Manure composition of swine as affected by dietary protein and cellulose concentrations

An experiment was conducted to investigate the effects of reducing dietary CP and increasing dietary cellulose concentrations on manure DM, C, N, S, VFA, indole, and phenol concentrations. Twenty-two pigs (105 kg initial BW) were fed diets containing either 14.5 or 12.0% CP, in combination with either 2.5 or 8.7% cellulose. Pigs were fed twice daily over the 56-d study, with feed intake averaging 2.74 kg/d. Feces and urine were collected after each feeding and added to the manure storage containers. Manure storage containers were designed to provide a similar unit area per animal as found in industry (7,393 cm2). Before sampling on d 56, the manure was gently stirred to obtain a representative sample for subsequent analyses. An interaction of dietary CP and cellulose was observed for manure acetic acid concentration, in that decreasing CP lowered acetic acid in pigs fed standard levels of cellulose but increased acetic acid in pigs fed greater levels of cellulose (P = 0.03). No other interactions were noted. Decreasing dietary CP reduced manure pH (P = 0.01), NH4 (P = 0.01), isovaleric acid (P = 0.06), phenol (P = 0.05), and 4-ethyl phenol (P = 0.02) concentrations. Increasing dietary cellulose decreased pH (P = 0.01) and NH4 (P = 0.07) concentration but increased manure C (P = 0.03), propionic acid (P = 0.01), butyric acid (P = 0.03), and cresol (P = 0.09) concentrations in the manure. Increasing dietary cellulose also increased manure DM (P = 0.11), N (P = 0.11), and C (P = 0.02) contents as a percentage of nutrient intake. Neither cellulose nor CP level of the diet affected manure S composition or output as a percentage of S intake. Headspace N2O concentration was increased by decreasing dietary CP (P = 0.03) or by increasing dietary cellulose (P = 0.05). Neither dietary CP nor cellulose affected headspace concentration of CH4. This study demonstrates that diets differing in CP and cellulose content can significantly impact manure composition and concentrations of VFA, phenol, and indole, and headspace concentrations of N(2)O, which may thereby affect the environmental impact of livestock production on soil, air, and water.     

Bone strength of caged layers as affected by dietary calcium and phosphorus concentrations, reconditioning, and ash content

1. The effects of preconditioning, dietary calcium and phosphorus concentrations, ash content, body weight, and bone geometry on the shear strength of the radius of caged layers were investigated. 2. Birds that did not lay for three or more weeks before the end of the production period had higher radius bone strengths than the birds producing eggs. 3. Shear breaking force increased with bone ash content. 4. The shear breaking force and stress of the radius were not affected by increasing dietary calcium and phosphorus during the last 8 weeks of production. 5. Freezing and thawing before testing had no effect on bone strength. 6. Body weight cannot be used to predict the breaking force of the radius of caged layers.     

Disappearance and appearance of an indigestible marker in feces from growing pigs as affected by previous-and currentdiet composition

Background: Indigestible markers are commonly utilized in digestion studies, but the complete disappearance or maximum appearance of a marker in feces can be affected by diet composition, feed intake, or an animal's BW.The objectives of this study were to determine the impact of previous(Phase 1, P1) and current-(Phase 2, P2)diet composition on marker disappearance(Cr) and appearance(Ti) in pigs fed 3 diets differing in NDF content.Results: When pigs were maintained on the 25.1, 72.5, and 125.0 g/kg NDF diets, it took 5.1, 4.1, and 2.5 d, respectively,for Cr levels to decrease below the limit of quantitation; or 4.6, 3.7, or 2.8 d, respectively, for Ti to be maximized. These effects were not, however, independent of the previous diet as indicated by the interaction between P1 and P2 diets on fecal marker concentrations(P 0.01). When dietary NDF increased from P1 to P2, it took less time for fecal Cr to decrease or fecal Ti to be maximized(an average of 2.5 d), than if NDF decreased from P1 to P2 where it took longer for fecal Cr to decrease or fecal Ti to be maximized(an average of 3.4 d).Conclusions: Because of the wide range in excretion times reported in the literature and improved laboratory methods for elemental detection, the data suggests that caution must be taken in considering dietary fiber concentrations of the past and currently fed diets so that no previous dietary marker addition remains in the digestive tract or feces such that a smal amount of maker is present to confound subsequent experimental results, and that marker concentration have stabilized when these samples are col ected.     

