Mcal Digestible Energy Research Articles

Effects of Maternal Low-Energy Diet during Gestation on Intestinal Morphology, Disaccharidase Activity, and Immune Response to Lipopolysaccharide Challenge in Pig Offspring.

Maternal nutrition during gestation is involved in the offspring’s intestinal development and immunity. The aim of this study was to (1) determine the effects of maternal energy on intestinal digestion and absorption function in offspring, using pigs as a model; and (2) to evaluate the potential effect and mechanisms of maternal energy in modulating immune responses of lipopolysaccharide (LPS)-challenged piglets. After mating, thirty-six nine-parity sows (Landrace × Yorkshire), body weight (BW) (initial body weight 233.56 ± 2.77 kg) were allocated to two dietary treatment groups; a control diet (CON) group and a low-energy diet (LED) group. The nutrient levels of the CON were based on the nutrient recommendations by the National Research Council (NRC, 2012), and contained 3.40 MCal digestible energy (DE)/kg diet and 7.3% crude protein; while the LED contained 3.00 MCal DE/kg diet. The dietary treatments were introduced from day 1 of gestation to farrowing. Intestine samples were collected from the pigs’ offspring at birth, and at weaning (day 28 post-birth). At weaning, male pigs from control and LED groups were intraperitoneally injected with LPS (50 μg/kg body weight) or saline (n = 6), and sacrificed at 4 h post-injection to collect blood, intestine and digesta samples for biochemical analysis. The results indicated that the maternal LED markedly decreased the BW, small intestinal weight, and the ratio of jejunum and ileum villus height to crypt depth in the offspring. Moreover, the activities of lactase and sucrase in newborn piglets’ intestine, and sucrase and maltase in weaning piglet intestine were markedly decreased by the maternal LED. In addition, maternal LED significantly increased the mRNA relative expression of ileal IL-6 and TNF-α in newborn piglets. Plasma IL-1β concentration and colonic Escherichia coli amount were affected by maternal diet (p < 0.05) and LPS challenge (p < 0.001). Maternal LED significant increased the mRNA relative expression of ileal TLR-4, IL-1β and NF-κB as well as decreased ZO-1 in weaning pigs after LPS challenge (p < 0.05). In conclusion, decreasing energy intake could suppress the offspring’s intestinal digestion and absorption function, and increase the susceptibility of weaning piglets to LPS challenge.

Effect of an energy supplementation, weaning and oestrous synchronisation on ovarian activity and ovulation in early postpartum primiparous Bos indicus cows raised in the tropics of Costa Rica

To evaluate the effect of an energy supplementation, 26 postpartum Bos indicus cows were assigned either to receive an energy diet supplementation (n = 11, SSD) or no supplementation (n = 15, NSSD). Cows in the SSD treatment received a diet consisting of 5.5% crude protein, 2.85 Mcal digestible energy per head per day, at 1% ratio of the average bodyweight, started 23.5 ± 3.4 days after calving and continued for 44 days. In contrast, NSSD cows were grazing only native pastures during the experiment. All cows were synchronised at 65 days postpartum with a subcutaneous progestin ear implant (Norgestomet) for 9 days and an injection of oestradiol valerate and Norgestomet at the same time as implant placement. A random sample of six animals from each treatment was scanned with ultrasound every 6 h and the dominant follicle (s) was measured until ovulation occurred or after 114 h. The nadir of body condition score for the NSSD was observed at 37.5 ± 3.4 days postpartum, while SSD was at 22.3 ± 7.9 days (P &lt; 0.01); no differences (P &gt; 0.05) in dorsal backfat thickness or average bodyweight between treatments were observed. During the ultrasound-scanning period, four of six cows ovulated in the SSD treatment and five of six in the NSSD. No difference (P &gt; 0.05) was observed at the time of ovulation after progestin implant withdrawal (55.8 ± 7.8 h in NSSD vs 94.5 ± 21.7 h in SSD). The largest follicle diameter at the beginning of the scanning was in SSD treatment (7.25 ± 1.4 mm in SSD vs 5.0 ± 0.8 mm in NSSD), whereas at the time of ovulation, it was similar (15.2 ± 1.8 mm in SSD vs 11.0 ± 1.4 mm in NSSD) between the treatments (P &gt; 0.05). The resumption of ovarian activity was similar between SSD (69 ± 20.7 days, ranging from 42 to 83 days) and NSSD (69.8 ± 6.4 days, ranging from 59 to 73 days). The length of postpartum anoestrus was influenced by the onset of the nadir of body condition score. Energy diet supplementation did not influence the onset of ovarian activity.

