-h heat production and 12-h fasting heat production. The energy content of EESBM was calculated using the difference method. Data were analyzed using the Mixed procedure of SAS with the individual pig as the experimental unit. Pigs fed heat-EESBM diets showed lower (P &lt; 0.05) apparent total tract digestibility of dry matter (DM), gross energy, and nitrogen than those fed intact EESBM. A trend (P ≤ 0.10) was observed for greater heat increments in pigs fed intact EESBM than those fed heat-EESBM. This resulted in intact EESBM having greater (P &lt; 0.05) digestible energy (DE) and metabolizable energy (ME) contents than heat-EESBM. However, no difference was observed in net energy (NE) contents between intact EESBM and heat-EESBM, showing a tendency (P ≤ 0.10) toward an increase in NE/ME efficiency in heat-EESBM, but comparable NE contents between intact and heat-EESBM. In conclusion, respective values of DE, ME, and NE are 4,591 kcal/kg, 4,099 kcal/kg, and 3,189 kcal/kg in intact EESBM on a DM basis. It is recommended to use NE values of feedstuffs that are exposed to heat for accurate diet formulation.

Energy exchanges of pregnant and lactating ewes

1964 ◽  
Vol 15 (1) ◽  
pp. 127 ◽  
Author(s):  
N McCGraham
Keyword(s):  
Heat Production ◽  
Nitrogen Loss ◽  
Metabolizable Energy ◽  
Energy Utilization ◽  
Carbon And Nitrogen ◽  
Direct Measurements ◽  
Heat Increment ◽  
Energy Retention ◽  
Energy Exchanges ◽  
Pregnant Ewe

At intervals throughout gestation, the energy, carbon, and nitrogen exchanges of four Merino ewes were determined with the aid of closed-circuit indirect calorimetry. Six similar but non-pregnant animals were studied at the same time. The food consisted of equal parts of lucerne and wheaten hay; half the sheep in each group were given a constant 600 g/day and half 900 g/day, and the non-pregnant ewes were fasted on one occasion. Free fatty acids, glucose, and ketones in the blood were also determined during the final stages of pregnancy. Balance measurements were continued during lactation, the ewes being given 1200 g food/day for the first month and 900 g for the second. The digestibility of the food was not affected by pregnancy or lactation, but urinary nitrogen loss decreased as pregnancy advanced and was least during lactation. Although a constant amount of food was eaten, the heat production of each pregnant animal increased throughout gestation. The heat increment of pregnancy at term was 90 kca1/24 hr/kg foetal tissue. The most direct measurements of oxygen uptake by the foetus in utero indicate much lower levels of heat production per kilogram of tissue; it is concluded that these are underestimates. The metabolic rate was unusually high immediately before parturition, and in two cases decreased to near non-pregnant levels 24 hr after lambing. The total energy retention of the ewes became smaller as pregnancy advanced, and in two cases was negative at term. Metabolizable energy was used for reproduction with a gross efficiency of 15–22% and a net efficiency of 13%. The metabolizable energy used per kilogram of foetus was approximately 10% of the maintenance requirement of the ewe herself. Daily energy utilization by the conceptus at term probably accounted for 70% of the glucogenic substances available from the food. There was no evidence of increased gluconeogenesis from protein by the pregnant ewe. The nutrition of the ewe during gestation affected lactation mainly in the first week or two. The data indicate that nitrogen intake rather than energy intake limited milk production. Irrespective of the amount of energy in the milk, the heat increment due to feeding was 20% smaller for lactating than for dry fatteningewes. It is suggested that efficient use of acetate by the mammary gland permits more efficient lipogenesis by other tissues.

An examination of energy utilization in lactating dairy cows receiving a total mixed ration based on maize silage

2000 ◽  
Vol 71 (3) ◽  
pp. 585-596 ◽  
Author(s):  
S. B. Cammell ◽  
D. E. Beever ◽  
J. D. Sutton ◽  
J. France ◽  
the late G. Alderman ◽  
...  
Keyword(s):  
Mean Value ◽  
Open Circuit ◽  
Metabolizable Energy ◽  
Energy Utilization ◽  
Repeated Measure ◽  
Maize Silage ◽  
Individual Values ◽  
Total Mixed Ration ◽  
Stage Of Lactation ◽  
The Mean

