Concentrations of prolactin, luteinizing hormone and follicle stimulating hormone in pituitary and serum of horses: effect of sex, season and reproductive state

Pituitary and serum from 86 male or female horses of various reproductive states were collected in the normal breeding season (summer) and in the nonbreeding season (winter) at a commercial slaughterhouse. Concentrations of prolactin (PRL), luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured by radioimmunoassay. Concentrations of pregnant mare serum gonadotropin and reproductive steroids in serum and gross appearance of the reproductive tract and gonads were used to catagorize reproductive state. Concentrations of PRL were higher (P less than .01) in summer than in winter in pituitary and serum of mares, stallions and geldings. In summer, mares had higher (P less than .01) concentrations of PRL in serum than stallions. In mares, concentrations of LH in pituitary were higher (P less than .05) in summer than in winter. Concentrations of LH in serum were higher (P less than .01) in summer than in winter in mares and geldings, higher (P less than .01) in mares than in stallions in summer, higher (P less than .01) in geldings than in stallions in summer and higher (P less than .01) in mares with low serum progesterone (P) concentrations than in mares with high P concentrations in summer. Concentrations of FSH in pituitary and serum did not differ between summer and winter for any type of horse.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of Aspergillus oryzae fermentation extract on fermentation of amino acids, bermudagrass and starch by mixed ruminal microorganisms in vitro

The objective of this study was to examine the effects of Aspergillus oryzae fermentation extract (Amaferm) on the in vitro ruminal fermentation of coastal bermudagrass, soluble starch and amino acids. Mixed ruminal microorganisms were incubated in anaerobic media for either 24 h (Amaferm alone, soluble starch, amino acids) or 48 h (bermudagrass). Amaferm was added to the incubation bottles (n = 4) at concentrations of 0, .4 or 1.0 g/liter. When mixed ruminal microorganisms were incubated with only Amaferm, the 1.0 g/liter concentration increased the production of hydrogen (H2; P less than .001), methane (CH4; P less than .01), acetate (P less than .05), butyrate (P less than .01), total VFA (P less than .05) and NH3 (P less than .05). Addition of both levels of Amaferm to soluble-starch fermentations tended to enhance the production of H2 (P less than .11), CH4 (P less than .15), acetate (P less than .29) and total VFA (P less than .19); propionate production was increased (P less than .10) by 1.0 g/liter Amaferm, resulting in a decrease (P less than .05) in the acetate:propionate ratio. Fermentation of amino acids plus 1.0 g/liter Amaferm enhanced the production of acetate (P less than .05), propionate (P less than .05), valerate (P less than .01) and total VFA (P less than .10) and decreased the acetate:propionate ratio (P less than .05). In addition, NH3 production tended (P less than .19) to increase with both levels of Amaferm. When bermudagrass was the substrate, few changes in fermentation products were observed with Amaferm treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of prenatal androgenization on lamb performance, carcass composition and reproductive function

Two experiments were conducted in which pregnant crossbred ewes were randomly assigned to a control group or implanted with testosterone propionate/silastic implants between d 40 and d 60 of gestation. Implants contained approximately 2 g testosterone propionate and provided a constant delivery of 8.7 mg/d. Androgenized ewes (TE), born to implanted dams, had lower adjusted birth weights (P less than .05) than control ewes (CE) in both experiments. Treated rams (TR) also displayed lower birth weights than control rams (CR) in both experiments, but the difference was significant only in Exp. 2. Average daily gain was 16.4% more (P less than .05) for TE than for CE in Exp. 1. In Exp. 2, TE gained 9.6% faster (P less than .05) and had 14.6% (P less than .05) more weight per unit of feed consumed than CE. In both experiments, average daily gain and gain-to-feed ratio were similar for TR and CR. In Exp. 2, prenatal androgenization of ewes reduced (P less than .05) 12th rib fat thickness and decreased (P less than .05) percent kidney and pelvic fat. Yield grades of TE were lower than CE in both Exp. 1 (P less than .10) and Exp. 2 (P less than .05). From additional measurements taken in Exp. 2, liver weight per unit of carcass weight was greater (P less than .05), anogenital distance was greater (P less than .01) and test tube penetration into the vestibule was less (P less than .01) for TE than CE. The TE did not exhibit regular estrous cycles, while CE displayed recurring estrous cycles.     