Potential Protein Deposition in the European Wild Boar (Sus scrofa L.)

L.) is perceived to be very slow. However, there is no available information on the genetic potential of these animals in terms of potential lean tissue growth.The aim of the study was to determine the maximum capacity for protein deposition (operational PDmax) in wild boars under controlled environmental conditions. Four diets were formulated containing different levels of digestible energy (DE): 2.2, 2.4, 2.6, and 2.8 Mcal DE kg

Insulin Sensitivity in Thoroughbred Geldings: Effect of Weight Gain, Diet, and Exercise on Insulin Sensitivity in Thoroughbred Geldings

The effects of dietary energy source, controlled weight gain, and exercise restriction on insulin sensitivity (SI) were studied in mature Thoroughbred geldings with body condition scores (BCS) of 4.3 ± 0.1. Two dietary energy sources were used, one high in starch and sugar (HS; n = 9) and one high in fat and fiber (HF; n = 7), and horses were fed 20 Mcal digestible energy (DE)/day above maintenance requirements to encourage weight gain. Using the minimal model of glucose and insulin dynamics, no differences in SI between groups were noted before initiation of treatment concentrate feeding. After dietary acclimation, SI was decreased in HS ( P < 0.01) as compared with HF. After 32 weeks of controlled weight gain (90.8 kg; final BCS, 7.0 ± 0.1), SI remained lower in HS ( P = 0.07) but did not change from the preweight gain value. SI in HF did not change between the start and end of weight gain. After completion of weight gain, exercise was restricted for 2 weeks, resulting in a reduction in SI in HF ( P = 0.03) but no change in HS. It was concluded that dietary energy source may be more influential than weight gain on SI in the mature Thoroughbred gelding between BCS 4 and 7. The higher SI found in horses consuming the HF diet appeared to be partially dependent on some level of physical activity.

Glycemic Index of Ten Common Horse Feeds

Abstract Two 6 × 6 Latin-square designed experiments examined the glycemic responses to 10 common equine feeds in six Quarter Horse mares. At 8:00 am of the sampling days, horses were offered a meal of 1 of 10 common feeds. The amount of feed offered was calculated on an isocaloric basis at 4 Mcal digestible energy per meal. Jugular blood samples were collected for 300 minutes after feeding, and plasma was analyzed for glucose concentration. The results showed that plasma glucose values peaked approximately 90 to 120 minutes after eating, whereas glycemic index (GI) values ranged from 7 to 129 based on a standard of oats set at a GI of 100. The four feeds with the highest GI values (sweet feed, corn, jockey oats, and oats) were greater (P

Nutritional value of wheat and corn distiller’s dried grain with solubles: Digestibility and digestible contents of energy, amino acids and phosphorus, nutrient excretion and growth performance of grower-finisher pigs

