The effect of feed processing of novel unheated, low trypsin inhibitor soybeans on the performance of young female turkeys reared from hatch to 21 days of age.

The objective of this study was to evaluate the effects of dietary inclusion of a novel low trypsin inhibitor soybean (LTI) fed as mash or crumbled pellet form on the productive performance and digestibility in turkey poults from hatch to 21 d. A total of 336 Hybrid Converter turkey poults were allocated in groups of 7 to 6 treatments, each with 8 replicate cages. Treatments were arranged as a 3 × 2 factorial with inclusion level of the low trypsin-inhibitor soybean (0, 20, and 40% LTI) and feed form (mash and crumbled pellet). A single batch of feed was mixed for each inclusion level and divided into 2 aliquots: one remaining as mash and the other conditioned at 82°C for approximately 30 s, pelleted and then crumbled. On d 7, 14, and 21 posthatching, BW, and feed intake (FI) were recorded and BW gain (BWG) and feed conversion ratio (FCR) calculated. Excreta samples were collected from d 19 to 21 and pooled by cage. At d 21, intestines were excised, pancreas weights recorded (PRW), and ileal contents collected. There were no interactions (linear, P > 0.05) between LTI inclusion and feed form on BW, BWG, FI, or FCR at d 7 or 21. Increasing LTI resulted in a linear reduction in BW at 7, 14, and 21 d (P < 0.006). Poults fed crumbles were significantly heavier at d 21 than those fed mash feed (P < 0.027) with no interaction of LTI level with feed form. FCR was not significantly greater with increasing LTI. However, poults fed crumbles had a better, lower FCR that those fed mash feed from d 0 to 21 (P < 0.018). There was a significant interaction between feed form and LTI level at 14 d (P < 0.031), but not 7 or 21 d. Pancreatic hypertrophy (PRW) increased linearly with increasing LTI (P < 0.001) with a significant linear interaction with feed form (P < 0.001). Poults fed crumbles had less pancreatic hypertrophy. At 21 d of age, dietary fat digestibility (ALD, %) was linearly reduced with increasing LTI (P < 0.001). However, poults fed crumbles had significantly better fat absorption than poults fed mash (91.2 vs. 85.8%) (P < 0.001), and there was a significant linear interaction between feed form and LTI level (P < 0.001). AMEn was significantly better for the poults fed crumbles compared to mash (3228 vs. 3132 kcal/kg) (P < 0.001), and there was a significant linear interaction between feed form and LTI level (P < 0.001). Based on the results this trial, it is possible to include up to 20% unheated full fat LTI soybeans into poult starter diets after pelleting. Pelleting improves nutrient utilization, allowing for greater incorporation of the LTI soybean in the crumbled diet compared to the mash diet.

Response of turkey poults to soybean lectin levels typically encountered in commercial diets. 2. Effect on intestinal development and lymphoid organs.

Lectins are capable of altering intestinal morphology by binding to and disrupting the intestinal brush border membrane. They are also known to alter the weight of lymphoid organs. Therefore, we evaluated the effect of soybean lectin (SBL) on intestinal morphology and lymphoid organ weights of poults fed diets containing SBL. Dietary treatments evaluated in this study included a cornstarch and casein-based control (lectin-free) semipurified diet (PD) and semipurified diets containing 0.024 or 0.048% SBL (PDL and PDH, respectively). Experimental diets were fed from hatch to 14 d. Morphological evaluation of the intestine involved measurement of the villi height and perimeter, crypt depth, villus:crypt, and thickness of the muscle layer in the jejunum. Intestinal physical characteristics were also determined by measuring intestinal weight, length, and volume. Results indicated that 0.048% SBL in PDH increased villus:crypt and reduced total intestinal length in turkey poults. In addition, both the 0.024 and 0.048% dietary SBL levels reduced thymus weights. It was concluded that dietary SBL up to 0.048% enhanced intestinal development by increasing villus:crypt, but might alter the structural integrity of lymphoid organs.

Versazyme supplementation of broiler diets improves market growth performance.

