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Influence of dietary forage level and forage coarseness of grind on growth performance and digestive function in feedlot steers.

We conducted two trials to examine the influence of dietary forage level (FL; 16 and 8% sudangrass hay) and forage coarseness of grind (COG; ground to pass through a 2.5- vs 7.6-cm diameter screen) on growth performance and digestive function in feedlot steers fed a steam-flaked corn-based finishing diet. Thirty-two Mexican crossbred steers (297 kg) were used to determine treatment effects on growth performance during an 80-d finishing period. There were no treatment interactions (P > .10). Reducing FL increased (17%, P < .05) ADG. decreased (23%, P < .01) feed/gain, and increased (17% and 22%, P < .01) dietary NEm and NEg. Coarseness of grind did not affect (P > .10) steer performance. Treatment effects on digestive function were evaluated using four Holstein steers with cannulas in the rumen and proximal duodenum. There were no treatment interactions (P > .10) on nutrient digestibility. Forage level did not affect (P > .10) ruminal digestion of OM, N, or microbial efficiency. However, decreasing FL increased (P < .05) total tract digestion of OM (5.0%), N (5.7%), and ME (8.7%). Increasing COG increased total tract digestibility of OM (2.3%, P < .01), ADF (24.4%, P < .01); N (3.8%, P < .01), and ME (3.7%, P < .05). Increasing FL increased (P < .10) ruminal pH and decreased (P < .10) ruminal molar proportions of butyrate. Increasing COG did not influence (P > .10) ruminal pH or ruminal VFA molar proportions. We conclude that increasing coarseness of ground sudangrass may not improve the performance of feedlot steers when the forage is fed at either 8 or 16% of diet DM, although measures of ruminal and total tract nutrient digestibility may be slightly increased.

Animal Feed↗

Effects of dietary threonine and crude protein on growth performance, carcase and meat composition of broiler chickens.

1. The aim of the study was to investigate the effects of dietary threonine (Thr) and crude protein (CP) in maize-soybean meal based diets on the growth performance, carcase traits and meat composition of broiler chickens and to determine the dietary Thr requirement for optimum performance (weight gain and feed conversion efficiency (FCE)) at 0 to 3 weeks and 3 to 6 weeks of age. 2. Two basal diets that differed in CP (191.3 or 179.7 and 176.7 or 165.4 g/kg at 0 to 3 and 3 to 6 weeks, respectively) were formulated to have identical contents of Thr (6.0 and 5.4 g/kg), energy (12.97 and 13.39 MJ ME/kg) and other essential amino acids except for Gly + Ser. Basal diets were supplemented with L-Thr from 0.6 to 1.8 g/kg in 0.6 g/kg increments. Broiler chicks (540) were randomly allocated to 9 dietary treatments with 6 replicates of 10 (5 female, 5 male) chicks. 3. A significant interaction between dietary CP and Thr was found for feed intake, body weight (BW) gain and FCE. Increasing Thr supplementation improved feed intake, BW gain and FCE, especially in high CP diets in both feeding periods. 4. Incremental increases in dietary Thr increased breast yield at both CP levels and drumstick yield only on high CP diets. The proportion of thigh decreased with Thr concentration. Liver weight was significantly reduced by Thr supplementation; abdominal fat was not affected. 5. Estimated Thr requirements for FCE increased as dietary CP increased according to an exponential model. This model indicated higher Thr requirements than those of broken-line models for growth performance.

Aging↗

Effect of carbohydrate source on growth performance, carcass traits, and meat quality of growing-finishing pigs.

