牦牛与黑白花牛的氮平衡比较研究

接近初情期的牦牛和黑白花公牛各3头，于代谢厩中进行精料型（精粗比为4：1）和粗料型（精粗比为1：4）日粮条件下的氮平均对比试验。结果表明，不论牦牛还是黑白花牛，干物质采食量（DMI）、粪氮（FN）、尿氮（UN）和干物质消化率（DMD）均随精料含量上升而升高（P＜0．01），而进食氮（NI）的利用效率则随NI的升高而下降（P＜0．01）。在粗料型的日粮条件下，牦牛对NI的利用效率（58．2％）高于（P＜0．05）黑白花牛（49．0％），二者的DMD（45％）无差异；而在精料型的日粮条件下，NI的利用效率（22％）和DMD（64％）均不随牛种而变化（P＞0．05）。从这些结果得出结论：牦牛与黑白花牛消化道的吸收效率是一样的，在精料型日粮条件下，牦牛机体组织存留氮的能力低于黑白花牛；在粗料型日粮条件下，牦牛比黑白花牛更能有效地利用蛋白资源。     

The influence of dietary fiber digestibility on the nitrogen requirements of mature horses

Mature geldings at maintenance were fed different diets in a 4 x 4 Latin square design balanced to account for residual effects in an attempt to determine whether differences in the digestibility of the fibrous portions of feedstuffs would influence dietary nitrogen (N) requirements. Diet 1 contained corn and soybean meal (SBM); diet 2, corn, corn oil and urea; diet 3, corn, SBM, straw and urea; diet 4, corn, alfalfa and urea. Urea supplied 50% of the total N in diets 2 and 3 and 39% of the total N in diet 4. The diets were fed in amounts that met National Research Council (NRC) recommendations for daily digestible energy intakes by mature horses at maintenance and met or exceeded total daily N requirements. True absorbed N was calculated by subtracting the fecal N associated with neutral detergent fiber (NDF-N) from total N intakes; true digestibilities of N ranged from 92.4 to 95.9%. Endogenous and metabolic fecal N excretions ranged from .37 to .56 g N/100 g dry matter intake. Although none of the diets as fed were deficient in N, apparent N digestibility was only 64% of N intake when the horses were fed the diet containing straw (diet 3), compared with 72.5 to 79.6% of total N intake among diets 1, 2 and 4 (P less than .01). Fecal excretions of water soluble, bacterial cell-associated and intestinal cell-associated N fractions were greatest when diet 3 was fed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Growth of yearling fillies fed alfalfa or soybean meal

Sixteen Quarter Horse yearling fillies were used in a 112-day randomized block experiment to determine the comparative efficacy of alfalfa hay protein to support growth in young horses. The yearlings were divided into two groups of eight and paired according to weight and age, with one yearling from each pair randomly allotted to each diet. Group 1 was fed a diet of coastal Bermuda grass hay and concentrate. The corn-based concentrate was supplemented with soybean meal such that the total diet for group 1 contained approximately 13% CP. Group 2 was fed a diet that also contained approximately 13% CP and consisted of alfalfa hay and a similar concentrate without soybean meal. Yearlings were fed the diets in a 60:40 grain-to-hay ratio, and intakes between members of each pair were equalized. The calculated digestible energy density in both final diets was approximately 2.85 mcal/kg, and the protein:calorie ratio for both diets was approximately 45 gm/Mcal. Body weight, body length, heart girth, wither and hip heights, as well as forearm, gaskin and cannon bone circumferences were measured every 28 days. Rump fat thickness was measured ultrasonically every 28 days. Physical measures of growth were similar for horses eating each diet (P>0.05). Also, blood urea nitrogen was similar for horses eating each diet (P>0.05) and was not reflective of differences in nitrogen metabolism. The fillies fed the SBM-supplemented diet retained more nitrogen more efficiently than did fillies fed the alfalfa diet (P<0.05), and the SBM-fed fillies had higher concentrations of osteocalcin on days 14, 28, 42, and 112. It can be concluded that SBM and alfalfa proteins were equally effective in providing growth to young horses; however, the biological value of absorbed nitrogen appeared to be higher in the fillies fed the SBM-supplemented diet. also, differences in serum osteocalcin concentrations indicate that the SBM-fed fillies were experiencing a greater amount of osteoblastic activity than the alfalfa fed fillies.     