Response to dietary phosphorus deficiency is affected by genetic background in growing pigs

Concern over the environmental effect of P excretion from pig production has led to reduced dietary P supplementation. To examine how genetics influence P utilization, 94 gilts sired by 2 genetic lines (PIC337 and PIC280) were housed individually and fed either a P-adequate diet (PA) or a 20% P-deficient diet (PD) for 14 wk. Initially and monthly, blood samples were collected and BW recorded after an overnight fast. Growth performance and plasma indicators of P status were determined monthly. At the end of the trial, carcass traits, meat quality, bone strength, and ash percentage were determined. Pigs fed the PD diet had decreased (P < 0.05) plasma P concentrations and poorer G:F (P < 0.05) over the length of the trial. After 4 wk on trial, pigs fed the PD diet had increased (P < 0.05) plasma 1,25(OH)(2)D(3) and decreased (P < 0.05) plasma parathyroid hormone compared with those fed the PA diet. At the end of the trial, pigs fed the PD diet had decreased (P < 0.05) BW, HCW, and percentage fat-free lean and tended to have decreased LM area (P = 0.06) and marbling (P = 0.09) and greater (P = 0.12) 10th-rib backfat than pigs fed the PA diet. Additionally, animals fed the PD diet had weaker bones and also decreased (P < 0.05) ash percentage and increased (P < 0.05) concentrations of 1alpha-hydroxylase and parathyroid hormone receptor mRNA in kidney tissue. Regardless of dietary treatment, PIC337-sired pigs consumed more feed and gained more BW than their PIC280-sired counterparts (P < 0.05) during the study. The PIC337-sired pigs also had greater (P < 0.05) HCW, larger (P < 0.01) LM area, and tended to have (P = 0.07) greater dressing percentage. Meat from the PIC337-sired pigs also tended to have greater (P = 0.12) concentrations of lactate but decreased (P = 0.07) concentrations of total glucose units 24 h postslaughter. Although plasma 1,25(OH)(2)D(3) concentrations were elevated (P < 0.05) in all the animals fed the PD diet, this elevation due to P deficiency tended (P = 0.09) to be greater in the PIC337-sired pigs after 12 wk on the treatment. The PIC337-sired pigs had stronger (P < 0.01) bones with greater ash percentage than the PIC280-sired pigs. The difference in the strength of the radii between the PIC337-sired pigs fed the PA and PD diets was greater than their PIC280-sired counterparts, which resulted in sire line x treatment interactions (P < 0.05). These data indicate differing mechanisms of P utilization between these genetic lines. Elucidating these mechanisms may lead to strategies to increase efficiency of growth in a more environmentally friendly manner.     

Influence of myristic acid supplementation on energy, fatty acid and calcium metabolism of sheep as affected by dietary calcium and forage : concentrate ratio

In a 6 x 6 Latin square arrangement, sheep of 41 kg body weight were fed myristic acid [C14:0; 50 g/kg dry matter (DM)] supplemented to two basal diets of forage : concentrate ratios of 1 : 1.5 and 1 : 0.5 and adjusted to dietary calcium (Ca) contents of either 4.2 or 9.0 g/kg DM (the latter only together with C14:0 supplementation). Various variables of energy, fatty acid and Ca metabolism were determined in combined digestibility and respiratory chamber measurements. With C14:0 addition the energy loss via the faeces increased (p < 0.05, post hoc test) without affecting energy digestibility of the complete diet. The apparent digestibility of supplemented C14:0 was higher (p < 0.01) with approximately 0.8 in the forage-based diet than in the concentrate-based diet (approximately 0.6). The elevated levels of plasma C14:0 were mainly accompanied by reduced C18:0 and C18:1 levels. The estimated apparent content of metabolizable energy (ME) of added C14:0 was either 24.5 MJ/kg (concentrate-based diet) or 32.1 MJ/kg (forage-based diet). Extra Ca equalized these differences between basal diets and ME contents amounted to 33.0 MJ/kg on average. As expected from corresponding slight shifts in energy metabolizability, the total efficiency of ME utilization increased (p < 0.1) with C14:0. The lower level of dietary Ca was still within the range recommended, but adding C14:0 to the concentrate-based diet reduced Ca retention in the body of the sheep from 0.9 to -0.1 g/day because of an impaired (p < 0.05, post hoc test) net Ca absorption, whereas no effect was found with the forage-based diet. With C14:0 addition, plasma total phosphorus (P) and serum calcitrol levels increased (p < 0.05, post hoc test) while Ca concentrations did not clearly reflect the reduced net Ca absorption. Increasing the dietary Ca content prevented adverse effects on Ca retention in the concentrate-based diet and improved Ca retention in the forage-based diet. In conclusion, the C14:0 supplementation reduced Ca availability in concentrate-based diets while an additional supply of Ca improved Ca and energy retention. Consequently, Ca supply should exceed recommended levels in diet types where dietary lipids are likely to reduce Ca availability and a compromise in basal diet type has to found to be able to profit best from the energetic value and the methane-suppressing properties of C14:0.     