Two experiments were conducted to evaluate the nutritional value of distiller’s dried grains with solubles (DDGS) samples derived from corn, wheat and a wheat/corn blend (4:1). Specifically, the digestibility and digestible contents of energy, amino acids (AA) and P, N and P excretion, and growth performance were determined in grower-finisher pigs. In exp. 1, 12 ileal cannulated barrows (64.6 ± 6.4 kg) had restricted access (2.6 × maintenance) to a wheat-control diet or one of three diets containing 40% DDGS sample of corn, wheat or wheat/corn origin that replaced wheat. For energy, apparent total tract digestibility was highest for wheat (85%; P &lt; 0.05) and did not differ among the DDGS samples (77 to 79%; P &gt; 0.10). Total tract digestible energy (DE) was higher for corn DDGS (4292 kcal kg-1 DM; P &lt; 0.05) than wheat/corn DDGS, wheat DDGS and wheat samples (4038, 4019 and 3807). For lysine, apparent ileal digestibility (AID) was highest for wheat (71%; P &lt; 0.05) and did not differ among DDGS samples (59 to 63%; P &gt; 0.10). The AID lysine content was highest for corn DDGS (0.51% DM; P &lt; 0.05), intermediate for wheat/corn DDGS and wheat DDGS (0.45 and 0.42), and lowest for wheat (0.37%). For P, total tract digestibility was lowest for wheat (15%; P &lt; 0.05) and did not differ among DDGS samples (53 to 56%; P &gt; 0.10). Total N excretion was highest for wheat/corn DDGS and wheat DDGS (55 and 58 g d-1; P &lt; 0.05), intermediate for corn DDGS (44) and lowest for wheat (36). Total P excretion did not differ among DDGS (11 g d-1) and was lowest for wheat (8; P &lt; 0.05). In exp. 2, 100 pigs (52.0 ± 3.3 kg) were fed a wheat-pea control diet or one of three diets containing 25% of the three DDGS samples (3.375 Mcal DE kg-1; 2.50 g SID lysine Mcal-1 DE) for 5 wk. Overall, average daily feed intake (ADFI) and daily gain (ADG) were higher for pigs fed the wheat control diet than the DDGS-containing diets (P &lt; 0.05), but feed efficiency did not differ (P &gt; 0.10). In summary, the digestible nutrient content of wheat DDGS is lower than corn DDGS and higher than wheat. Followin g pre-characterization of digestible nutrient profile, feeding DDGS reduced growth performance indicating that further research is required to improve the nutritional value of DDGS. Key words: Distiller's dried grains with solubles, pig, digestibility, energy, amino acid

Xylanase supplementation improves energy digestibility of wheat by-products in grower pigs

Value-added processing of cereals produces high-value fractions for food and bio-processing application and by-products that are used in animal nutrition to reduce feed costs. Wheat by-products contain arabinoxylans that might limit nutrient digestibility. Effects of xylanase supplementation (0 or 4375 U/kg feed) on energy digestibility were studied in a wheat control and by-product diets (30% millrun, middlings, shorts, screenings, and bran) in a 2 × 6 factorial arrangement. The wheat control diet was formulated to contain 3.34 Mcal digestible energy (DE)/kg and 2.8 g apparent digestible lysine/Mcal DE, and included 0.4% chromic oxide as a marker for digestibility. Twelve ileal-cannulated pigs (32.5 ± 2.5 kg) were each fed seven of 12 diets. Faeces and then digesta were each collected for 2 d, and diet digestibility values are reported. Wheat had higher ileal and total-tract energy digestibility than by-products (P < 0.01). Xylanase improved energy digestibilities for by-products (P < 0.001) but not for wheat. Among by-products, ileal energy digestibility was lowest for middlings (62%), then bran < screenings < millrun, and highest for shorts (66%). Xylanase improved (P < 0.05) ileal energy digestibility of millrun by 19% to 76%. Total-tract energy digestibility of millrun improved from 72 to 79% (similar to wheat) with xylanase (P < 0.05). In summary, xylanase improved energy digestibility in the selected wheat by-product diets, indicating that arabinoxylans in wheat by-products limit nutrient digestibility.

Effect of carbohydrase supplementation of wheat- and canola-meal-based diets on growth performance and nutrient digestibility in group-housed weaned pigs

Fibrous components in canola meal and wheat limit their effective use in diets for weaned pigs. Effects of supplementing a carbohydrase (845 and 327 Units g-1 xylanase and β-glucanase) to a wheat-canola meal diet on growth performance, small intestine nutrient digestibility and digesta viscosity were investigated. Ninety-six weaned pigs (7.2 ± 1.2 kg) had free access to control diet [65% wheat, 25% canola meal; 3.15 Mcal digestible energy (DE) kg-1, 10.6 g digestible lysine kg-1] or control diet supplemented with carbohydrase at three inclusion rates (1, 2, or 4 g kg-1) for 28 d. Four pigs were housed per pen for six pens per diet. On days 19 to 21, six pigs per diet were euthanised to collect small intestine digesta. Carbohydrase increased average daily feed intake (ADFI) and average daily gain (ADG) quadratically (P &lt; 0.01) for days 1 to 28, resulting in 16% higher ADFI and 13% higher ADG for 2 g kg-1 carbohydrase compared to control. Carbohydrase did not affect feed efficiency (P &gt; 0.10). The ADG was positively correlated to ADFI (r = 0.94; P &lt; 0.01), but not to feed efficiency (P &gt; 0.10). Carbohydrase did not affect digestibility of dry matter (DM) and energy (P &gt; 0.10). Carbohydrase at 4 g kg-1 only reduced digesta viscosity 30% in the distal small intestine compared to control (P &lt; 0.05). Carbohydrase supplementation increased ADFI and thereby ADG, but not feed efficiency and nutrient digestibility, suggesting that reduction of dietary fibrous components using carbohydrase may stimulate voluntary feed intake of pigs fed diets limiting in DE. Key words: Carbohydrase, canola meal, wheat, pig, feed intake, digestibility