Effect of active immunization against growth hormone-releasing factor on growth and onset of puberty in beef heifers.

Angus and Charolais heifers (195 +/- 7 kg) were actively immunized against growth hormone-releasing factor (GRF) to evaluate the effect on concentrations of somatotropin (ST), insulin-like growth factor I (IGF-I), insulin (INS), growth, and onset of puberty. Primary immunizations were given at 184 +/- 7 d of age (d 0 of experiment) by injecting (s.c.) 1.5 mg of GRF-(1-29)-Gly-Gly-Cys-NH2 conjugated to 1.5 mg of human serum albumin (GRFi, n = 22) or 1.5 mg of human serum albumin (HSAi, n = 21). Booster immunizations of .5 mg of antigen were given on d 62, 92, 153, and 251. Antibody binding (percentage at 1:2,000 dilution) to [125I]GRF on d 69 was greater (P less than .01) in GRFi (53.7 +/- 4.5) than in HSAi (10.1 +/- .6) heifers. Serum concentration (ng/ml) and frequency (peaks/5 h) of ST release, respectively, on d 78 were lower (P less than .01) in GRFi than in HSAi heifers (3.3 +/- .1 vs 5.6 +/- .2 and .9 +/- .3 vs 2.3 +/- .2). Serum IGF-I (ng/ml) was lower (P less than .01) in GRFi than in HSAi heifers on d 69 (41 +/- 5 vs 112 +/- 4). Serum INS (microU/ml) on d 78 was lower (P less than .05) in GRFi (2.2 +/- .1) than in HSAi (3.8 +/- .2) heifers. Feed intake, ADG, and feed efficiency were lower (P less than .05) in GRFi than in HSAi heifers. Hip height was lower (P less than .01) and fat thickness was greater (P less than .05) in GRFi than in HSAi heifers by d 132 and 167, respectively. Percentage of heifers attaining puberty (progesterone greater than 1 ng/ml for two consecutive weeks) by d 209 and 379 (12.9 and 18.5 mo of age), respectively, was lower (P less than .05) in GRFi (40.9 and 45.5) than in HSAi (81.0 and 100). In conclusion, growing heifers were successively immunized against GRF. Active immunization against GRF resulted in decreased serum concentration of ST, IGF-I, and INS. In addition, GRF immunization led to lowered feed intake, ADG, and feed efficiency, increased fat depth, and delayed onset of puberty in heifers. We propose that ST and IGF-I are important metabolic mediators involved in the initiation of puberty in heifers.     

The effect of pure and partial yellow endosperm sorghum grain hybrids on site and extent of digestion in beef steers

To compare the effects of sorghum grain hybrids on site and extent of digestion, two yellow (Y1 and Y2), two cream (C1 and C2), and two hetero-yellow (HY1 and HY2) sorghum grains were fed (1.85% BW, DM basis) in an 81% dry-rolled grain diet to steers (342 kg BW) equipped with ruminal, duodenal, and ileal cannulas within a 6 X 6 Latin square. Yellow (YEL) hybrids had a homozygous yellow endosperm and a yellow seed coat; cream (CREAM) and hetero-yellow (HET-YEL) hybrids had a heterozygous (partial) yellow endosperm, with white or red seed coats, respectively. Total tract starch digestibility (percentage) was greater (P less than .10) for CREAM and HET-YEL (82.3) than for YEL (78.9), primarily because of greater (P less than .05) starch digestion in the large intestine. Ruminal starch digestibility (percentage) was greater (P less than .10) for HET-YEL (73.2) than for CREAM (66.3) and was a larger proportion of total tract digestion for HET-YEL (90.6) than for CREAM (80.1). Ruminal starch digestion was correlated negatively (r = -.46; P less than .08) with ruminal escape of feed N. Prececal starch digestibility (average 76.2%) was more strongly correlated with ruminal digestibility (r = .69; P less than .01) than with digestion in the small intestine (r = .41; P = .12). Total tract nonammonia N (NAN) digestibility (percentage) was greater (P less than .10) for CREAM than for HET-YEL, greater for Y1 (P less than .10) than for Y2, greater for C2 (P less than .05) than for C1, and greater for HY2 (P less than .05) than for HY1. Flow of NAN to the duodenum was correlated negatively (r = -.55; P less than .05) with prececal starch digestion. Small intestinal NAN disappearance (g/d) was greater (P less than .01) for HY1 (76.0) than for HY2 (52.2). Microbial N flow (r = .88; P less than .01), but not feed N flow (r = .17; P = .52), to the duodenum was correlated with partial NAN digestibility in the small intestine. Hybrids differed in site and extent of digestion. Differences were generally larger for N than for starch.     