Fertility,hatghability and malformations in guinea fowl embryos as affected by dietary manganese

1. The effects of feeding diets containing 54 mg, 60 mg, 65 mg or 70 mg manganese/kg to Guinea fowls on fertility, hatchability and the occurrence of malformed embryos were studied.

2. Dietary manganese affected fertility slightly, but significantly affected hatchability and the occurrence of malformed embryos.

3. Hatchability was most significantly depressed at the lowest dietary concentration of manganese, which also caused a highly significant increase in the proportion of malformed embryos.

4. Although increasing manganese to more than 54 mg/kg improved hatchability and reduced embryonic malformations, the increase did not completely eliminate the latter condition.     

Performance, digesta characteristics, nutrient flux, plasma composition, and organ weight in pigs as affected by dietary cation anion difference and nonstarch polysaccharide

Two dietary cation anion difference (CAD) levels (-100 and 200 mEq/kg) and two dietary nonstarch polysaccharide (NSP) levels (10 and 15%) were used in a 2 x 2 factorial arrangement in two randomized blocks (trials) to evaluate performance, digesta pH and buffer capacity, apparent digestibility, plasma composition, and organ weight in pigs. Seven pigs with a mean initial weight of 7.5 kg were used in each treatment. Pigs had free access to feed and water during the 3-wk experimental period. At the end of the experiment, all pigs were killed approximately 2.5 h after addition of fresh feed. Liver, kidneys, and small and large intestine were removed and weighed immediately. Gastric and small intestinal (divided into two equal parts) digesta were collected. Dry matter, pH, buffering capacity, viscosity, acid insoluble ash, mineral content (Na+, K+, and Cl-), nitrogen, and gross energy content (only in the second part of the small intestine) of the digesta were measured. An interaction (P < 0.05) between dietary CAD and dietary NSP was observed for feed intake, growth, apparent digestibility of DM and gross energy in the distal small intestine, and chloride in the stomach and duodeno-jejunal part of the small intestine. Increasing dietary NSP content increased apparent digestibility of DM and chloride in the stomach and increased apparent digestibility of DM, chloride, sodium, and potassium in the first part of the small intestine. Lowering dietary CAD levels significantly increased apparent digestibility of DM in the first part of the small intestine and decreased chloride influx in the stomach and the small intestine. No significant differences were found for pH, buffering capacity, and viscosity of digesta, except the buffering capacity in the second part of the small intestine, which was higher (P < 0.05) in the 200 mEq/kg CAD group than in the -100 CAD mEq/ kg group. Plasma urea decreased in the low dietary CAD groups and plasma ammonia increased in the high NSP groups. Large intestine weight was significantly less for the -100 mEq/kg CAD groups than for the 200 mEq/kg CAD groups. In conclusion, the effect of CAD on feed intake and growth in pigs depends on dietary NSP levels.     