AbstractSix multiparous Holstein-Friesian cows were offered a total mixed ration based on maize silage in a repeated measure design to evaluate the partition of gross energy (GE) during early to mid lactation. Four measurements were made at 6-week intervals with energy and nitrogen balances carried out in open-circuit respiration chambers over 6 days during lactation weeks 6, 12, 18 and 24. The intakes of total diet dry matter (DM) corrected for volatile losses (VCDM), organic matter (OM) and GE declined significantly (P< 0•01) as lactation progressed, although apparent digestibility of these fractions was not altered, resulting in a significant (P< 0•01) decline in digestible nutrient intake at each stage of lactation. Methane and urine energy losses were not significantly affected, resulting in significantly (P< 0·001) higher amounts of digestible energy (DE) partitioned to methane and urine as lactation progressed with associated significant reductions in metabolizable energy (ME) intake (MEI) (P< 0·01) and ME as a proportion of DE (P< 0·001) and GE (q) (P< 0·05). With advancing lactation there was a significant (P< 0·001) increase in the amount of ME partitioned to heat (HP/MEI), but no significant change in the amount partitioned to milk and tissue. Individual values for diet metabolizability (ME/GE) at actual (production) levels (qa) (mean 0·625 MJ/MJ) were corrected to an equivalent value at maintenance (qmc) (mean 0·666 MJ/MJ). The overall ME intakes (MJ/day) were: ad libitum, 246, corrected for level of feeding effect, 263, with a predicted ME requirement according to AFRC (1993) (MER93) of 242. Substitution of the calculated qmc into the predictive equations (AFRC, 1993) resulted in a mean maintenance requirement of 57·6 MJ/day (0·464 MJ/kg M0·75/day) whilst the mean value derived from the linear model describing the experimental data was 82·5 MJ/day (0·664 MJ/kg M0·75/day). The mean efficiencies of utilization of ME for milk production derived from AFRC (1993) and the linear regression model were 0·653 MJ/MJ and 0·625 MJ/MJ respectively.

Calorimetric studies on the effect of dietary energy source and environmental temperature on the metabolic efficiency of energy utilization by mature Light Sussex cockerels

1969 ◽  
Vol 72 (3) ◽  
pp. 479-489 ◽  
Author(s):  
D. W. F. Shannon ◽  
W. O. Brown
Keyword(s):  
Heat Production ◽  
Environmental Temperature ◽  
Metabolizable Energy ◽  
Energy Utilization ◽  
Metabolic Efficiency ◽  
Heat Increment ◽  
Energy Retention ◽  
Calorimetric Studies ◽  
The Relationship ◽  
Maize Oil

SUMMARYExperiments to determine the net availabilities of the metabolizable energy (NAME) of a cereal-based diet and a maize-oil diet for maintenance and lipogenesis and the effect of environmental temperature on the NAME of the cereal-based diet are described. Four 1- to 2-year-old Light Sussex cockerels were used.The relationship between ME intake and energy retention was linear for each diet. The NAME'S of the cereal-based diet given at 22° and 28 °C (70.6 ± 1.83 % and 73.6 ± 3.54%, respectively) were significantly (P < 0.05) lower than the NAME of the maize-oil diet (84.1 ± 1.85%). It is concluded that the beneficial effect of maize oil on the efficiency of energy utilization is due to a reduced heat increment rather than a reduction in the basal component of the heat production. The higher efficiency from the maize-oil diet led to an increase in the energy retained as fat.The mean fasting heat production at 28 °C was 15 % lower than at 22 °C (43.2 ± 1.45 and 51.2 ± 1.09 kcal/kg/day, respectively). The NAME of the cereal-based diet was not significantly different when the birds were kept at 22° or 28 °C. The lower metabolic rate at 28 °C was reflected in a lower maintenance requirement and in an increase in the deposition of body fat.

Further studies on the energy and protein metabolism of pigs growing at a high ambient temperature, including measurements with fasting pigs

1974 ◽  
Vol 19 (2) ◽  
pp. 211-220 ◽  
Author(s):  
C. W. Holmes
Keyword(s):  
High Temperature ◽  
Heat Production ◽  
Protein Metabolism ◽  
Live Weight ◽  
High Ambient Temperature ◽  
Metabolizable Energy ◽  
Energy Losses ◽  
Apparent Digestibility ◽  
Energy Retention ◽  
Urinary Nitrogen

SUMMARY1. The experiment was designed to compare the protein and energy metabolism of pigs growing at 25°c or 34°C. The pigs were given two levels of feeding while growing between 25 and 75 kg live weight.2. The high temperature was associated with increases in rectal temperature of 1·2 to 20°C. Both pigs on the higher level of feeding at 34°C became lame in their hind legs.3. The high temperature was also associated with increases in heat production and in urinary nitrogen and energy losses for pigs fed at the higher level of feeding only; however fasting heat production was not affected significantly by temperature. The high temperature had no effect on the apparent digestibility of the diet.4. It was calculated from data for pigs at both levels of feeding kept at 25°C, that efficiency of utilization of metabolizable energy (ME) above maintenance was 71%, and the maintenance requirement for ME was 100 kcal/kg0·75 day. Energy retention was reduced at 34°C in pigs fed on the higher level of feeding.

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