Two experiments were conducted to determine the effect of substituting a more available dietary carbohydrate (CHO) for portions of corn or fat in the diet on growth performance, carcass traits, meat quality, and serum or plasma metabolites in growing-finishing pigs. A three-phase feeding program was used with corn-soybean meal diets formulated to provide 105% of the Lys requirement for barrows or gilts gaining 325 g of lean daily in Exp. 1 or gilts gaining 350 g of lean daily in Exp. 2. Diets were isoenergetic within experiments. All other nutrients met or exceeded suggested requirements. In Exp. 1, pigs were allotted to three dietary treatments (0, 7.5, or 15.0% sucrose), with three replications of barrows and three replications of gilts, and with three or four pigs per replicate pen; average initial and final BW were 25.2 and 106.7 kg. In Exp. 2, gilts were allotted to two dietary treatments (waxy [high amylopectin] or nonwaxy [75% amylopectin and 25% amylose] corn as the grain source), with five replications of four gilts per replicate pen; average initial and final BW were 37.7 and 100.0 kg. In Exp. 1, ADG and gain:feed ratio increased linearly (P < 0.02) as dietary sucrose increased. Minolta color scores, a* and b*, and drip loss (P < 0.06) also increased linearly with added sucrose. In Exp. 2, ADG, carcass weight and length, and the Minolta a* value were greater for pigs fed waxy corn (P < 0.08) than for those fed nonwaxy corn. Feed intake, longissimus muscle area, 10th-rib and average backfat thickness, dressing percentage, fat-free lean, percentage of lean and muscling, lean gain per day, total fat, percentage fat, lean:fat ratio, serum or plasma metabolites (Exp. 1: serum urea N; Exp. 2: serum urea N, and plasma nonesterified fatty acids, triacylglycerols, total and high-density lipoprotein cholesterol, insulin, and total protein), pH of the longissimus muscle, and subjective muscle scores (color, firmness-wetness, and marbling) were not affected by diet in either experiment. In summary, increasing availability of dietary CHO in growing-finishing pig diets improved growth performance, but it did not affect carcass traits.

Adipose Tissue↗

Effects of modified tall oil and vitamin E on growth performance, carcass characteristics, and meat quality of growing-finishing pigs.

Crossbred barrows (n = 72) were used to evaluate effects of diet supplementation with modified tall oil (MTO; 0.0 or 0.50%) and vitamin E (0, 22, or 110 IU/kg) on growth performance, carcass traits, and longissimus muscle (LM) quality traits of finishing pigs. Pigs were blocked by ancestry and initial BW and allotted randomly to treatments in a 2 x 3 factorial. Corn-soybean meal-based diets were fed in two phases: 45.5 to 81.6 (1.00% lysine) and 81.6 to 114.6 (0.75% lysine) kg BW with no added fat. From 45.5 to 81.6 kg, pigs fed MTO had greater ADG (P = 0.03) regardless of added vitamin E; otherwise, treatment did not affect growth performance. Carcasses from pigs fed MTO had reduced (P < 0.05) average backfat (2.76 vs 2.92 cm) and firmer bellies compared to those fed no MTO. Boneless loins were cut into 2.54-cm chops at 7 d postmortem and evaluated for display color, thiobarbituric acid-reactive substance (TBARS), Warner-Bratzler shear force (WBSF), and sensory panel ratings. Visual color was similar (P > 0.05) among treatments at 0 and 1 d of display. At 4 and 6 d of display chops from pigs fed MTO with 110 IU vitamin E/kg had less deterioration (P < 0.05) than chops from pigs fed MTO with 0 IU vitamin E/kg and 0.0% MTO with 22 or 110 IU vitamin E/kg. The CIE L*, a*, b* and spectral values also suggested a delay in color deterioration for chops from pigs fed MTO with 110 IU vitamin E/kg. At 6 and 8 d of display, chops from pigs fed 110 IU vitamin E/kg had lower (P < 0.05) L* values than those from pigs fed 0 or 22 IU vitamin E/kg, and higher (P < 0.05) a* values than those from pigs fed 0 IU vitamin E/kg feed. A higher (P < 0.05) %R630/%R580 (indicator of more oxymyoglobin) was observed for chops from pigs fed MTO with 110 IU vitamin E/kg than those from pigs fed 0.0% MTO with 22 or 110 IU vitamin E/kg and MTO with 0 IU vitamin E/kg. Chops from pigs fed MTO with 110 IU vitamin E/kg had lower (P < 0.05) TBARS values than those from pigs fed MTO with 0 IU vitamin E/kg. No differences (P > 0.05) were detected among treatments for WBSF or sensory evaluations. The addition of MTO in swine diets improved belly firmness and reduced backfat, and feeding MTO with high levels of vitamin E extended display life without affecting palatability of LM chops.

Animal Feed↗

Effect of dietary energy source and immunological challenge on growth performance and immunological variables in growing pigs.