日粮类型对奶牛粪尿特性及氮排放的影响

通过研究不同类型日粮对泌乳奶牛粪尿及氮排放的影响,达到减少和控制氮排放的目的,本试验选用12头体重514 kg、年龄3～5岁的中国荷斯坦奶牛为试验动物,分为3组,分别饲喂粗料为干秸秆玉米,精粗比40∶60的A日粮、粗料为玉米青贮,精粗比分别是40∶60和60∶40的B和C日粮进行了对其粪尿特性及氮排放的试验研究。结果表明,日粮类型对奶牛粪便及尿液产生量均有一定的影响。粪便产生量结果为秸秆型A日粮>青贮型低精比B日粮>青贮型高精比C日粮。3种日粮的尿液产生量为C日粮>B日粮>A日粮。同时,日粮类型对奶牛氮平衡具有显著的影响,秸秆型日粮的乳氮、尿氮含量和氮的消化率极显著低于青贮型日粮低(P<0.01),粗料均为青贮玉米条件下,随日粮精料水平的提高,氮消化率和尿氮极显著增加(P<0.01),粪氮和乳氮增加不显著(P>0.05)。结果提示,秸秆型日粮的摄入氮主要是从粪中排出,粗料为青贮玉米时,随日粮精料水平的提高粪氮比例减少,而尿氮比例增加,粪氮和尿氮占总粪尿氮的比例基本一致。     

Nitrogen Retention and Plasma Amino Acid Responses in Mature Geldings Fed Three Dietary Concentrations of Lysine

Six mature Quarter Horse geldings (age, 11.5 ± 4.7 years; body weight [BW], 526 ± 9.2 kg) were used in a replicated 3 × 3 Latin square design to determine the effects of three dietary lysine (Lys) levels on nitrogen (N) retention and plasma amino acid (AA) concentrations. The geldings were fed a basal diet of concentrate and Bermuda grass hay supplemented with synthetic essential amino acids (EAA) to meet estimated requirements for EAA. Geldings were fed one of three dietary treatments: (1) a basal diet deficient in Lys (L−; 0.027 g of Lys•kg⁻¹ BW•d⁻¹); (2) a basal diet supplemented with synthetic Lys to meet National Research Council (NRC; 2007) requirements (L+; 0.036 g of Lys•kg⁻¹ BW•d⁻¹); or (3) a basal diet supplemented at twice the recommended Lys requirement (2 × L; 0.070 g Lys•kg⁻¹ BW•d⁻¹). Horses fed the 2 × L diet had higher N intakes (P = .0056) than horses fed either the L− or L+ diet. However N retention (P = .63) was not different between treatments. Plasma Lys was greater (P < .0001) in 2 × L than L− and L+ diets. Plasma threonine (Thr; P < .01), methionine (Met; P = .03), and total plasma non-EAA (P < .05) concentrations decreased as dietary Lys increased. These results suggest N retention is not a good response criterion for evaluating the AA requirements of mature horses. However, plasma AA data indicated more efficient use of Thr and Met when horses were fed dietary Lys in concentrations greater than the current requirement recommended by the Nutrient Requirements of Horses (National Research Council, 2007).     

Effect of deficiencies of single essential amino acids on nitrogen and energy utilisation in chicks.

1. Diets 50% deficient in single essential amino acids were fed to chicks from day 8 to day 18 after hatching to evaluate body-weight gain, food consumption, body composition, nitrogen (N) and energy utilisation. 2. Body-weight gain was reduced most severely by deficiency of isoleucine followed in decreasing order by threonine, arginine, valine, histidine, tryptophan, methionine plus cystine, phenylalanine plus tyrosine, leucine and lysine, and possible reasons for the differences are discussed. 3. Body-weight gain and food efficiency were highly correlated with food consumption but metabolisable energy value of diets was not affected by single essential amino acid deficiencies. 4. Generally N retention (N retained/N consumed) and energy retention (energy retained/energy consumed) reflected food consumption, except for a lower N retention by chicks fed on the methionine plus cystine-deficient diet and for a lower energy retention by chicks fed on the valine deficient diet. 5. The amino acid deficient in the diet was present at very low concentration in the blood plasma.     