Effects of creep feeding, zeranol implants and breed type on beef production: II. Reproductive development and fat deposition in heifers

Effects of preweaning creep feeding and zeranol implants on reproductive tract development and udder and s.c. fat deposition were studied in 24 weanling heifers (7 mo of age) with Brahman and Romana Red sires and Angus and Angus x Brown Swiss F1 reciprocal crossbred dams. Creep treatment did not affect (P greater than .19) ovarian weight, ovarian size, uterine horn diameter or follicle number. Heifers from the three creep treatments did not differ (P greater than .25) in udder weight, total lipid or percentage of lipid in the udder. Noncreep-fed (NC) heifers had a greater (P less than .02) number of adipocytes/gram of udder tissue than did the long-term creep-fed (LC) and short-term creep-fed (SC) heifers. The LC heifers had larger udder (166.0 vs 152.7 m) and s.c. adipocytes (166.7 vs 148.8 m) than NC heifers. Heifers implanted with zeranol at 56 and 146 d of age had a greater (P less than .03) uterine horn diameter and heavier (P less than .02) uterine weight than unimplanted heifers. Percentage of lipid in the udder was lower (P less than .02) in heifers implanted with zeranol. Implanted heifers had smaller (P less than .10) s.c. adipocytes than unimplanted heifers. Breed of dam did not effect (P greater than .17) development of the reproductive tract of weanling heifers. Heifers from Angus dams had smaller (P less than .08) udders and less (P less than .10) total fat in the udder than those from F1 dams, and the heifers from F1 dams tended (P less than .12) to have larger udder adipocytes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Animal performance, plasma hormones and metabolites in Holstein and Belgian Blue growing-fattening bulls

Six Holstein (light-muscled type) and six Belgian Blue bulls (double-muscled type) were fed a finishing diet. Average daily gain was 1.36 kg for the Holstein bulls vs 1.24 kg for the Belgian Blue bulls (P less than .05). Holstein bulls consumed more feed (2.3 vs 1.8 kg/100 kg body weight, P less than .001) than the Belgian Blue bulls. The dressing percentage (55.4 vs 65.8%, P less than .001) and the proportion of muscle (56.1 vs 71.3%, P less than .001) in the carcass were less, whereas the proportions of adipose tissue (28.3 vs 15.4%, P less than .001) and bone (15.7 vs 13.4%, P less than .05) were higher in the Holstein bulls. Plasma creatinine determined in samples obtained once a week was lower (11.0 vs 20.3 mg/liter, P less than .001) in the Holstein bulls. In contrast, Holstein bulls tended to produce more triiodothyronine (2.3 vs 1.8 nM, P less than .10), tetraiodothyronine (71.9 vs 54.7 nM, P less than .10) and insulin-like growth factor I (IGF-I; 340 vs 205 ng/ml, P less than .20) than the Belgian Blue bulls. Growth hormone, insulin, IGF-I and testosterone were measured at 20-min intervals during two 24-h periods. In wk 6, Holstein bulls tended to produce more growth hormone than the Belgian Blues, as indicated by higher total peak area (3,185 vs 2,431 ng), peak amplitude (34.1 vs 22.6 ng/ml, P less than .10) and baseline (4.6 vs 3.3 ng/ml, P less than .20). In wk 27, the trends were opposite.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of steam-flaked, steamed-whole or whole shelled corn on performance and digestion in beef steers