Day-old male broiler chicks were randomly assigned to 32 floor pens in a completely randomized block design and grown to 6 wk of age. Birds in experiment 1 were fed 1 of 2 basal diets supplemented with or without a protease containing feed additive, Versazyme (VZ). The 4 treatments were 1) control (C), a corn-soybean meal diet that contained 95% of amino acids recommended by NRC except for threonine and isoleucine; 2) C + 0.1% VZ (wt/wt) (C+) in the starter diet only; 3) high (HP) amino acid diet, a corn-soybean meal diet with 100 to 105% of amino acid recommended by NRC except for threonine and isoleucine; and 4) HP + 0.1% VZ (wt/wt) (HP+) in starter diet only. Supplementing both diets with VZ improved BW and feed conversion ratio (FCR) at 21 d of age and BW at 42 d of age. Cumulative 42-d FCR was only improved in birds fed the HP+ diet. Birds in experiment 2 received the following treatments: 1) HP, 2) HP + 0.1% VZ batch A (wt/wt) (A) in starter diet only, and 3) HP + 0.1% VZ batch B (wt/wt) (B) in starter diet only. Enzyme supplementation improved 22-d BW and FCR. There was no significant difference in BW at 43 d of age. Both A and B improved overall FCR (1.758 and 1.751 vs. 1.79 for A and B vs. HP, respectively). In conclusion, supplementation of starter broiler diets with VZ resulted in improved market growth performance.

Influence of diet on a retrovirus-induced obesity and stunting syndrome.

An avian retrovirus, RAV-7, causes a syndrome characterized by stunting, high mortality, and obesity. In this study, the influence of the lipid content of the diet on the RAV-7-induced syndrome was examined. Failure to gain weight, a measure of the stunting, was not influenced by fat content of the diet, but a slight increase in mortality was noted with a low-fat diet.

Dietary electrolyte balance effects on performance and metabolic characteristics in finishing steers.

One hundred twenty Angus and Angus-hereford crossbred steers (337 +/- 3 kg) were used in a randomized complete block design to evaluate the effects of dietary electrolyte balance (DEB; Na + K - Cl) on performance, acid-base status, and plasma mineral concentrations in cattle consuming a high-concentrate, low-fiber (5% cottonseed hull) diet. The steers were blocked into six groups based on BW and pen location, with five steers per pen. The treatments consisted of 0, 15, 30, and 45 mEq of DEB/100 g of DM. Average daily DMI increased linearly (P < .01) with increasing DEB for the first 28 d then increased quadratically (P < .05) for the remainder of the study. Daily gain tended (P < .10) to increase quadratically, whereas gain:feed was not affected by DEB. Carcass marbling score increased quadratically (P < .05), but other carcass measurements were not affected by DEB. On d 42, arterial blood pH was increased quadratically (P < .10) and HCO3 responded cubically (P < .10) to DEB, whereas ionized Ca, pCO2, and pO2 were not affected by treatment. On d 84, pCO2 (P < .10) and HCO3 (P < .05) decreased linearly as DEB increased. On d 42, plasma concentrations of Na, K (P < .10), and Mg (P < .05) decreased quadratically with increasing DEB. Plasma CV concentrations decreased linearly (P < .05) with increasing DEB on d 42. On d 84, total plasma Ca increased linearly (P < .10) with increasing DEB.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary electrolyte balance effects on performance and metabolic characteristics in growing steers.

The effects of dietary electrolyte balance (DEB; mEq of Na + K - Cl/100 g of DM) on performance and acid-base status of growing cattle consuming a corn silage-based diet were established using 120 Angus (n = 60) and Angus crossbred (n = 60) steers (247 +/- 2.4 kg). Treatments consisting of 0, 15, 30, or 45 mEq of DEB/100 g of DM were obtained by varying NH4Cl and NaHCO3. Average daily gain showed a linear increase (P < .05) with increased DEB for the first 28 d and a quadratic response (P < .05) for the remainder of the 84-d study. Average daily feed intake was not affected by DEB the first 28 d. However, feed intake over the entire feeding period showed a linear increase with increasing DEB (P < .01). On d 28, plasma Na, K, and Mg were not affected by DEB, whereas Ca followed a quadratic pattern (P < .10). On d 84, plasma Na and Mg decreased linearly with increasing DEB. Plasma Cl concentrations decreased linearly (P < .01) with increased DEB on d 28 and 84. On d 28 arterial blood pH and HCO3 increased linearly (P < .05) with increased DEB, whereas ionized Ca, pCO2, and pO2 were unchanged. On d 84, arterial blood pH (P < .10), HCO3 (P < .05), and ionized Ca (P < .10) increased quadratically, whereas pO2 and pCO2 were not affected by treatment. Ruminal pH increased linearly (P < .05) with increased DEB on d 28 but showed no differences on d 84. These data indicate that DEB affects performance and systemic values in growing feedlot cattle. A DEB in the range of 15 to 30 mEq seemed to provide normal homeostasis of growing steers fed a corn silage-based diet.