Forty-eight growing pigs (23 kg BW) were assigned to four treatments (n = 12) arranged as a 2 x 2 factorial. Dietary energy source (conventional [CON] vs high-oil corn [HOC]), with or without an immunological challenge (IC) regimen constituted main effects. The IC regimen consisted of injection of endotoxin (E. coli lipopolysaccharide [LPS]) and vaccination for porcine respiratory and reproductive syndrome (PRRS). Growth performance data were collected over a 5-wk period and are presented as prechallenge (d 1 to 14; d 1 was the 1st d of the study), challenge (d 15 to 21), and postchallenge (d 22 to 36) periods, and overall. Overall, the pigs fed HOC consumed less feed (P < .11) and gained more efficiently (P < .03). During the immunological challenge period, ADG was depressed 21% and feed intake 15% (P < .01). The IC resulted in lower (P < .01) serum alpha-1-acid glycoprotein (AGP) concentrations on d 22, and the magnitude of the reduction was greater in the pigs fed the CON diet (energy source x immune challenge, P < .10). Serum AGP concentrations remained lower (P < .08) in challenged pigs on d 36. Immunoreactive prostaglandin concentrations were higher (55%, P < .08) in the pigs fed HOC immediately following the IC period (d 22). The data reported herein indicate that the performance of pigs fed HOC is satisfactory, and that feeding HOC does not compromise growth performance during or after an immunological challenge.

Acute-Phase Proteins↗

Effect of a single injection of a long-acting gonadotropin-releasing hormone agonist on prepubertal male and female pigs on reproductive organs, growth performance and sensory qualities of pork roasts.

Crossbred pigs (n = 200) were used to study the effects of a long-acting form of gonadotropin-releasing hormone (GnRH) agonist on the reproductive systems of male and female pigs and their growth performance and sensory quality of pork roast. Treatment was a single injection of a controlled release formulation of GnRH agonist [D-Trp6, des-Gly10]-GnRH ethylamide to release 5 micrograms/(kg x day) for 4 months beginning when the pigs were 66 +/- 2 days old. Pigs were allocated to five groups of 40 animals each: males castrated (CM) at 13 +/- 2 days, intact males (IM), treated males (TM), intact females (IF) and treated females (TF). Ovarian and uterine weights at slaughter averaged 3.67 and 79.8 g, respectively, in IF compared with 1.38 and 26.5 g in TF (P < 0.05). Testicular weights were 203 g in IM and 36.8 g in TM (P < 0.05). Microscopic observations of the testes revealed an absence of sperm cells but the presence of germ cells. Steroid concentrations at slaughter from all pigs showed that intact males had significantly more testosterone in their serum (26.36 +/- 9.87 nmol/L) compared with TM, CM, IF or TF groups and that treated males had intermediate concentrations (12.50 +/- 7.44 nmol/L) higher (P < 0.05) than those in CM and TF. Administration of GnRH agonist during the growth period of male pigs had no consistent effect on growth performance, but as compared to IM pigs, some of the carcass characteristics such as meat ratio (49.1 vs 50.2% in TM and IM; P < 0.001), dressing percentage (77.5 vs 76.5% in TM and IM; P < 0.05) and average backfat (20.8 vs 17.6 mm in TM and IM; P < 0.05) were modified by such a treatment. Meat quality, however, as determined by flavor and tenderness evaluations by sensory panelists, were similar (P < 0.05) in all groups and off-flavor scores were lower in TM than in IM (P < 0.001). As for males, backfat and meat ratio were different in TF compared to IF (P < 0.05) and roast juiciness was higher in TF than IF (P < 0.05). These results suggest that GnRH agonist can reduce gonadal secretory activity to castration levels during the growth period of prepubertal male pigs and could be an alternative to surgical castration in the pork industry with no negative effects on growth and meat quality. No advantage to endocrine castration in females was found.

Animals↗

Effects of intramuscular injections of folic acid on serum folates, haematological status and growth performance of growing-finishing pigs.