Three trials were conducted to evaluate finishing diets containing 67% steam-flaked corn (SFC), steamed-whole corn (SWC) or whole corn (WC). In a feeding trial, steers fed SWC consumed more (P less than .05) dry matter per day (7.6 kg) than those fed WC (7.0 kg) or SFC (6.7 kg). Average daily gain was greater (P less than .05) for steers fed SFC (1.33 kg) and SWC (1.31 kg) than for those fed WC (1.25 kg), and feed efficiency was better (P less than .05) for steers fed SFC (5.06 kg dry matter/kg gain) than for those fed WC (5.62) and SWC (5.79). Carcass characteristics were not different among the three groups. In a digestion trial, method of corn processing did not affect digestibility of dry matter and crude protein. Starch digestibility was greater (P less than .05) for SFC (99.1%) than for SWC (93.8%) and WC (93.0%). There were no differences in nitrogen (N) intake or fecal N among the three diets; however, urinary N was less (P less than .05) for SWC (19 g/d) than for SFC (27 g/d) and WC (32 g/d), and N retention was higher (P less than .05) for the SWC diet. In vitro dry matter digestibility of the SFC diet was higher (P less than .05) than for WC at 4 and 8 h of incubation and higher (P less than .05) than the SWC diet at 8, 12 and 24 h of incubation. In vitro gas production after 6 h was greater (P less than .05) for SFC than for SWC grain, which was greater (P less than .05) than WC.(ABSTRACT TRUNCATED AT 250 WORDS)     

Conception rate in Bos taurus and Bos indicus crossbred heifers after postweaning energy manipulation and synchronization of estrus with melengestrol acetate and fenprostalene

Conception rate in heifers after synchronization of estrus with melengestrol acetate (MGA) and fenprostalene (a prostaglandin F2 alpha analogue; PGF) was determined in pubertal Bos taurus and Bos indicus crossbred yearling heifers. Angus x Hereford (AH, n = 137) and Brahman x Hereford (BH, n = 97) heifers were sorted by body weight after weaning into light (LW) and heavy (HW) weight blocks. Heifers were assigned by age to diets to reach a target weight of 55% (LE) or 65% (HE) of their projected mature weight by the start of breeding. Heifers that exhibited estrus and had serum progesterone greater than or equal to 1 ng/ml (0 or 10 d before estrous synchronization treatment) were assigned randomly within breed and nutritional groups to either an estrous synchronization (S) or control (C) group. Heifers in the S group were fed .5 mg of MGA for 7 d and injected s.c. with 2 mg PGF on d 7 of MGA. All heifers were inseminated 12 h after first detected estrus. A greater proportion of AH (P less than .01) than of BH heifers were in estrus within 6 d after PGF, and more S heifers than C heifers (P less than .01) were in estrus. Conception rate at first service was proportionately higher (P less than .001) in AH than in BH heifers and lower (P less than .02) in S than in C heifers. There was a breed x energy level interaction (P less than .01) for conception rate at first service. Stage of the estrous cycle at the time treatment with MGA was initiated influenced (P less than .05) conception rate at first service in the S, AH heifers, with lower conception rates among heifers beginning treatment late in their estrous cycles (greater than or equal to d 12). Pregnancy rates after 21 d were higher (P less than .01) in AH than in BH heifers and higher (P less than .01) in HW than in LW heifers. More HE than LE heifers (P less than .02), and more AH than BH heifers were pregnant after 45 d. Pregnancy rates at the end of 21 d were higher among HE, BH heifers than among LE contemporaries. A higher (P less than .02) percentage of HE, HW, BH heifers were pregnant at the end of 45 d compared with other BH groups. Results indicated that a 7-d MGA-PGF treatment reduced conception rates at first service in pubertal yearling heifers. Pregnancy rate was affected by prebreeding nutrition in BH yearling heifers at the end of 45 d.     

Effect of prenatal androgenization on growth performance and carcass characteristics of steers and heifers

Two experiments were conducted in which pregnant crossbred cows were randomly assigned to a control group or implanted with testosterone propionate/silastic implants between d 110 and 140 of gestation in Exp. 1 and between d 80 and 110 of gestation in Exp. 2. Androgenized heifers (TH) and treated steers (TS), born to implanted dams, possessed similar birth weights compared with control heifers (CH) and steers (CS), respectively, in both experiments. In Exp. 1, yield grades were lower (P less than .05) for TH than for CH. In Exp. 2, TH possessed 9.4% greater (P less than .07) 205-d adjusted weaning weights and 9.8% heavier (P less than .05) adjusted yearling weights than CH. In Exp. 2, daily gain was 19.5% faster (P less than .05) and feed intake was 13.6% greater (P less than .05) for TH than for CH. In Exp. 2, TH possessed less (P less than .05) s.c. fat, greater (P less than .10) carcass weight gains and lower (P less than .05) yield grades than CH. Liver weight per unit of carcass weight was greater (P less than .07) for TH than for CH in Exp. 2. Androgenized heifers had lower (P less than .07) lipid content in the 9-10-11th rib section than did CH. Calving intervals were similar for implanted and nonimplanted cows in both experiments. Results from these two trials suggest that efficiency of heifers for producing carcass beef can be improved by prenatal testosterone exposure.     