Nutritional, physiological, genetic, sex, and age effects on fat-free dry matter composition of the body in avian, fish, and mammalian species: a review.

The purpose of this review is to outline and interpret the effects of nutrition, physiological state, sex, genetics, and age on composition of the fat-free dry matter of birds, mammals, and fishes in order to test the hypothesis that the protein:ash ratio in the body is constant. Calculations from a broad array of published data revealed that nutritional factors, including mineral, protein and amino acid nutriture, frequency and level of feeding, and energy intake and nonnutritional factors, including physiological state, sex, genetic background, and age of animal, may each alter the ratio of protein:ash in the body. All or part of the response may be associated with changes in accretion of body protein and(or) skeletal development and mineralization imposed by these nutritional and nonnutritional factors. In most cases of amino acid or protein deficiency, the protein:ash ratio was decreased relative to the control because the deposition of protein in muscle and viscera was reduced more than the growth and mineralization of the skeleton. In other cases, the protein:ash ratio was increased relative to a control because the dietary Ca or P intake or absorption limited skeletal mineralization. More knowledge is needed of how skeletal development and protein:ash ratio in the body is regulated, especially under the influence of nutritional, ontogenetic, and physiological variables among different genotypes of mammals, birds, and fishes. Documentation that the protein:ash ratio in the whole body of representative mammals, birds, and fishes is not constant, but is subject to manipulation, has important physiological and economic implications for developing food animals for the efficient production of lean meat.

Response of broilers to DL-methionine hydroxy analog free acid, DL-methionine, and L-methionine.

An experiment was designed to compare graded levels of DL-methionine hydroxy analog, free acid, 88% in aqueous solution; 2-hydroxy-4-(methylthio)butanoic acid (HMB), the aqueous solution of the sodium salt of DL-methionine (40%) (DLM), and crystalline L-methionine (LM) as sources of supplemental methionine activity. The experiment utilized 2160 broilers of each sex grown in separate pens to 7 weeks of age with a lysine-supplemented corn-soybean meal basal diet. These supplements produced a maximum 15% growth response over the unsupplemented basal diet. There were no statistically significant differences among the three sources in producing weight gain and feed conversion. There were no source X level interactions with regard to body weight gain. There was one source X level interaction (at 7 weeks) for feed conversion. The results support the conclusion that when synthetic sources of methionine activity are used to meet the requirement for total sulfur amino acids in practical corn-soybean meal diets for producing 7-week-old broilers, the chicks are capable of utilizing HMB, DLM, and LM with an efficiency that is indistinguishable.

The interaction of phosphorus nutrition and fasting on the survival time of young chickens acutely exposed to high temperature.

Phosphorus nutrition and fasting are dependent factors which markedly influence the tolerance of young chickens to high temperature. A study was conducted to further characterize the nature of this interaction. Male chicks fed low phosphorus diets and fasted 24 hr exhibited significantly shorter survival time after exposure to acute heat when compared to fasted chicks previously fed adequate dietary phosphorus. When chicks were fasted for 48 hr, the effect of previous diet was considerably more pronounced. These results showed that the effect of low phosphorus nutrition was potentiated by fasting 48 hr which in itself improved survival time over that of chicks fasted 24 hr. The apparent metabolic responses of chicks to heat as indicated by changes in plasma glucose and total ketones were not related to the observed dietary effects. Plasma phosphate (Pi) and calcium (Ca) decreased significantly during heat exposure. The Ca/pi molar ratio was increased significantly at heat induced exhaustion, indicating a relatively greater heat induced change in Pi. From the initiation of heat exposure to heat exhaustion, the percent change in Pi, but not Ca, was similar in all groups despite marked differences in the time within which this occurred. We concluded that the effect of low phosphorus nutrition on heat tolerance of young chickens persists after a 48-hr fast. In addition, the effects of previous diet were somewhat more pronounced in 48-hr fasted chicks when compared to those fasted 24 hr.