In a first trial, 48 piglets aged 5 weeks, grouped into 6 blocks of 8 pigs each, were used to determine the effect of intramuscular injections of folic acid on serum folates, haematological status, growth performance and carcass characteristics. Each block consisted of 2 pens of 4 pigs; in one pen, pigs received, by weekly intramuscular injections, an increasing volume of a solution containing 5 mg/ml folic acid, while in the other the animals were non-injected controls. The concentration of serum folates in treated pigs was 19% higher (P = 0.005) than in controls. There was no effect of treatment (P greater than or equal to 0.29) on haemoglobin and haematocrit. During the starting period, (5-11 weeks) average daily gain was not influenced by folic acid injections but feed intake and feed conversion were decreased (P = 0.07 and P = 0.05 respectively). No effect of folic acid (P greater than or equal to 0.23) was noted from 11-23 weeks of age, suggesting that the supplement was suboptimal during the growing-finishing period. In a second trial, 72 piglets aged 9 weeks were assigned to 6 blocks of 12 animals each. The following treatments were randomly distributed in each block according to a 2 x 3 factorial design: level of feeding (restricted vs ad libitum) and weekly intramuscular injections of increasing volume of solutions containing either 0, 15 or 30 mg/ml of folic acid. The variables studied were the same as in Trial 1. Concentrations of serum folates varied quadratically (P = 0.0001) with the dose injected, a plateau being attained with injections of 15 mg/ml. There was no effect of treatment (P = 0.043) on haemoglobin and haematocrit. During the growing period (9-15 weeks), no effect (P greater than or equal to 0.72) of folic acid was noted on growth performance. However, during the finishing period (15-21 weeks), folic acid given at a dose of 30 mg/ml decreased (P = 0.006) feed intake while no effect (P greater than or equal to 0.13) of the vitamin supplementation was noted on average daily gain and feed conversion. In both trials, there was no effect (P greater than or equal to 0.21) of any treatments on carcass characteristics. These results indicate that a supplement of folic acid administered by intramuscular injections was effective in increasing concentration of serum folates of starting or growing-finishing pigs. This supplement may be associated with a decrease in feed intake.

Animal Feed↗

Effects of beta-mannanase addition to corn-soybean meal diets on growth performance, carcass traits, and nutrient digestibility of weanling and growing-finishing pigs.

Four experiments were conducted to determine the effects of adding a beta-mannanase preparation (Hemicell, ChemGen, Gaithersburg, MD) to corn-soybean meal-based diets on growth performance and nutrient digestibility of weanling and growing-finishing pigs. In Exp. 1, 156 weanling pigs (20 d, 6.27 kg BW) were allotted to four dietary treatments in a randomized complete block design. Treatments were a factorial arrangement of diet complexity (complex vs simple) and addition of 3-mannanase preparation (0 vs 0.05%). Pigs were fed in three dietary phases (Phase 1, d 0 to 14; Phase 2, d 14 to 28; and Phase 3, d 28 to 42). Pigs fed complex diets gained faster and were more efficient (P < 0.05) during Phase 1 compared with pigs fed simple diets. Overall, gain:feed ratio (G:F) tended to be improved (P < 0.10) for pigs fed complex diets and it was improved (P < 0.01) for those fed diets with beta-mannanase. In Exp. 2, 117 pigs (44 d, 13.62 kg BW) were allotted randomly to three dietary treatments. Dietary treatments were 1) a corn-soybean meal-based control, 2) the control diet with soybean oil added to increase metabolizable energy (ME) by 100 kcal/kg, and 3) the control diet with 0.05% beta-mannanase preparation. Beta-mannanase or soybean oil improved (P < 0.05) G:F compared with pigs fed the control diet. In Exp. 3, 60 pigs (22.5 kg BW) were allotted randomly to the three dietary treatments used in Exp. 2. Dietary treatments were fed in three phases (23 to 53 kg, 53 to 82 kg, and 82 to 109 kg with 0.95, 0.80, and 0.65% lysine, respectively). Overall, the addition of soybean oil tended to improve G:F (P < 0.10) compared with that of pigs fed the control diet, and G:F was similar (P > 0.54) for pigs fed diets with soybean oil or beta-mannanase. Also, addition of beta-mannanase increased ADG (P < 0.05) compared with that of pigs fed the control or soybean oil diets. There were no differences (P > or = 0.10) in longissimus muscle area or backfat; however, on a fat-free basis, pigs fed the diet with beta-mannanase had greater (P < 0.05) lean gain than pigs fed the control or soybean oil diets. In Exp. 4, 12 barrows (93 kg BW) were allotted randomly to one of the three dietary treatments used in Exp. 3. Addition of 3-mannanase had no effect (P > 0.10) on energy, nitrogen, phosphorus, or dry matter digestibility. These results suggest that beta-mannanase may improve growth performance in weanling and growing-finishing pigs but has minimal effects on nutrient digestibility.

Animal Feed↗

Effect of glutamine and spray-dried plasma on growth performance, small intestinal morphology, and immune responses of Escherichia coli K88+-challenged weaned pigs.