Effects of implanting ram and wether lambs with zeranol at birth and weaning on palatability and muscle collagen characteristics.

Thirty-five zeranol-implanted (I) and nonimplanted (NI) ram and wether lambs representing four treatments (implanted rams [IR], nonimplanted rams [NIR], implanted wethers [IW], and nonimplanted wethers [NIW]) were evaluated for meat palatability and muscle collagen characteristics. Rib (longissimus muscle, LM) chops from I lambs were juicier (P less than .05) than rib chops from NI lambs. Chops from IR lambs had more (P less than .05) detectable connective tissue and lower myofibrillar and overall tenderness scores than chops from NIR, IW, or NIW lambs. Warner-Bratzler shear (WBS) values tended to be higher (P = .06) for LM chops from rams than for those from wethers, but WBS values for Biceps femoris (BF) chops were similar (P greater than .05) for rams and wethers. Implanting did not affect (P greater than .05) WBS values. Rams had more (P less than .05) LM heat-labile (soluble, SC), nonheat-labile (insoluble, IC), and total collagen (TC) and a higher (P less than .05) percentage of SC (SC/TC) than did wethers. Soluble collagen, TC, and percentage of SC for the BF were higher (P less than .05) and IC tended (P = .09) to be higher in chops from rams than in those from wethers. Implanting did not affect (P greater than .05) collagen amount or solubility. Serum nonprotein hydroxyproline (NPHP) was higher (P less than .05) in rams than in wethers throughout the feeding period and tended (P = .05) to be higher at slaughter. Implanting did not affect (P greater than .05) serum NPHP.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of protein and energy supplementation of wheat straw-based diets on site of nutrient digestion and nitrogen metabolism of lambs.

A 4 x 4 Latin square metabolism trial with 2 x 2 factorial arrangement of treatments was conducted with lambs to determine effects of energy and CP supplementation of wheat straw-based (WS) diets on apparent N digestion, retention, and flow to the abomasum. Four wether lambs (average weight, 32 kg) fitted with ruminal and abomasal cannulas were fed 70 vs 42% WS (remainder of the diet was concentrate) and 9.5 vs 12.5% CP. Ruminal and total tract DM and OM digestion was 41 and 33% greater (P less than .03) for high-energy than for low-energy diets. Apparent N digestibility was greater (P less than .05) for 12.5% CP than for 9.5% CP diets (69.2 vs 62.0%, respectively) and also greater (P less than .03) for high-energy than for low-energy diets (67.4 vs 63.7%, respectively). High-energy diets resulted in a 23% greater (P less than .03) N retention (percentage of N intake) than did low-energy diets; 12.5% CP diets resulted in a 9% greater N retention (P less than .10) than did 9.5% CP diets. Nitrogen retention (percentage of N digested) was 15% higher (P less than .03) for high-energy than for low-energy diets. Protein level had no effect (P greater than .10). Nitrogen retention (grams/day) was 5.65, 6.97, 5.28, and 7.43 for low-energy, high-energy, low-protein, and high-protein diets, respectively; there were responses to energy level (P less than .03) and protein level (P less than .05). Total N flow (grams/day) to the abomasum did not differ (P greater than .10) due to treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of environmental temperature on growth, muscle and adipose tissue metabolism, and meat quality in swine.