The effects of calcium benzoate in diets with or without organic acids on dietary buffering capacity, apparent digestibility, retention of nutrients, and manure characteristics in swine

Eight barrows (Yorkshire x [Finnish Landrace x Dutch Landrace]), initially 30 kg BW, were fitted with ileal cannulas to evaluate the effects of supplementing Ca benzoate (2.4%) and organic acids (OA) in the amount of 300 mEq acid/kg feed on dietary buffering capacity (BC), apparent digestibility and retention of nutrients, and manure characteristics. Swine were allotted in a 2 x 4 factorial arrangement of treatments according to a cyclic (8 x 5) changeover design. Two tapioca-corn-soybean meal-based diets were formulated without and with acidogenic Ca benzoate. Each diet was fed in combination with OA (none, formic, fumaric, or n-butyric acid). Daily rations were equal to 2.8 x maintenance requirement (418 kJ ME/BW(.75)) and were given in two portions. Chromic oxide (.25 g/kg) was used as a marker. On average, Ca benzoate lowered BC by 54 mEq/kg feed. This salt enhanced (P < .05) the ileal digestibility (ID) of DM, OM, arginine, isoleucine, leucine, phenylalanine, alanine, aspartic acid, and tyrosine (by up to 2.4 percentage units). Also, the total tract digestibility (TD) of DM, ash, Ca and GE, and Ca retention (percentage of intake) was greater (P < .05) in swine fed Ca benzoate, whereas N retention remained unaffected. Addition of all OA (formic and n-butyric acid, in particular) exerted a positive effect (P < .05) on the ID of amino acids (except for arginine, methionine, and cysteine). A similar effect (P < .05) was found for the TD of DM, OM, CP, Ca and total P and for the retention of N and Ca. In swine fed Ca benzoate, urinary pH decreased by 1.6 units (P < .001). In conclusion, dietary OA have a beneficial effect on the apparent ileal/total tract nutrient digestibilities, and Ca benzoate increased urine acidity, which could be effective against a rapid ammonia emission from manure of swine.     

Performance of laying hens as affected by split time and split composition dietary regiments using ground and unground cereals

A factorial experiment was conducted to study the effects on the performance of White Leghorn X Australorp laying hens of diets based on unground cereal grains, small morning and large afternoon meals, and morning and afternoon meals of different composition. From 10 to 21 weeks of age the pullets' food intake was restricted, using either a diet in which the wheat fraction (600 g/kg) was unground or a fully ground diet of similar composition. In the laying period the birds received either a diet (U) in which the limestone was granulated and most of the cereal fraction (wheat and oats or wheat and sorghum) was unground or a fully ground diet (G) of similar composition. Both laying diets were offered ad libitum (A), with 25% issued in the morning and 75% in the late afternoon (T) or as a protein concentrate (250 g/kg of total diet) in the morning and cereal/limestone fraction (750 g/kg) in the late afternoon (C). Rearing and laying performance were unaffected by rearing diet. Laying diet U resulted in a 5.2% increase in food intake and a 0.9 g increase in average egg weight compared with diet G. From 21 to 56 weeks of age, when the cereal/limestone fraction of the diet included oats (240 g/kg of total diet), diet U resulted in fewer (4.8/bird) eggs and a lower financial margin than diet G. From 56 to 80 weeks of age, when oats were replaced by sorghum, this trend was reversed (-3.5 eggs). Birds on diet C produced fewer (16.9) eggs of lower (1.5 g) average weight than birds on diet A, ate less (1.39 kg) food and had a lower financial margin.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of dietary carbohydrates and buffering capacity on nutrient digestibility and manure characteristics in finishing pigs