Forty weaned barrows (5.32 +/- 0.3 kg BW) at 17 +/- 2 d of age were used to investigate the effects of feeding glutamine and spray-dried plasma on the growth performance, small intestinal morphology, and immune responses of Escherichia coli K88-challenged pigs. Pigs were allotted to four treatments including: 1) nonchallenged control (NONC); 2) challenged control (CHAC); 3) 7% (as-fed basis) spray-dried plasma (SDP); and 4) 2% (as-fed basis) glutamine (GLN). On d 11 after weaning, all pigs were fitted with an indwelling jugular catheter. On d 12 after weaning, pigs in the CHAC, SDP, and GLN groups were orally challenged with skim milk E. coli K88 culture, whereas pigs in the NONC group were orally inoculated with sterilized skim milk. Rectal temperatures and fecal diarrheic scores were recorded and blood samples collected at 0 (baseline), 6, 12, 24, 36, and 48 h after the challenge for serum hormone and cytokine measurements. At 48 h postchallenge, all pigs were killed for evaluation of small intestinal morphology. There was no effect of feeding SDP or GLN on growth performance during the 11-d prechallenge period (P = 0.13). At 48 h after the challenge, CHAC pigs had decreased ADG (P = 0.08) and G:F (P = 0.07) compared with the NONC pigs; however, SDP and NONC pigs did not differ in G:F, and GLN and NONC pigs did not differ for ADG and G:F. At 6, 36, and 48 h after the challenge, CHAC, SDP, and GLN pigs had increased rectal temperature relative to the baseline (P = 0.09). At 12 and 36 h after the challenge, CHAC pigs had the highest incidence of diarrhea among treatments (P = 0.08). Serum IL-6 and ACTH were not affected by treatment or time after E. coli challenge (P = 0.11). In proximal, midjejunum, and ileum, CHAC pigs had greater villous atrophy and intestinal morphology disruption than NONC pigs (P < 0.01), whereas SDP and GLN pigs had mitigated villous atrophy and intestinal morphology impairment after E. coli challenge. Pigs in the SDP had the lowest GH at 12 h and the greatest GH at 36 h after the challenge among treatments (P = 0.08). Pigs in the NONC had the highest IGF-1 at 12 and 36 h postchallenge (P < 0.04). These results indicate that feeding glutamine has beneficial effects in alleviating growth depression of E. coli K88-challenged pigs, mainly via maintaining intestinal morphology and function, and/or possibly via modulating the somatotrophic axis.

Adrenocorticotropic Hormone↗

Effects of a Quillaja saponaria extract on growth performance and immune function of weanling pigs challenged with Salmonella typhimurium.

Ninety-six pigs (initially 8.9 kg and 24 d of age) were used in a 28-d experiment to determine the effects of Quillaja saponaria extract (QS) on weanling pig growth performance and immune function in response to enteric disease challenge with Salmonella typhimurium (ST). Experimental treatments were arranged in a 2 x 4 factorial with main effects of disease challenge (control vs ST-challenge) and dietary addition of QS (0, 125, 250, or 500 mg/kg). Pigs were fed QS diets for 14 d and then challenged orally with ST or sterile media. There were no differences in ADG or ADFI among dietary treatments, but gain/feed ratio (G/ F) was depressed (P < 0.06) in pigs fed 250 mg/kg QS. ST-challenge reduced ADG (P < 0.05), ADFI (P < 0.05), and G/F (P < 0.05) 1 wk after challenge. Daily estimates revealed reductions in feed intake in ST-infected pigs on d 2 to 5 following infection (P < 0.05), and rectal temperature was increased maximally 2 d following infection (P < 0.05). There was a marked decline in serum IGF-I during the 6 d after ST-infection (P < 0.05). ST-challenge produced a rise (P < 0.05) in serum haptoglobin on d 7 after challenge, and serum alpha1-acid glycoprotein (AGP) in ST-challenged pigs also was elevated (P < 0.05) above controls on d 7 and 14 after challenge. Serum immunoglobulin (Ig) M increased (P < 0.05) over time in both groups, and serum IgM of ST-challenged pigs was greater than controls on d 7 after challenge (P < 0.05). Serum IgG was not affected by enteric disease challenge; however, on d 7 and 14 after disease challenge, serum IgG for both groups was greater (P < 0.05) than on d 0. Dietary QS had no significant influence on any of the end points used to characterize the acute phase response to ST-challenge. Phagocytic cell function was depressed in pigs fed 250 (P < 0.05) and 500 (P < 0.05) mg/kg as compared to pigs fed 125 mg/kg QS. Yet, there was no difference in phagocytic function among pigs fed 0, 250, or 500 mg/kg QS. We conclude that this model of enteric disease invokes an acute phase response accompanied by decreases in feed intake and serum IGF-I. Furthermore, dietary QS, at the levels fed in this study, appears to offer little benefit to growth performance or immune function in the presence or absence of ST-challenge.