Postfasting dietary protein requirements of induced molted hens.

An experiment was conducted to determine the dietary protein requirement of induced molted hens during the postfast recovery period. In a temperature-controlled room, Single Comb White Leghorn hens (97 wk of age) were induced to molt for a second time by feed deprivation. After losing 30% of their body weight, they received a corn-soy diet containing 17.0, 14.8, 13.5, or 12.4% protein until the first egg was produced. In each diet, total sulfur amino acids were supplemented to provide a level equal to 5.0% of the protein. Average daily protein intakes were 17.2, 15.7, 13.4, and 11.9 g/day, respectively, for hens fed diets containing 17.0, 14.8, 13.0, and 12.4% protein. Times required from the end of the fast until the first egg produced were 28.0, 28.2, 28.5, and 31.0 days, respectively. Dietary protein level did not significantly influence the time required to begin egg production, body weight at Egg 1, or the hen-day production rate. Three hens from each treatment were sacrificed at Egg 1. No differences were seen in the weight of the left breast muscle, liver, abdominal fat pad, ovary plus ova and oviduct, or in the percent of carcass moisture, fat, or protein. Under the controlled environmental conditions of this experiment, the 12.4% protein diet with supplemental methionine met the postfasting dietary protein requirement.

Effect of overcooked soybean meal on chicken performance and amino acid availability.

Studies were conducted to evaluate the effect of overcooked soybean meals (SBM) on chick growth and amino acid availability. The SBM were custom-prepared at a commercial processing plant by changing the conditions of a desolventizer-toaster (DT) unit. Six progressively overcooked meals (designated SBM1 to 6 with SBM1 as normal, and SBM6 overcooked) were produced by increasing temperature by up to 50% and extending retention time by up to 75% above normal. The meals measured .05, .03, .01, .09, .00, and .00 delta pH of urease activity; 6.10, 5.01, 4.62, 4.83, 2.32, and 1.78 mg/g SBM of trypsin inhibitor activity; 92, 89, 91, 88, 81, and 81% of protein solubility in .2% KOH; and 46, 43, 41, 40, 23, and 19% of protein solubility in .1 M borate at 40 C, respectively. Glucose content in the hydrolysate of the soluble carbohydrate extract did not differ among the meals, indicating no differences in the degradation of sucrose, raffinose, and stachyose with increasing heat treatment. In a chick growth experiment with a methionine-adequate, low-protein diet, chicks fed SBM1 showed significantly greater weight gain than chicks fed SBM3, 5, or 6. The SBM1, 2, 5, and 6 were chosen for a study of amino acid availability. No differences were observed in amino acid content. There were significant differences in apparent amino acid availability to growing chicks, but not in true amino acid availability by adult roosters among the four meals. The results suggest that the temperature or the retention time of a DT unit may be increased by 50% over the usual operating conditions without reducing amino acid availability from SBM.

Effect of a high fat diet fed prior to or at sexual maturity on egg weight.

This study compared the effects of a low fat, high carbohydrate diet with a high fat diet fed prior to or at the onset of egg production on initial egg weight. Commercial egg-type pullets were assigned to one of three dietary regimens: 1) the control (CON), a low fat, high carbohydrate diet, 2) a high fat (HF) diet containing eight parts of fat, and 3) the high carbohydrate diet provided prelay and the high fat diet during the production period (CHO-HF). The carbohydrate prelay and laying diets contained .990 and .943% fat and had a calculated metabolizable energy (ME) value of 2,831 and 2,697 kcal/kg, respectively. The high fat prelay and laying diets contained 8.959 and 8.484% fat with a calculated ME value of 3,202 and 3,032 kcal/kg, respectively. The first 60 eggs produced by each pullet were collected and weighed. At Egg 60, no significant differences were seen in body weight and abdominal adipose tissue. The CON treatment had a significantly greater liver weight, liver lipid content, and ovary weight than the HF or CHO-HF treatments. The CON and HF treatments had a similar hen-day egg production (HDP). The CHO-HF treatment was slow to adjust to the high fat diet and that may have caused the lower HDP that was seen for this treatment. No indication of a failure to adjust to the high fat diet was noted for the HF treatment. Additionally, a high fat diet resulted in higher egg weights.(ABSTRACT TRUNCATED AT 250 WORDS)