Effect of dietary particle size and carbohydrase and/or phytase supplementation on nitrogen and phosphorus excretion of grower pigs

The effect of dietary particle size and enzyme supplementation on N and P excretion were investigated in a 3 × 2 × 2 factorial arrangement, with three particle sizes (400, 700, or 850 μm), two levels of a carbohydrase cocktail [0 or 444 added units (U) β-glucanase plus 1385 added U xylanase kg-1 diet], and two levels of phytase (0 or 374 added U phytase kg-1 diet), for a total of 12 dietary treatments. Diets (70% barley, 25% peas) were formulated to contain 3.25 Mcal digestible energy (DE) kg-1, 1.6 g digestible lysine Mcal-1 DE, and 1.2 g kg-1 available P. Sixty pigs (25.3 ± 1.4 kg) had restricted access (3 × maintenance DE) to feed, and five individual pig observations for each of the 12 mash diets were obtained. Reducing particle size from 700 to 400 µm reduced total P excretion 12% and increased P digestibility and retention 15% (P &lt; 0.05), while phytase reduced total P excretion 28% and increased P digestibility and retention 42% (P &lt; 0.01). Reducing particle size from 850 and 700 to 400 µ m decreased total N excretion 4 and 7%, respectively (P &lt; 0.05). Carbohydrase did not affect P digestibility or excretion (P &gt; 0.10), but increased digestibility of N and energy (P &lt; 0.05). Carbohydrase interacted with particle size for energy digestibility (P &lt; 0.01) and with phytase for N and energy digestibility (P &lt; 0.05). Particle size affected N excretion and energy digestibility more than enzyme supplementation, while phytase affected P excretion more than particle size, suggesting that particle size reduction and phytase supplementation are effective to reduce nutrient excretion of grower pigs. Key words: Particle size, carbohydrase, phytase, pig, nitrogen, phosphorus

Effect of dietary particle size and nutrient supply on energy digestibility and nitrogen excretion in ileal cannulated grower pigs

Diets with two particle sizes (600 and 900 µm) and two nutrient supply levels [digestible energy (DE)-limiting and amino acid (AA)-limiting; 2.8 and 1.8 g digestible lysine Mcal-1 DE, 3.15 and 3.40 Mcal DE kg-1, respectively] were used. Eight ileal cannulated pigs (25 ± 2 kg) had restricted access to feed (3 × maintenance DE) for three periods (N = 6 per diet). Reducing particle size from 900 to 600 µm did not alter urinary or total N excretion (P &gt; 0.10), reduced faecal N excretion 11%, increased total-tract digestibility of N and energy 3%, and increased ileal digestibility of N 9% and energy 11% (P &lt; 0.05). Reducing particle size increased energy digestibility but did not reduce total N excretion. Key words: Particle size, pig, nitrogen, excretion, energy, digestibility

Effects of dietary protein and fermentable fiber on nitrogen excretion patterns and plasma urea in grower pigs.