A 2 x 3 factorial experiment was conducted with 24 finishing pigs (Yorkshire x [Finnish Landrace x Dutch Landrace]) to determine the effects of dietary buffering capacity (BC) and carbohydrate sources on apparent total tract digestibility (TD), N retention, and manure characteristics. Twelve of these pigs were fitted with steered ileo-cecal value cannulas to measure the apparent ileal digestibility (ID) of N. Experimental variables were two levels of BC (High = 600 mEq/kg and Low = 530 mEq/kg) and three dietary carbohydrates (tapioca [28%], soybean hulls [25%], and sugar beet pulp [25%]). The two levels of BC were achieved by adjusting the amounts of alkalogenic limestone and acidogenic Ca sulfate in the diet. Pigs were fed twice daily at 2.4 x maintenance requirement for metabolizable energy (418 kJ ME/BW(0.75)). Chromic oxide was used as an indigestible marker. Feces and urine were collected over 5 d for nutrient balance and in vitro measurements of pH and ammonia emission over 7 d. No significant interactions between BC and dietary carbohydrates on the ID, TD, N retention, or manure characteristics were observed. Lowering BC with Ca sulfate did not affect digestibility of most nutrients, except for a negative impact on the TD of Ca (P = 0.015) and Mg (P = 0.003). Although all pigs receiving Ca sulfate had more acidic urine (by 0.49 pH units; P = 0.001), ammonia emission from manure was not lowered, irrespective of the carbohydrate source. Carbohydrates affected significantly the ID and TD of most nutrients, whereas N retention remained similar (P > 0.10). Urinary N:fecal N ratios in manure of pigs fed diets with tapioca, soybean hulls, and beet pulp were 2.09, 1.35, and 1.67, respectively. These ratios corresponded with in vitro ammonia emission (169, 125, and 148 mmol/7 d; P = 0.023). In conclusion, these results indicate that the acidification of urine in pigs fed Ca sulfate in the presence of NSP-rich carbohydrates was achieved. However, acidity of manure and ammonia emission were not affected. The addition of NSP from soybean hulls and(or) sugar beet pulp reduced ratios of urinary:fecal N, and thereby ammonia emission.     

Concentration of dietary calcium supplied by calcium carbonate does not affect the apparent total tract digestibility of calcium, but decreases digestibility of phosphorus by growing pigs

A regional experiment was conducted to test the hypothesis that the concentration of dietary Ca does not affect the digestibility of Ca or P in diets fed to growing pigs. Six diets based on corn, potato protein isolate, cornstarch, and soybean oil were formulated. All diets also contained monosodium phosphate, crystalline AA, salt, and a vitamin-micromineral premix. The only difference among the diets was that varying concentrations of calcium carbonate were used to create diets containing 0.33, 0.46, 0.51, 0.67, 0.92, and 1.04% Ca. All diets contained between 0.40 and 0.43% P. Six universities participated in the experiment and each university contributed 2 replicates to the experiment for a total of 12 replicates (initial BW: 23.1 ± 4.4 kg). Pigs were placed in metabolism cages that allowed total, but separate, collection of feces and urine from the pigs. Pigs within each replicate were randomly allotted to the 6 diets and fed experimental diets for 14 d with urine and feces being collected over a 5-d period. Diets, feces, and urine samples were analyzed for Ca and P, and the daily balance, the apparent total tract digestibility (ATTD), and the retention of Ca and P were calculated. Results indicated that intake, fecal excretion, and urinary excretion of Ca increased (linear, P<0.05) as dietary Ca concentration increased. The daily intake of P was not affected by the dietary concentration of Ca, but fecal excretion of P increased (linear, P<0.05) as dietary Ca concentrations increased. In contrast, urinary P output was decreased (linear, P<0.05) as dietary Ca increased. The retention of Ca increased (linear, P<0.05) from 1.73 to 4.60 g/d, whereas the retention of P decreased (linear, P<0.05) from 1.98 to 1.77 g/d as dietary Ca concentrations increased. However, if calculated as a percentage of intake, both Ca and P retention were decreased (linear, P<0.05) as dietary Ca concentration increased (from 55.4 to 46.1% and from 48.4 to 43.5%, respectively). The ATTD of Ca was not affected by the dietary concentration of Ca, but the ATTD of P was decreased (linear, P<0.05) from 56.9 to 46.2% as dietary Ca concentration increased. It is concluded that the dietary concentration of Ca does not affect the ATTD of Ca in calcium carbonate, but increased concentrations of dietary Ca may decrease the ATTD of P in diets based on corn, potato protein isolate, and monosodium phosphate.     