Lead-induced egg production decrease in Leghorn and Japanese quail hens.

A study was conducted to compare the response of chicken hens and Japanese quail hens to various levels of dietary lead as plumbus acetate. Egg production was decreased significantly in quail receiving 1 mg lead/kg of diet from day of hatch, and 10 mg lead/kg diet was required to suppress egg production when the metal was given to the quail hens after they had reached sexual maturity. In chicken hens given lead after they had attained approximately 80% hen-day production, a comparable decline in egg production was seen in hens consuming at least 200 mg lead/kg of diet. Total plasma calcium in quail hens was reduced significantly by 10 mg lead/kg of diet, but total plasma calcium in chicken hens was not reduced with levels of less than 200 mg lead/kg of diet. There was no correlation between blood calcium level and decreased egg production in chicken hens consuming dietary lead at levels less than 200 mg/kg diet, suggesting that lead influences egg production in birds through mechanisms that may not be dependent entirely upon calcium metabolism. Removal of lead from the diets of quail was associated with significant increases in egg production and total plasma calcium, but removal of lead from the diets of chicken hens did not cause any increase in total plasma calcium or increase egg production in treated hens. However, hens consuming the highest level of dietary lead (400 mg/kg) did increase significantly their rate of egg production, but this was attributed to recovery from a lead-induced molt.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationships between dietary and plasma concentrations of calcium and phosphorus in intact and ultimobranchialectomized chickens.

Two experiments were conducted with cockerels to determine whether the presence or absence of the ultimobranchial glands would influence the relationship between dietary and plasma calcium and phosphorus. Broiler type cockerels, 16 weeks of age which had been sham operated (SHAM) or ultimobranchialectomized (UBX) 1 to 3 weeks earlier, were fed diets containing 0.8 or 2.4% calcium and 0.13 to 0.33% phosphorus. The SHAM cockerels fed diets containing 0.8% Ca and 0.13% P did not develop hypercalcemia whereas the UBX cockerels fed this diet developed slight significant hypercalcemia after 17 to 21 days. In Experiment I, SHAM cockerels fed the diet containing 2.4% Ca and 0.13% P developed mild, chronic hypercalcemia (12.7 mg./100 ml.) with a plasma phosphorus of 3.03 mg. P/100 ml., whereas the UBX cockerels fed the same diet developed severe hypercalcemia (16.0 mg./100 ml.) and hypophosphatemia, 1.68 mg. P/100 ml. In Experiment 2 the following plasma values were observed after 17 days of consuming the experimental diets: SHAM fed 2.4% Ca and 0.13% P had 10.6 mg. Ca/100 ml. and 3.59 mg. P/100 ml., whereas UBX fed the same diet had 12.8 mg. Ca/100 ml. and 2.24 mg. P/100 ml. The UBX fed 2.4% Ca and 0.33% P for 17 days had plasma values of 10.8 mg. Ca/100 ml. and 4.48 mg. P/100 ml. It is concluded that the presence of the ultimobrancial glands are essential to the regulation of plasma calcium and phosphorus in chickens which consume high calcium-low phosphorus diets.

Tolerance of turkeys to diets high in trypsin inhibitor activity from undertoasted soybean meals.