Effects of dietary protein concentration (high, 18.5; low, 15.7%) and fermentable fiber (control; soyhulls, SH; and sugar beet pulp, SBP) on N excretion patterns and plasma urea were tested in a 2 x 3 factorial arrangement. The objectives were: 1) to determine if reduced dietary protein together with fermentable fiber would reduce urinary N excretion further than a single diet manipulation, 2) to determine if effects of diet manipulations were similar between pigs with restricted and free access of feed, and 3) to further develop predictions of urinary N excretion using plasma urea. Diets were formulated to 3.30 Mcal digestible energy (DE)/kg and 2.4 g of digestible lysine per Mcal DE, and supplemented with lysine, methionine, tryptophan, threonine, isoleucine, leucine, or valine to ensure meeting an ideal AA profile. Pigs (30.5 +/- 3 kg; n = 36) were housed in metabolism crates with restricted access to feed (3 x 110 kcal DE/kg BW(0.75)) from d 1 to 18, and free access from d 19 to 26. Feces and urine were collected from d 15 to 18 and d 23 to 26, and blood was sampled on d 17 and 25. With restricted access to feed, urinary N was reduced 28% and N retention was reduced 12% for the low- compared to high-protein diet (P < 0.01; as g/d). Fecal N was increased 4% units for SH and 6.5% units for SBP (P < 0.01; as % of N intake) and urinary N was reduced 5% units for SH (P < 0.10) and 9% units for SBP (P < 0.05) compared to the control. With free access to feed, urinary N was reduced 27% (P < 0.05; as g/d) and N retention was reduced 7% (P < 0.10) for the low- compared to high-protein diet. Fecal N was increased 5% units for SH and 9% units for SBP (P < 0.001; as % of N intake), and urinary N was reduced 9% units for SH and 10% units for SBP (P < 0.01) compared to the control. For either restricted or free access to feed, fermentable fiber did not affect N retention (P > 0.10). A protein x fiber interaction was not observed for urinary N excretion (P > 0.10), indicating that reducing dietary protein and including fermentable fiber reduced urinary N excretion in an additive manner. Daily urinary N excretion was related positively and linearly with plasma urea in pigs with free access to feed (R2 = 0.71; at 0800). In summary, reduction of dietary protein reduced urine N excretion, and fermentable fiber shifted N excretion from urine to feces. Effects of dietary protein and fermentable fiber on reducing urinary N excretion are additive.

Lambs fed protein or energy imbalanced diets forage in locations and on foods that rectify imbalances

Ruminants eat a variety of foods from different locations in the environment. While water, cover, social interactions, and predators are all likely to influence choice of foraging location, differences in macronutrient content among forages may also cause ruminants to forage in different locations even during a meal. We hypothesized that lambs forage at locations containing foods that complement their basal diet and meet their nutritional needs. Based on this hypothesis, we predicted that lambs ( n=12) fed a basal diet low in protein and high in energy would forage where a high-protein food (Food P) was located, and that lambs ( n=12) fed a basal diet low in energy and high in protein would forage where a high-energy food (Food E) was located. Food P was a ground mixture of blood meal (50%), grape pomace (30%), and alfalfa (20%) that contained 47% crude protein (CP) and 2.211 Mcal/kg digestible energy (DE). Food E was a ground mixture of cornstarch (50%), grape pomace (30%), and rolled barley (20%) that contained 6% CP and 3.07 Mcal/kg DE. Food P provided 212 g CP/Mcal DE, whereas Food E provided 20 g CP/Mcal DE. Lambs growing at a moderate rate require 179 g CP and 3.95 Mcal DE. During Trial 1, we determined if lambs foraged to correct a nutrient imbalance, and if they preferred a variety of foods (Foods P and E) to only one food at a location (Food P or E). During Trial 2, we determined if nutrient-imbalanced lambs foraged in the location with the food that corrected the imbalance when the location of the foods changed daily. During Trial 3, lambs were offered familiar foods (Foods P and E) at the location furthest — and novel foods (wheat and soybean meal) at the location nearest — the shelter of their pen. During all three trials, lambs foraged most at the location with the food that contained the highest concentration of the macronutrient lacking in their basal diet, but they always ate some of both foods. Lambs did not feed exclusively at the location with a variety of foods (P and E). Rather, they fed at the location nearest the shelter that contained the macronutrient lacking in their diet. As availability of the food with the needed macronutrient declined in one location, lambs moved to the nearest location that had food with the needed macronutrient. When food that complemented their basal diet was moved to a different location, lambs foraged in the new location. Collectively, these results show that lambs challenged by imbalances in energy or protein selected foods and foraging locations that complemented the nutrient content of their macronutrient imbalanced basal diets.

Protein and energy value of pearl millet grain for mature goats.