An experiment involving 32 individually housed, castrated male pigs was conducted to determine the effects of environmental temperature (12 degrees C = T12 or 28 degrees C = T28) on the performance, carcass characteristics, muscle and adipose tissue metabolism, and meat quality of pigs fed to achieve equal rates of weight gain between 8 and 92 kg live weight. The T12 pigs had less muscle (P less than .01) and more subcutaneous fat (P less than .01) in the ham than did T28 animals. Thyroids and adrenals were heavier (P less than .01) in T12 than in T28 pigs. Percentage of type I muscle fibers was higher (P less than .01) and fiber cross-sectional areas smaller (P less than .01) in semispinalis muscle (SS) of T12 pigs, whereas no effect of temperature was noticed in longissimus muscle (LD). Cold exposure induced a larger increase in oxidative metabolism in SS (+30 to 32%, P less than .001) than in LD (+14 to 17%, P less than .10) and an enhanced glycolytic metabolism in LD (P less than .05). Lipid concentration was higher in SS of T12 than in that of T28 pigs. Lipogenic enzyme activities and unsaturation of backfat were higher in T12 than in T28 pigs, whereas no effect of temperature was noticed in leaf fat. Cold treatment resulted in a faster postmortem pH decline (P less than .01), higher glycolytic potential (P less than .01), and lower ultimate pH (P less than .01) in LD. The results indicate that 12 degrees C vs 28 degrees C induced detrimental effects on growth, ham composition, and muscle and adipose tissue quality.     

Growth, carcass traits, boar odor and testicular and endocrine functions of male pigs fed a progestogen, altrenogest

Crossbred (Chester White X Yorkshire X Duroc) boars were used to evaluate the effects of feeding a progestogen (altrenogest) on body growth, endocrine function (determined during feeding and after withdrawal of altrenogest), carcass composition, boar odor and testicular function (determined after a 30-d withdrawal from altrenogest). Boars from 18 litters were assigned at 12 wk of age to three treatments: 1) 18 control boars; 2) 18 boars fed altrenogest (20 mg/day) for 6 wk from 15 to 21 wk of age, followed by 30 d with no treatment; and 3) 18 boars castrated at 2 wk of age (barrows). Daily gains were greater (P less than .05) in boars fed altrenogest than in barrows through 21 wk of age but were lower (P less than .05) than those of control boars and barrows during the 30-d withdrawal period. Boars fed altrenogest weighed less (P less than .05) than control boars and barrows at 25 wk of age (at slaughter). Both groups of boars were similar in percentage of muscle and had less (P less than .05) backfat than barrows, whereas control boars had the largest (P less than .05) loineye areas. Based on evaluations by a trained sensory panel, intensity of boar odor in fat samples was similar for both groups of boars and was greater (P less than .05) than that for barrows. Weights of accessory reproductive glands and weight and sperm content of testes and epididymides were reduced (P less than .05) in boars fed altrenogest.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of dairy food processing wash water solids as a protein source: II. Microbial protein synthesis, duodenal nitrogen flow, and small intestinal amino acid disappearance

Twelve ruminally, duodenally, and ileally-cannulated Hereford heifers (average initial BW 313 +/- 20 kg) were used in a replicated experiment to evaluate dairy food processing wash water solids (WWS) as a protein source. Heifers were fed 2.8 kg of chopped (7.6 cm) hay and one of three supplements (1.5 kg/d, DM basis). Supplements were formulated to be similar in energy and contained 1.0 (control), 23.2 (WWS), and 21.6% (soybean meal; SBM) CP on an OM basis. Total N and nonammonia N entering the duodenum (g/d) were greater (P less than .10) for heifers fed WWS and SBM supplements than for controls. Bacterial N flow (g/d) at the duodenum was less (P less than .10) for controls (43.9) than for WWS- (63.9) and SBM- (69.9) supplemented heifers. Feed escape N (g/d) was greater (P less than .10) for WWS-fed heifers than for those fed SBM (32.1 vs 20.7 g/d, respectively). Total tract N digestion (g/d) was greatest (P less than .10) for SBM, intermediate for WWS, and least for control heifers. Microbial protein synthesis (g/kg of OM intake) was enhanced (P less than .10) by WWS and SBM supplementation, but efficiency of synthesis (g/kg of OM fermented) did not differ among treatments. Essential amino acid (AA) disappearance in the small intestine (g/d) was less (P less than .10) for control than for the other two treatments. Nonessential AA disappearance was greatest (P less than .10) for the WWS and least (P less than .10) for the control treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of dietary protein level on nitrogen metabolism in lambs: studies using 15N-nitrogen