Acute-Phase Proteins↗

Effect of beta-mannanase (Hemicell) on growth performance and immunity of broilers.

Two hundred four broilers (1-d-old) were randomly allocated to 4 treatments, each of which had 3 pens of 17 chicks per pen and were used to investigate the effects of beta-mannanase (Hemicell) on growth performance and immunity. The chicks received the same basal diet based on corn-soybean meal and Hemicell was added to the basal diet at 0, 0.025, 0.05, and 0.075%, respectively. Weight of each replicate was determined at wk 0, 3, and 6 of age. There were no significant differences in average feed intake in the 0- to 3-wk and 0- to 6-wk periods, and no differences in serum IgA, or IgG concentrations. However, the addition of Hemicell significantly increased (P < 0.05) weight gain in the 4- to 6-wk and 0- to 6-wk periods. Feed conversion for the 0.025 and 0.05% groups was significantly greater (P < 0.05) than for the control group in the 4- to 6-wk and 0- to 6-wk periods. Hemicell significantly increased (P < 0.05) the serum IgM concentration in 3- and 6-wk-old broilers. Proliferation of T lymphocytes in 6-wk-old broilers for the 0.05% group was also improved (P < 0.05) significantly. The results indicate that Hemicell may improve growth performance and immunity of broilers.

Animal Feed↗

Growth performance and adipose tissue deposition in barrows fed n-methyl-D,L-aspartate.

We previously reported that broilers fed n-methyl-D,L-aspartate (NMA) exhibited enhanced feed conversion efficiency and decreased percentage of fat in carcasses. In this experiment, growth performance and backfat thickness were evaluated in barrows fed NMA. Poland China x Yorkshire barrows weighing 68.8 +/- 1.7 kg (mean +/- SE) were allowed ad libitum access to feed containing NMA at levels of either 0 (n = 7), 100 (n = 6), 200 (n = 8), or 300 (n = 8) mg/kg for 36 d. Barrows were slaughtered at 99.5 +/- 2.3 kg BW. There was no effect (P > 0.1) of NMA on ADG or feed consumption. Gain:feed ratio decreased (P < 0.03) in a linear fashion with increasing level of NMA. There was a cubic effect (P < 0.05) of NMA treatment on first-rib backfat thickness. In response to graded levels of NMA, backfat thickness at the 10th rib (P < 0.08) and last rib (P < 0.03) increased in a linear fashion. The NMA had no effect (P > 0.1) on backfat thickness measured at the lumbar vertebra or longissimus muscle area measured at the 10th rib interface. The percentage of lean in the carcass decreased in a linear fashion (P < 0.05) in response to increasing levels of NMA in the diet. In summary, NMA had an overall negative effect on growth performance and carcass yield characteristics in barrows. The dichotomous effects of NMA on feed efficiency and body composition in poultry and swine warrants further scrutiny.

Adipose Tissue↗

Effects of feeding combinations of steam-flaked grain sorghum and steam-flaked, high-moisture, or dry-rolled corn on growth performance and carcass characteristics in feedlot cattle.