We conducted two studies to assess the protein and energy value of pearl millet grain (Pennisetum glaucum [L.] R. Br.) for mature goats. In Exp. 1, 15 2-yr-old male castrated goats were gradually introduced over a 4-mo period to three all-grain diets consisting of 100% corn (Zea mays L.), 50:50 corn:pearl millet, and 100% pearl millet. After the adjustment to all-grain feeds, the goats were fed the diets in metabolism crates for 2-d adjustment and 7-d total collection periods. For Exp. 2, complete diets containing the three grain treatments (corn, 50:50 corn:pearl millet, and pearl millet) as 40% of the total DM as fed (the remainder was mainly alfalfa meal and mineral supplement) were balanced to contain 16% crude protein (CP) and 2.24 Mcal digestible energy (DE)/kg on an air-dry basis. Twelve mature (4- to 6-yr-old) buck goats were randomly assigned to diets and fed in pens for 14 d and then moved to metabolism crates for 10-d adjustment and 10-d total collection periods. In Exp. 1, DM intake was unaffected by dietary treatment, but digestibility of DM and organic matter was lowest (P < .10) in goats fed 100% pearl millet. Digestibility of complete diets also decreased (P < .10) as corn was replaced by 50 or 100% pearl millet, but DM intake increased (P < .10) on the 100% millet diet. In both experiments, substituting pearl millet for corn had no effect on nitrogen retained by the goats. Metabolizable energy of pearl millet was only 92% that of corn, but ME intake was similar when the grains were fed as 40% of the dietary DM. Pearl millet has potential as a major energy feed for goats in areas where it can be economically produced.

Mechanical properties of metacarpal bones of foals fed different energy and phosphorous levels

SummaryThe mechanical and geometric properties of metacarpal bones of 41 Quarter Horse yearlings fed diets with different energy and phosphorus levels were tested and compared. A 2 times 3 factorial experiment was used to compare 2 energy sources and 3 levels of dietary phosphorus. The 2 energy sources were based either on alfalfa (2.65 Mcal digestible energy [DE]/kg dry matter [DM] feed) or on grain (3.09 Mcal DE/kg DM). In each diet type, the 3 phosphorus concentrations included: an unsupplemented, low phosphorus (LP) diet; a normal phosphorus (NP) diet supplemented to meet NRC (1978) requirements for weanling foals; and a high phosphorus (HP) diet supplemented to supply 150% of 1978 NRC phosphorus requirements. At the completion of the feeding trial, the yearling horses were destroyed and the metacarpal bones recovered. The left metacarpus was serially sectioned at 0.5 cm thicknesses with a band saw and a section was sampled for histology and measurement of geometric properties including the rectangular moments of inertia (Ix, Iy), the products of inertia and principal moments of inertia (Ixx, Iyy). The moments of inertia were then recalculated to the change in orientation of the x‐y axes and symbolised Ix1 and Iy1. Energy intakes were similar despite differences in energy content of the forage and grain diets. However, forage‐fed yearlings had lower (p&lt;0.0589) breaking strengths (23.4 kilograms per square inch [ksi] than grain‐fed horses (25.4 ksi). The geometric properties between LP and NP groups did not differ. However, the geometric properties (Ix1, Ixx, Iyy) differed (p&lt;0.05) between the HP groups and the LP and NP groups. Within the NP group, (Iyy) differed (p&lt;0.038) between males and females. The right metacarpus, with both small metacarpal bones removed but with the periosteum intact, was loaded in a 4‐point bending until failure. The metacarpal bones were placed in a specially‐made Instron tester made so that the mid‐diaphyses were loaded. All bones failed in a single plane at right angles to the main axis of the bone. Seventeen of the 41 bones (41.5%) fractured through the nutrient foramen. The mechanical properties of males and females did not differ except in the NP group wherein stiffness of the metacarpal bone of females was lower (p&lt;0.05). In the NP group, males were 14% heavier (p&lt;0.0384) than females. Although most mechanical properties did not differ between the LP and NP groups, the HP group had a higher load at yield point (6397 N) than the LP group (5789 N). Phosphorus intakes, therefore, affect both mechanical strength and geometric properties of growing horses.

Genotype and sex effects on the relationship between energy intake and protein deposition in growing pigs.