Six wether lambs (31 kg) were randomly assigned to two treatments (three lambs/treatment): a high protein intake (HP; 21 g N/d) or a low protein intake (LP; 12 g N/d). Each lamb received 860 g/d dry matter (DM) of a pelleted diet (75% corn-soybean meal, 25% cottonseed hulls) offered hourly in 24 equal portions. Single injections of 15N-labelled compounds were made into the ruminal NH3-N and blood urea-N pools to measure the rate of flux through, and transfer of N between, these and the bacterial N pool. Total tract digestibilities of DM and N were lower (P less than .05) for the LP than the HP treatment. Abomasal flows of total, feed or bacterial N tended to be greater (P greater than .05) in lambs fed HP than LP. Lambs fed HP excreted more (P less than .01) urinary N, yet retained a greater (P less than .01) amount of N than lambs fed LP (6.2 vs 1.8 and 9.7 vs 4.1 g N/d, respectively). Pool size and production rate for both ruminal NH3-N and blood urea-N were greater (P less than .05) for the HP than LP treatment. Lambs consuming HP degraded more (P less than .05) blood urea-N in the gastro-intestinal tract (13.4 vs 6.9 g N/d); however, lambs fed LP degraded a greater (P less than .05) percentage of synthesized body urea-N (88.7 vs 71.8%). Ruminal NH3-N absorption was greater (P less than .01) for the HP than LP treatment (3.1 vs .5 g N/d). Although the percentage of bacterial N derived from ruminal NH3-N was similar (P greater than .05) between diets (51.1 vs 63.9), a greater (P less than .05) percentage of bacterial N was derived from blood urea-N in lambs fed LP than HP (77.1 vs 30.2%). Lambs fed LP incorporated a greater (P less than .10) amount of blood urea-N into bacterial N than lambs fed HP (5.5 vs 2.6 g N/d). These data are interpreted to suggest that blood urea-N may provide a substantial quantity of N for bacterial protein synthesis and, thus, may be an important source of protein in the deficient animal. In addition, urea recycling may play an important role in the recovery of ruminal NH3-N lost through absorption in animals fed a high level of protein.     

Effect of protein and energy intake by primiparous sows during lactation on sow and litter performance and sow serum thyroxine and urea concentrations

The effects of protein and energy intakes by primiparous sows during a 28-d lactation on thyroxine (T4) and urea concentrations in blood serum of sows, and sow and litter performance were examined in two experiments. Dietary treatments were protein intakes of 380 (LP) and 760 (HP) g of crude protein X sow-1 X d-1 and energy intakes of 8 (LE) and 16 (HE) Mcal of metabolizable energy (ME) X sow-1 X d-1 in a 2 X 2 factorial arrangement. In Exp. 1 (34 sows), neither protein nor energy intake affected serum T4 concentrations. In both experiments, serum urea concentrations during lactation were influenced by both protein (P less than .001) and energy (P less than .001) intakes. In Exp. 2 (221 sows), sows fed LP or LE lost more weight (P less than .001) during lactation than sows fed either HP or HE. Backfat loss was greater (P less than .001) in sows fed diets of LE than HE, whereas sows fed HP lost more backfat (P = .016) than sows fed LP. Pig weights on d 28 were influenced by both protein (P less than .001) and energy (P = .038), with sows that were provided high intakes of either protein or energy having heavier pigs. Litter weight at weaning was heavier (P less than .005) for sows consuming HP. Sows fed LP had larger litters at d 14 (P = .051) and 28 (P = .046) than sows fed HP. Sow energy intake had no effect on litter size or weight. Percentages of sows in estrus by 7, 14 and 35 d postweaning were higher (P less than .004, P less than .030 and P less than .060, respectively) for sows fed HP than LP, whereas sow energy intakes had no effect on the interval from weaning to first estrus.     