The objective of these two feeding trials was to determine the associative effects of feeding steam-flaked grain sorghum (SFGS) in combination with steam-flaked (SFC), dry-rolled (DRC), or high-moisture (HMC) corn on growth performance and carcass characteristics in feedlot cattle. In Trial 1, 200 yearling heifers were blocked by weight, allotted to 25 pens, and fed one of five finishing diets (77% grain, 15% corn silage, and 8% supplement on a DM basis) for an average of 137 d. The grain combinations were 100:0, 75:25, 50:50, 25:75, and 0:100 SFC:SFGS, respectively. Treatment had no effect on DMI (P > .05), but ADG, gain efficiency, and final live and hot carcass weights decreased linearly (P < .05) as the proportion of SFGS increased in the diet. Carcass backfat, quality grade, and liver abscess score were not affected (P > .05) by treatment. In Trial 2, 306 yearling steers were blocked by weight, allotted to 30 pens, and fed diets that contained 74.5% grain, 10% corn silage, 7.5% soybean meal, 4% tallow, and 4% supplement (DM basis) for an average of 139 d. The grain and grain combinations were 100% DRC, HMC, SFC, or SFGS and a 67%:33% combination of SFGS: DRC or SFGS:HMC. For steers fed diets containing a single source of grain, those fed SFC gained 7% more live weight and had a 7% higher gain efficiency (P < .05) than those fed DRC or HMC. Growth performance of steers fed SFGS was intermediate. Feeding grain combinations (67% SFGS:33% HMC or DRC) resulted in a 5 to 6% positive associative effect (P < .05) for ADG and gain efficiency. Carcass characteristics were not affected (P > .05) by treatment. We concluded that there were significant benefits (positive associative effects) when SFGS was fed in combination with DRC or HMC, but the effects were smaller when SFGS was fed in combination with SFC.

Animal Feed↗

Effects of dietary glucogenic amino acid supplementation on growth performance, body composition and plasma free amino acid levels in genetically lean and fat chickens.

Two experiments were conducted to investigate the effects of pair-feeding, nutritional status (fasting vs feeding ad libitum) and supplementing diets with alanine (2 g/kg), threonine (2 g/kg), glutamic acid (5 g/kg) and arginine (5 g/kg) on growth performance, body composition and free plasma amino acid levels in genetically lean (LL) or fat (FL) chickens of 4 to 7 weeks of age. When fed ad libitum, FL chickens ate more than LL birds and showed higher lipid and protein gains. However, when pair-fed, FL birds exhibited increased lipid retention but lower protein gain. Growth performance and body composition were not significantly affected by the addition of glucogenic amino acids to the diets. However, amino acid supplementation slightly improved food to gain ratios but depressed gross energy and protein efficiencies in both lines. FL chickens had lower plasma levels of most glucogenic amino acids and higher levels of branched-chain and sulphur amino acids than LL birds, irrespective of diet and nutritional status. These results are discussed in relation to hormonal characteristics of FL and LL birds.

Amino Acids↗

Effect of gluconic acid on piglet growth performance, intestinal microflora, and intestinal wall morphology.

Gluconic acid (GA) derives from the incomplete oxidation of glucose by some Gluconobacter strains. When fed to nonruminant animals, GA is only poorly absorbed in the small intestine and is primarly fermented to butyric acid in the lower gut. This study investigated the effect of GA on in vitro growth response and metabolism of swine cecal microflora and on animal growth performance, intestinal wall morphology, and intestinal microflora. During a 24-h in vitro cecal fermentation, total gas production and maximum rate of gas production were increased by GA (linear, P < 0.001). Ammonia in cecal liquor was reduced by GA after 4, 8, and 24 h of fermentation (quadratic, P < 0.01). After 24 h of fermentation, total short-chain fatty acids, acetic acid, propionic acid, n-butyric acid, acetic to propionic acid ratio, and acetic + butyric to propionic acid ratio were linearly increased by GA (P < 0.001). In the in vivo study, 48 piglets were divided into 4 groups and housed in individual cages for 6 wk. Piglets received a basal diet with a) no addition (control) or with GA addition at b) 3,000 ppm, c) 6,000 ppm, or d) 12,000 ppm. After 6 wk, 4 animals per treatment were killed, and samples of intestinal content and mucosa were collected. Compared with control, GA tended to increase average daily gain (+13 and +14% for GA at 3,000 and 6,000 ppm, respectively; P of the model = 0.11; quadratic, P < 0.05). Daily feed consumption and gain to feed ratio were not influenced by GA. Intestinal counts of clostridia, enterobacteriaceae, and lactic acid bacteria were not affected by GA. Gluconic acid tended to increase total short-chain fatty acids in the jejunum (+174, +87, and +74% for GA at 3,000, 6,000, and 12,000 ppm, respectively; P of the model = 0.07; quadratic, P = 0.07). Morphological evaluation of intestinal mucosa from jejunum, ileum, and cecum did not show any significant differences among treatments. This study showed that feeding GA influences the composition and activity of the intestinal microflora and may improve growth performance of piglets after weaning.

Ammonia↗

Effect of long-term addition of folic acid on folate status, growth performance, puberty attainment, and reproductive capacity of gilts.