Seventy-two crossbred (Large White X Landrace) pigs were used in a 3 X 7 factorial experiment to investigate the response of two strains of boars (strains A and B) and of castrated male pigs (strain B) to seven levels of intake of a single diet (ranging from 5.3 Mcal digestible energy [DE]/d to ad libitum) between 45 and 90 kg live weight. All aspects of growth performance and body composition were affected to different degrees by both strain and sex. At all levels of energy intake strain A boars grew faster, had a lower feed to gain ratio and contained less fat and more water in the empty body than strain B boars, which in turn exhibited faster live weight gain and more efficient and leaner growth than castrated males. The magnitude of the differences in growth performance between strain A and strain B boars and castrates increased with increased energy intake above 7.88 Mcal DE/d, and these differences were associated with concomitant strain differences in their respective capacity for protein growth and in the relationship between energy intake and protein deposition. For strain A boars the rate of protein deposition increased linearly from 92 to 188 g/d with increased energy intake from 5.3 Mcal DE/d to ad libitum. For strain B boars and castrates the rate of protein deposition increased linearly with increased energy intake up to 7.88 Mcal DE/d, but thereafter it remained constant at 128 and 85 g/d, respectively. For castrates protein deposition was depressed (P less than .01) when the diet was offered ad libitum. Strain A boars had a higher energy requirement for maintenance (3.55 Mcal DE/d) than strain B boars (2.77 Mcal DE/d) or castrates (2.60 Mcal DE/d). Strain A boars also contained less protein and more water in the fat free empty body than the other two pig types.

Effect of protein and lysine levels in the diet on body gain composition and energy utilization in growing pigs.

Eight replicates of four Large White littermate female pigs were used to evaluate the effect of protein and lysine levels in the diet on the efficiency of protein and energy utilization. In each replicate, one pig was slaughtered at about 20 kg live weight and the others received three diets that contained (per Mcal digestible energy) 37.5 and 2.00 g (diet pl), 37.5 and 2.35 g (diet pL) or 45.0 and 2.35 g (diet PL) of digestible protein and lysine, respectively. Pigs were slaughtered after a 7-wk period. Tissue and chemical composition of the gain and energy and nitrogen gain were determined by using the comparative slaughter technique. Metabolizable energy (ME) intakes were similar in the treatments. Pigs fed the pl diet had a smaller body weight and muscle gain and retained less nitrogen and more lipids than pigs fed pL and PL diets. The decrease in the level of nonessential nitrogen in the diet (pL vs PL) did not affect body weight and muscle gain and the amount of nitrogen retained in muscle tissues. However, pigs given the PL diet had a higher total nitrogen retention and a lower fat deposition and exhibited a higher heat production. For each gram of additional protein catabolized for energy purposes (PL vs pL), heat production was increased by 1.8 kcal. The amount of lysine per unit of muscle gain (38 g/kg) or protein deposited (120 g/kg) was independent of protein and lysine levels in the diet. Estimates of energy (indirect calorimetry) and nitrogen (balance technique) retention were also obtained on the same animals; results were comparable with data obtained by direct measurements.

Effect of dietary energy level on the performance of individually housed early-weaned piglets in relation to environmental temperature

An experiment involving 72 individually housed piglets was conducted to determine the interactive effects of environmental temperature and dietary energy level on the performance of early-weaned piglets maintained for six weeks in environmental temperature of 28, 22 or 16°C. Two diets were formulated to supply 3.1 (low energy diet) and 3.6 (high energy diet) Mcal digestible energy per kg of feed. The high-energy diet had greater ( P < 0.01) energy and nitrogen digestibility than the low-energy diet. Digestibilities were similar in piglets exposed to 22 and 28°C and higher ( P < 0.05) than in those housed at 16°C. Exposure to a low temperature (16°C) increased feed intake by 8% ( P < 0.05) and feed to gain ratio by 11% ( P < 0.01), whereas exposure to a warm environment (28°C) decreased feed intake by 25% ( P < 0.01) and growth rate by 28% ( P < 0.01) compared with piglets housed at thermal neutrality (22°C). The effect of dietary energy level on the rate of weight gain, DE intake and DE to gain ratio was dependent upon environmental temperature in which piglets were maintained. Compared with the high-energy diet, the low-energy diet depressed DE intake by 9.2% ( P < 0.05) and rate of weight gain by 14.1% ( P < 0.01) and increased DE to gain ratio by 5.5% ( P < 0.05) in piglets housed in the warm environment. Under cold conditions both low and high energy diets resulted in similar DE intake, rate of weight gain and DE to gain ratio.