Influence of dietary energy intake on prepubertal development of Brahman bulls

Twelve Brahman bulls (paired by sire, weight and age) were assigned randomly and limit fed to gain either .10 to .25 (moderate gain; MG) or .75 to 1.0 (high gain: HG) kg.hd-1.d-1 to examine the effect of dietary energy on onset of puberty. Hip height (HH), scrotal circumference (SC) and serum samples (20 min for 6 h) were obtained at four times (AGE): 0, 56 and 112 d on feed and after appearance of first motile spermatozoa (FS) in the ejaculate of HG bull of the pair. At FS both bulls of a pair were slaughtered, reproductive tissues were collected and in vitro GnRH release from the median eminence (ME) was measured. Increases in BW, HH and SC were greater (P less than .05) in HG bulls. Basal ME GnRH secretion was greater (P less than .05) in HG bulls. Serum LH concentrations were unchanged by energy level (P greater than .10) but increased (P less than .01) with increasing AGE. AGE and energy level increased (P less than .01) basal, mean and total serum testosterone (T) and these two factors acted synergistically (P less than .01). Height and amplitude of T pulses were increased by energy level (P less than .003) and AGE (P less than .002). Testicular T (P less than .08) and development (P less than .05) were increased in HG bulls. Growth hormone peak height and amplitude concentrations following feeding increased with AGE (P less than .06) but were not altered (P greater than .10) by energy level. Serum triglycerides (P less than .03) and BUN (P less than .003) increased with increasing AGE (P greater than .01). These data indicate that dietary energy level influences onset of puberty most directly at the testicular level.     

Influence of grain and monensin supplementation on ruminal fermentation, intake, digesta kinetics and incidence and severity of frothy bloat in steers grazing winter wheat pastures

Three 10-d collection periods (April 4 to 14, early April, EApr; April 23 to May 3, late April, LApr; May 10 to 20, 1984, mid-May, MMay) were conducted to evaluate effects of no supplement (C), .5 kg-head-1.d-1 (as-fed basis) supplemental grain (steam-flaked milo, G) or G plus 170 mg monensin.head-1.d-1 (M) on forage intake and digestion by 12 ruminally cannulated beef steers (four/treatment; avg initially BW = 393 kg) grazing irrigated winter wheat pasture. Ruminal pH was greater (P less than .01) for M than for C or G during EApr but was not altered by treatments in LApr or MMay. Compared with C, ruminal NH3 was decreased (P less than .10) by G and M (5 h after supplementation) in EApr, decreased (P less than .05) by G (2h) and increased (P less than .05) by M (8 h) in LApr and decreased (P less than .10) by G (-1h) in MMay. Treatments had little influence on total VFA concentrations or on molar proportions of acetate and propionate. Butyrate molar proportion was decreased (P less than .10) by M during EApr and LApr, but not during MMay. Monensin increased (P less than .05) fluid passage rate compared with C and G in EApr but not in other periods, Particulate passage measurements did not differ (P greater than .10) among treatments within periods. Forage DM intake was not influenced (P greater than .10) by supplementation during any period. Extent of in situ forage DM disappearance was greater (P less than .10) for M than for C or G during EApr (12 and 30 h of incubation) but was not different (P greater than .10) in LApr or MMay. Incidence of frothy bloat was decreased (P less than .05) by M during EApr; this reduction may have been related to effects of M on ruminal pH, forage digestion and fluid passage.     

Effects of recombinant DNA-derived somatotropin and dietary energy intake on development of beef heifers: I. Growth and puberty

The effects of dietary energy intake and somatotropin (STH) on growth and puberty were studied in 40 Angus heifers. At an average age of 7 mo (208 +/- 8 d), heifers were assigned to four treatment groups: 1) vehicle (V) + high energy (HE; 2.68 Mcal ME/kg DM), 2) recombinant DNA-derived STH (20.6 mg/d; s.c.) + HE, 3) V + low energy (LE; 2.22 Mcal ME/kg DM) or 4) STH + LE. Animals remained on treatments until 15.5 mo of age. Body weights (BW), hip heights (HH) and areas of pelvic openings (PA) were measured every 28 d and backfat thicknesses (BF) were measured every 56 d. Plasma progesterone was measured in blood samples taken three times per week beginning at 9 mo of age to determine age at first ovulation. Heifers fed HE were heavier (P less than .01), gained faster (P less than .01) and had greater BF (P less than .01) than those fed LE. Animals treated with STH gained faster (P less than .01) and were heavier (P less than .05) between 12 and 15 mo of age than V-treated heifers. Heifers treated with STH also had less BF (P less than .05) and a tendency for a greater (P = .08) increase in HH than in V-treated heifers. Somatotropin interacted with energy (P less than .05) and age (P less than .01) to influence PA. Somatotropin increased (P less than .01) PA in heifers fed the HE diet but not in those fed the LE diet.(ABSTRACT TRUNCATED AT 250 WORDS)