Apparent ileal and total-tract nutrient digestion by pigs as affected by dietary nondigestible oligosaccharides

The effects of two types of nondigestible oligosaccharides (NDO), fructooligosaccharides (FOS), and transgalactooligosaccharides (TOS) were studied on growing and weanling pigs' nutrient digestion. Dietary NDO were included at the expense of purified cellulose. Twenty-five 57-d-old growing pigs, averaging 15.9+/-.6 kg on d 0 of the experiment, were fed a corn-based control diet or the control with 6.8 or 13.5 g of FOS/kg or 4.0 or 8.0 g of TOS/kg (five pigs per diet). Feces were collected on d 28 to 32, and small-intestinal digesta were collected (slaughter technique) on d 42 to 47 of the experiment. Feeds, feces, and digesta were analyzed for DM, inorganic matter, CP, ether extract, and crude fiber. Dietary NDO did not significantly affect apparent fecal and small intestinal digestion of nutrients in growing pigs. After being fed a NDO-free diet through d 10 after weaning, 38-d-old weanling pigs (n = 20), averaging 10.4+/-.8 kg on d 0 of the experiment, were fed a control diet (based on cornstarch, casein, and oat husk meal) or the control with 10 or 40 g of FOS or TOS/kg (four pigs per diet). Feces and urine were collected on d 13 to 17, and ileal digesta were collected via a postvalve T-cecum cannula on d 33 to 37 of the experiment. Feeds, feces, and digesta were analyzed for DM, inorganic matter, CP, ether extract, starch, NDF, ADF, ADL, Ca, P, Mg, Fe, Cu, and Zn. Nonstarch neutral-detergent soluble carbohydrates (NNSC) completed the mass balance for the carbohydrates. Urine was analyzed for N and minerals. The apparent fecal digestion of NNSC increased in the NDO-supplemented diets. The TOS-fed pigs tended (P<.10) to have a higher apparent fecal digestion of CP than the FOS-fed and control pigs but excreted more N via the urine (P<.01). Nitrogen and mineral balances were not affected. The FOS was nearly completely degraded prececally. Mean fiber digestion was lower at the fecal compared with the ileal level, as was the extent of NDO effects. This indicates that fiber digestion requires more than 2 wk to adapt to dietary NDO. Apparent ileal digestion of hemicellulose increased for the NDO-supplemented diets (P<.05), but that of NNSC decreased (P<.001). Thus, under the well-controlled conditions of this experiment, dietary NDO hardly affected nutrient digestion in well-kept growing and weanling pigs. However, digestion of dietary nonstarch carbohydrates may be affected.     

Effect of fumaric acid and dietary buffering capacity on ileal and fecal amino acid digestibilities in early-weaned pigs

Experiments were conducted to determine the effect of fumaric acid supplementation and buffering capacity of the diet on ileal and fecal digestibilities of CP, GE, and amino acids in early-weaned pigs. In two experiments, 12 pigs each were weaned at 14 d of age and fitted with a simple T-cannula at the distal ileum between 15 and 17 d of age. In both experiments, the pigs were fed four diets, based on wheat and soybean meal without (control) or with 1, 2, or 3% fumaric acid according to a balanced two-period change-over design. In Exp. 2, the buffering capacity of the diets was increased by supplementation of 3% sodium bicarbonate. The pigs were fed three times daily: equal amounts at 8-h intervals. The diets were supplied at a rate of 5% (wt/wt) of body weight. The inclusion of fumaric acid to the diet with a low buffering capacity increased (P < .05) the ileal digestibilities of CP, GE, and the majority of amino acids. The highest responses were found at an inclusion level of 2% fumaric acid. The improvements in apparent ileal amino acid digestibilities ranged from 4.9 to 12.8 percentage units. Supplementation of fumaric acid to a diet with a high buffering capacity led only to numerical increases in ileal digestibilities of CP, GE, and amino acids. In both studies, fumaric acid supplementation had no effect (P > .05) on the fecal digestibilities of CP, GE, and amino acids, except histidine. A high buffering capacity of the diet decreased the ileal amino acid digestibilities by 1 to 10 percentage units compared with diets with the low buffering capacities. In both experiments, ileal and fecal digestibilities were higher (P < .05) in Period 2 (on d 24 after weaning) than in Period 1 (on d 11 after weaning). A positive correlation (P < .05) between ileal digestibilities and fumaric acid supplementation to the diets with the low buffering capacities was observed in Period 1 (on d 11 after weaning), but not in Period 2 (on d 24 after weaning). No relationship (P > .05) between ileal digestibilities and fumaric acid supplementation to the diets with a high buffering capacity could be established. In conclusion, supplementation of fumaric acid to starter diets during the first 3 to 4 wk after weaning increases the ileal digestibilities of GE, CP, and amino acids.     