NUTRIENT UTILIZATION OF PELLETED AND UNPELLETED FORAGES BY PONIES

Two separate digestion studies using mature ponies evaluated nutrient utilization of unpelleted alfalfa, brome, slough and oat hays and pelleted alfalfa, oat and barley hays grown in Saskatchewan. Alfalfa and cereal hays provided between 2.33 and 2.58 Mcal digestible energy (DE)/kg dry matter (DM). Brome and slough hay supplied 2.13 and 1.75 Mcal DE/kg DM, respectively. Alfalfa hay had a higher digestible crude protein content than other forages tested within each trial. Calcium (Ca) availability was lower from oat hay than other unpelleted forages (P &lt; 0.05). Ponies were in negative Ca balance when either oat or barley hay pellets were fed; this occurred through an apparent increase in urinary Ca excretion. Phosphorus (P) balances were negative when slough hay or cereal hays were fed. Oxalate and phytate determinations were made in forages and concentrations of 0.26–1.3% oxalate and 0.06–0.44% phytate were obtained. Voluntary intakes of alfalfa and brome hay by ponies were higher than oat or slough hays (P &lt; 0.05). Pelleted alfalfa hay was eaten in larger amounts than oat or barley hay pellets (P &lt; 0.05). Of the forages tested, alfalfa hay was considered to be the best hay for supplying nutrients for horses. Cereal hays provide a good source of energy and protein for mature equids but would require macromineral supplementation. Key words: Forages, pony, nutrient utilization

Influence of level of feeding and nutrient content of the concentrate on growth and development of yearling horses.

Three experiments using 63 Thoroughbred and Quarter Horse yearlings were conducted to evaluate the influence of level of feeding, and protein and calculated energy content of pelleted concentrates on growth and bone development. Animals were housed in drylot paddocks and individually fed concentrates twice daily. Coastal bermudagrass (Cynodon dyctylon) hay was group-fed. Yearlings offered a corn-based concentrate (3.56 Mcal digestible energy [DE]/kg) consumed levels of dry matter similar to yearlings fed a mixed-grain concentrate (3.32 Mcal DE/kg but consumed slightly more digestible energy. No differences in growth or bone development were detected. Yearlings fed restricted levels of concentrate that provided approximate National Research Council (NRC) recommendations for protein and DE had lower weight and girth gains (P less than .05) than those provided ad libitum concentrate intake during two 1.5-h daily feeding periods. Restricting concentrate intake had no effect on skeletal growth (P less than .05) but resulted in numerically lower values for bone radiographic density. Protein addition to a diet restricted to approximate NRC energy intake recommendations had no effect on weight gain, body measurements or bone mineral deposition (P greater than .05) and growth and development was less than that resulting from higher intakes of a lower protein concentrate.

Paraformaldehyde Compared with Formic Acid As a Direct-Cut Silage Preservative

In two experiments, direct-cut grasslegume forage ensiled with planned 2.5% of 90% formic acid and forage ensiled with .5% paraformaldehyde in the dry matter were compared. In the second experiment untreated silage was compared also. In 1971 the two silages were fed ad libitum as the sole ration for 50 days to 30 dairy heifers paired on body weight. In 1972 the three silages were fed in the same way for 91 days to 24 dairy heifers blocked on body weight. Daily gains averaged over the 2 yr were nearly identical on formic and paraformaldehyde silages (812 versus 817g) and considerably better than on untreated silage (258g) in the 2nd yr. These gains resulted from comparable intakes (256 versus 263kcal digestible energy/kg.75), partial feed conversions (8.4 versus 9.1 Mcal digestible energy for growth/kg gain) and energy digestibilities (59.2 versus 58.8%) of formic and paraformaldehyde silages. These data on the untreated silage were 230, 18.9, and 58.8. Formic acid and paraformaldehyde were equivalent in producing gain per metric ton of stored forage (111 versus 114kg), which was considerably greater than that of untreated silage (41kg).