The objectives were to determine the responses of turkeys to soybean meals (SBM) differing in urease and trypsin inhibitor activity, to estimate the AME of diets containing these SBM, and to determine the responses to supplemental L-Met and L-Lys. Four experiments were conducted with poults 1 to 3 wk of age and one with turkeys 6 to 8 wk of age. In Experiment 1, the trypsin inhibitor activities (TI) were 1.8, 4.2, 5.4, 7.0, and 8.8 mg trypsin inhibited/g SBM (method of Hamerstrand et al., 1981). The corresponding urease indices were .02, .14, .51, .90, and 1.5 pH units. The SBM were 46% of the diet. Significant pancreatic hypertrophy occurred with dietary concentrations of TI of 3.2 mg/g and above. At 4.0 mg TI/g of diet, the feed:gain ratio was increased, but body weight gain and AME of the diet were reduced. In Experiments 2, 3, and 4, poults responded similarly to Met additions to diets containing 46% SBM with TI of 1.8 or 4 mg/g SBM, or to Met or Met plus Lys additions to diets containing 40.7 or 49.6% SBM with TI of 2 or 11 mg/g SBM. In Experiment 5, the SBM contained TI at 4.3, 6.1, 8.9, or 12.5 mg/g. The corresponding urease indices were .05, .27, 1.43, and 1.72 pH units. The SBM were 49.6% of the diet. Using 6 to 8 wk old turkeys, the AME of the four diets were determined to be 2.76, 2.71, 2.58, and 2.57 Mcal/kg. The AME of diets containing 4.4 and 6.2 mg TI/g of diet were reduced (P < .05). In conclusion, through 3 wk of age, turkeys can tolerate soybean TI concentrations of 2.5 mg TI/g of diet. Turkeys 6 to 8 wk of age can tolerate 3 mg of soybean TI/g of diet.

Relationship of dietary calcium level during the prelay phase of an induced molt to postmolt performance.

Leghorn laying hens were induced to molt by a combination of photoperiod reduction and fasting for 14 days, during which time the hens lost 31.5% of their initial body weight. The hens were then assigned to one of four diets containing 1.0, 1.75, 2.5, or 3.5% calcium until egg production resumed. The 3.5% calcium diet was fed to all treatments from the resumption of 5% egg production. Postmolt egg production and feed conversion were not affected significantly. Egg weight, shell weight, and egg specific gravity were not affected consistently. It was concluded that high dietary calcium levels immediately postfast have no adverse effect on postmolt performance.

Effects of lighting program during the growing period and dietary fat during the laying period on broiler breeder performance.

In two experiments, broiler breeders were grown in either of two lighting regimens, fed diets without added fat, and then fed diets with or without 5% added poultry fat during the subsequent laying period. In Experiment 1 half the birds were subjected to decreasing daylength using daylight (800 lx) and half were subjected to 9 h of incandescent light (20 lx) to 20 wk of age. In Experiment 2 the lighting regimen was either an 8-h photoperiod supplied by daylight (800 lx) or an 8-h photoperiod supplied by incandescent light (20 lx) to 20 wk of age. Added dietary fat produced significantly higher egg weight (Experiments 1 and 2), egg production (Experiment 2), and significantly lower fertility and hatchability of fertile eggs (Experiments 1 and 2). Short photoperiods (8 or 9 h) provided by incandescent light produced significantly higher fertility (Experiments 1 and 2) and hatchability of fertile eggs (Experiment 2), and significantly lower egg specific gravity, shell percentage (Experiment 1), egg weight, and eggshell weight (Experiment 2). Effects on fertility may be related to higher female body weight during lay due to daylight rearing or added fat, or relative changes in light intensity at photostimulation.

Effect of overcooked soybean meal on turkey performance.