Three groups of 34 gilts received, from 9 wk of age until slaughter at 7 wk of gestation, diets supplemented with either 0, 5, or 15 mg/kg of folic acid. The concentration of serum folates increased linearly (P < or = .05) with the level of added folic acid. Although the growth performance was not influenced by the treatments during the overall growing period, feed intake (P < or = .10) and body weight gain (P < or = .05) from 17 to 21 wk of age increased linearly as folic acid level in the diet increased. Age and body weight at puberty as well as body weight gain during gestation were not influenced (P > or = .32) by treatments. Dietary folic acid addition did not affect (P > or = .21) either total weight and empty weight of uterine horns or ovarian total weight, stroma weight, and number and weights of corpora lutea. No treatment effect (P > or = .35) was observed on placental surface, number of placental areolae, litter size, fetus weight, or total litter weight or on fetal DNA, RNA, and protein. However, the concentration of folates in fetuses increased linearly (P < or = .03) with the addition of folic acid in the dam's diet. In conclusion, although a dietary addition of as high as 15 mg/kg of folic acid seemed to influence growth performance of gilts by the end of the growing period, it did not affect age at puberty.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗

Influence of floor space allowance and dietary selenium and zinc on growth performance, clinical pathology measurements and liver enzymes, and adrenal weights of weanling pigs.

Crossbred weanling pigs (n = 96, average initial weight, 8.4 kg) were used in a 6-wk trial using a 2 x 2 x 3 factorial arrangement of treatments to determine the effects of floor space allowance (.28 and .14 m2/pig), dietary Se (40 and 200 ppb), and dietary Zn (30, 80, and 250 ppm) on growth performance, clinical pathology measurements, serum minerals, and enzymes, liver enzymes, and adrenal weights. Pigs (four/pen) were given ad libitum access to feed and water. Body weight and feed consumed were recorded weekly, and heparinized blood samples were taken for the various assays. Three pigs per pen were killed at the end of the trial for gross examination of organs and tissues and for liver enzymes assays. Pigs housed with restricted floor space ate 21% less (P < .001) and grew 18% more slowly (P < .001) than pigs housed with adequate floor space, but their gain:feed ratio was 4% higher (P < .08). Growth performance was not influenced by dietary Se and Zn treatments. There was no mortality in any of the treatments, and no visible gross abnormalities in organs and tissues at necropsy examination, except that more musculoskeletal bruising was observed for pigs housed with adequate floor space. This finding is supported by higher serum K concentration and creatine phosphokinase activity for pigs housed with adequate floor space. Corticosteroid activity and adrenal weights were similar for all treatments. Concentrations of blood Se and glutathione peroxidase were positively related to dietary Se levels, and serum Zn concentration was related to dietary Zn levels. Other effects of dietary Se and Zn on clinical pathology measurements were minimal and usually unexplained. Most two-way interactions of Se and Zn with floor space allowance were nonsignificant, which suggests that the main effects of Se, Zn and floor space were independent. Some hematologic values, serum metabolites, serum minerals, and serum and liver enzymes were decreased or increased, which is suggestive of stress of pigs housed with restricted floor space. However, most values were unchanged, and a few changed in the direction to suggest benefits of restricting space; all values were within an expected normal range.

Adrenal Glands↗

Is polygyny a risk factor for poor growth performance among Tanzanian agropastoralists?

Anthropologists and demographers have devoted considerable attention to testing the fertility-polygyny hypothesis, which posits that polygynously married women have lower fertility than their monogamously married counterparts. Much less attention has been paid to the potential impact of polygynous marriages on the health and well-being of children. The objective of this paper was to assess whether polygynous marital status is a risk factor for poor nutritional status and growth performance among a cohort of young Tanzanian children. Using data collected from both wet and dry season periods, we tested for an association from both cross-sectional and longitudinal perspectives. Despite relatively high nutritional status compared to other agropastoralists and horticultural populations, as well as the presence of various socioecological factors that were expected to mitigate any "costs" to polygynous marriage, we found that among our target population, polygynous marital status is a risk factor for poor growth performance. This association is most pronounced in the wet season, and maintains even after allowing for the potential influences of child age and sex, and household characteristics. These results counter our original expectation, and suggest that polygyny is costly to children in this population; this does not appear to be the result of difference in early child environment or household wealth.

Age Factors↗