Role of dietary calcium and available phosphorus in the aetiology of tibial dyschondroplasia in growing turkeys

1. Large White male turkeys from a heavy commercial male-line were fed 16 diets containing 4 concentrations of calcium (6, 10, 14 and 18 g/kg) and available phosphorus (3, 5, 7 and 9 g/kg) in a 4 x 4 factorial experiment. There were three replicates (pens) of each treatment and the skeletal health, morphology and mineral status of 4 turkeys from each pen were assessed at 7, 10 and 13 weeks of age. 2. The prevalence of tibial dyschondroplasia increased after 7 weeks of age and was present in 50 and 71% of turkeys respectively at 10 and 13 weeks. The lesion was localised in the caudal aspect of the proximal tibiae. Dietary calcium and available phosphorus did not affect the prevalence of the lesion except in turkeys on the diet containing 6 g calcium/kg, where body weight and the incidence of tibial dyschondroplasia were low. 3. Histological investigation showed no evidence of rachitic changes. 4. Low dietary calcium was associated with lower tibial plateau angles at 10 and 13 weeks of age. Tibial torsion and the angle of rotation were not affected by dietary treatments or age. Tibial torsion and the angle of rotation were not affected by dietary treatments or age. 5. Increasing dietary calcium increased tibial radiodensity, cortical density and the widths of the cortex and proximal tibiotarsus. Radiodensities increased to 10 weeks and were significantly lower at 13 weeks of age. 6. Bone ash, calcium and phosphorus declined with age, particularly between 10 and 13 weeks, whereas bone calcium: phosphorus ratios were not affected by dietary treatment or age. 7. Dietary calcium was positively associated with blood calcium and calcium ion concentrations and was without effect on blood phosphorus. Available phosphorus was associated positively with increased blood phosphorus and lower calcium ion concentrations but had no effect on total calcium. Alkaline phosphatase activity was low at high concentrations of dietary calcium with low available phosphorus and there was higher activity on diets containing low calcium and high available phosphorus.     

Influence of dietary manganese on performance, lipid metabolism, and carcass composition of growing and finishing steers

A study was conducted to determine the effect of dietary Mn on performance of growing and finishing steers, and to evaluate the effect of pharmacological concentrations of Mn on lipid metabolism and subsequent carcass quality in steers. One hundred twenty Angus cross steers were blocked by BW and origin and assigned randomly to one of six treatments (four replicate pens per treatment) providing 0 (control), 10, 20, 30, 120, or 240 mg of supplemental Mn/kg of DM from MnSO4. Steers were fed a corn silage-based growing diet for 84 d, and then switched to a corn-based finishing diet for an average of 112 d. The control growing diet analyzed 29 mg of Mn/kg of DM, whereas the control finishing diet analyzed 8 mg of Mn/kg of DM. Jugular blood samples were obtained on d 56 of the growing and finishing phase for plasma Mn and glucose analysis. Final BW, DMI, ADG, and G:F did not differ (P = 0.38 to P = 0.98) across treatments during growing and finishing phases. Plasma Mn concentrations were not affected by treatment; however, liver and LM Mn at slaughter increased linearly (P = 0.02 and 0.002, respectively) with increasing dietary Mn. Plasma glucose concentrations did not differ (P = 0.90) among treatments. Serum nonesterified fatty acid concentrations tended (P = 0.10) to decrease linearly with increasing dietary Mn on d 56 of the finishing phase. Longissimus muscle lipid concentration was affected quadratically (P = 0.08) by dietary Mn. Muscle lipid seemed to increase slightly when steers were fed 30 or 120 mg of Mn/kg of DM, but decreased with the addition of 240 mg of Mn/kg of DM. Carcass characteristics were not affected by dietary Mn. Manganese concentrations of 29 and 8 mg/kg of DM in the growing and finishing diets, respectively, were adequate for maximizing performance of growing and finishing steers in this experiment. Supplementing physiological or pharmacological concentrations of Mn affected lipid metabolism; however, this did not result in altered carcass characteristics.