Three turkey growth experiments were conducted to evaluate the effect of overcooked soybean meal (SBM) on BW gain and gain:feed ratio (FE). On two occasions soybean meals were custom prepared by changing the temperature and the retention time (RT) of the desolventizer-toaster unit at a commercial soybean processing plant. Three different meals were produced for each occasion mainly by altering RT from normal to approximately 1.35 and 2.43 times normal operating conditions (designated SBM1 to 3 on the first occasion and SBM4 to 6 on the second occasion). For SBM1 to 6, urease activities were .06, .00, .20, .01 and .00 delta pH, protein solubilities in .1 M borate at 40 C were 44, 45, 16, 44, 32, and 24%, and protein solubilities in .2% KOH were 86, 84, 76, 90, 85, and 85%, respectively. In two sequential long-term experiments, SBM1 to 3 were fed to turkeys from 0 to 8 wk, then a control (normal processing conditions, SBMF), was fed to the all treatment groups from 8 to 12 wk of age. The SBM4 to 6 were fed from 12 to 18 wk of age after rerandomizing treatment allocation of replicate pens. In the first trial, poults fed SBM3 showed significantly reduced BW gain from 3 wk on and a lower FE shown at 9 wk. No difference in BW gain and FE was observed in the trial from 12 to 18 wk. In a 15-day, short-term experiment starting with 3-day-old poults and feeding diets containing SBM2 to 6, BW gain and FE did not differ among treatment groups. It is concluded that SBM did not show a detrimental effect on turkey growth until it was overcooked by 2.4 times the normal conditions. The usual operating conditions in a commercial processing plant are well within the range for producing adequate SBM for poultry feed.

Dietary threonine responses in growing turkey toms.

A study was conducted to evaluate Thr responses in Large White (British United Turkeys) male turkeys during three time periods: 0 to 3, 3 to 6, and 6 to 9 wk of age. The Thr-deficient diets, fed in 3-wk intervals, were composed primarily of corn, peanut meal, poultry meal, and soybean meal as intact protein sources and supplemented with amino acids. Graded levels of L-Thr were added to the Thr-deficient diets. Another group of turkeys received a corn-soybean-poultry meal control diet in each time period. Diets were formulated to meet a minimum of 110% of suggested amino acid specifications (NRC, 1994) for all essential amino acids, except Thr. Feed intake, BW gain, and feed:gain responses were measured. Average environmental temperatures for Weeks 1, 2, and 3 were 29, 27, and 24 C, respectively. From 4 to 9 wk of age, average environmental temperatures varied between 24 and 35 C. Turkeys in each time period responded to Thr in a curvilinear manner with responses at the asymptote being equivalent to turkeys fed the corn-soybean meal control diets. Adequate dietary Thr levels for gain and feed:gain for the 0 to 3 wk period were 0.93% (3.21 g Thr/Mcal ME) and 0.97% (3.34 g Thr/Mcal ME) of diet, respectively. From 3 to 6 wk of age, the level of dietary Thr needed to support adequate BW gain and feed:gain was 0.88% of diet (2.81 g Thr/Mcal ME). The level of dietary Thr needed to support adequate BW gain and feed:gain from 6 to 9 wk of age was 0.77% of diet (2.30 g Thr/Mcal ME). These results indicate that the NRC (1994) estimations of Thr needs up to 9 wk of age are more than adequate.

Potassium chloride improves the thermotolerance of chickens exposed to acute heat stress.

Experiments were designed to test the hypothesis that chicks that drank an electrolyte solution containing K prior to and during an acute exposure to heat would have greater thermotolerance than chicks that consumed only water. In three experiments, 5- or 7-wk-old male chickens drank distilled water (control), or .3, .6, or .9% KCl solutions (Experiments 1 and 2), and .6 or .9% KCl or .8% KHCO3 solutions (Experiment 3) for 48 h before acute heat stress (HS) and during HS. Body temperature (Tb), blood pH, partial pressure of blood carbon dioxide (pCO2), ionized Ca (Ca2+), plasma Na, K, Cl, total Ca, inorganic P (Pi), and osmolality (Osm), and water consumption were determined. Water intake increased with the concentration of KCl. Before HS, .6% KCl increased plasma K and Ca2+, whereas .9% KCl resulted in a marked increase in K, Ca2+, Na, Cl, and Osm and a decrease in pH. During HS, .6% KCl-birds had lower hyperthermic Tb and pH values and higher Ca2+ and K concentrations than controls. Plasma Na and Osm of .6% KCl birds decreased whereas those of the control birds remained unchanged. Providing K as KHCO3 aggravated respiratory alkalosis and failed to influence either Tb or plasma electrolytes, suggesting that the beneficial effect of .6% KCl may in part be attributed to the accompanying Cl. Hyperthermic Tb and Ca2+ values were highly correlated. The results showed that .6% KCl solution reduced HS-related responses and indicated a relationship among supplemental KCl, blood Ca2+, and Tb.