Nitrogen Retention and Nutrient Digestibility in Geldings Fed Grass Hay,Alfalfa Hay,or Alfalfa Cubes

This study was conducted to determine whether feeding different physical forms of hay alters nutrient digestibility and nitrogen retention (NR). Six Quarter Horse geldings were assigned to any one of three different dietary treatments in three 14-day periods. The diets included long-stem Bermuda grass hay (G), long-stem alfalfa hay (A), and alfalfa cubes (C). In the final 4 days of each period, horses were fitted with harnesses for total collection of urine and feces. Samples of feed, orts, feces, and urine were analyzed for dry matter, organic matter, acid detergent fiber, neutral detergent fiber, and nitrogen (N). Digestibility of dry matter, organic matter, and N was greatest for A, intermediate for C, and smallest for G (P < .05). Digestibility of acid detergent fiber was greater (P < .05) for A than G or C, and neutral detergent fiber digestibility was greater (P < .05) for A or G than C. Nitrogen intake (NI) was greatest for A, intermediate for C, and smallest for G (P < .05). Fecal N excretion was not different between diets, but urine N excretion was greater (P < .05) for A and C as compared with G. When expressed as a percentage of NI, NR did not differ among diets. We concluded that NR in mature horses increases with NI, but N utilization is not significantly influenced by the physical form or crude protein content of the hay fed. Potential differences in fiber digestibility and daily fecal output are factors to consider when incorporating processed forages into feeding programs of horses.     

Effects of adding fiber sources to reduced-crude protein,amino acid-supplemented diets on nitrogen excretion,growth performance,and carcass traits of finishing pigs

Two experiments were conducted to evaluate the effects of adding fiber sources to reduced-crude protein (CP), amino acid-supplemented diets on N excretion, growth performance, and carcass traits of growing-finishing pigs. In Exp. 1, six sets of four littermate barrows (initial weight = 36.3 kg) were allotted randomly to four dietary treatments to determine N balance and slurry composition. Dietary treatments were: 1) fortified corn-soybean meal, control, 2) as fortified corn-soybean meal with CP lowered by 4 percentage units and supplemented with lysine, threonine, methionine, tryptophan, isoleucine, and valine (LPAA), 3) same as Diet 2 plus 10% soybean hulls, and 4) same as Diet 2 with 10% dried beet pulp. Nitrogen intake, absorption, and retention (g/d) were reduced (P < 0.04) in pigs fed the low- protein diets, but they were not affected (P > 0.10) by addition of fiber sources to the LPAA diet. However, N absorption, as a percentage of intake, was not affected (P > 0.10) by dietary treatment. Nitrogen retention, expressed as a percentage of N intake, was increased (P < 0.02) in pigs fed the low-protein diets, but it was not affected by fiber addition to the LPAA diet. Urinary and total N excretion was reduced (P < 0.01) by 50 and 40%, respectively, in pigs fed the low- protein diets, but it was not affected (P > 0.10) by fiber addition. However, fiber addition to the LPAA diet tended to result in a greater proportion of N excreted in the feces than in the urine. Slurry pH, ammonium N content, and urinary urea N excretion were reduced (P < 0.10) in pigs fed LPAA, and a further reduction (P < 0.06) in slurry ammonium N content and urinary urea N was observed with fiber addition. Also, fiber addition to the LPAA diet increased (P < 0.02) slurry VFA concentrations. In Exp. 2, 72 pigs were blocked by body weight and sex and allotted randomly to three dietary treatments that were similar to those in Exp. 1, with a corn-soybean meal control diet, LPAA diet, and a LPAA diet with 10% soybean hulls. Pigs were fed the diets from 28.6 to 115 kg, and all pigs were killed for collection of carcass data. Growth performance and most carcass traits were not affected (P > 0.10) by dietary treatment. These data suggest that reducing CP with amino acid supplementation markedly decreased N excretion without influencing growth performance. Fiber addition to a LPAA diet had little effect on overall N balance or growth performance, but tended to further reduce slurry ammonium N concentration and increase volatile fatty acid concentrations.     

Effects of grass forage species and long‐term period of low quality forage diet feeding on growth performance,nutrient utilization and microbial nitrogen yield in growing wether lambs

Six growing lambs were used to evaluate the feeding value of two forage‐based diets in a long‐term feeding period by measuring body weight (BW) gain, digestibility, nitrogen (N) retention and microbial N (MBN) yield. The animals were fed imported low‐quality timothy hay (TH) with concentrate diet (THD) or imported low‐quality Italian ryegrass straw (IR) with concentrate diet (IRD) for 9 months. The forages were offered at 2% BW, and concentrate was fed at 40% of forage intake. The BW gain averaged 82.6 and 66.2 g/day for THD and IRD, respectively, without showing significant difference. Average forage intake (% BW) was significantly greater for IR than for TH, although it was not affected by feeding periods. The digestibility did not differ between diets or periods. The numerically greater (P = 0.06) ratio of retained N to absorbed N for IRD than that for THD was prominent. Neither diet nor period had significant effect on MBN supply and efficiency of MBN synthesis. The results suggest that the IR‐based diet can be also used for long‐term periods of feeding to growing ruminant animals as a grass hay‐based diet without any detrimental effects on nutrient utilization and growth performance.     

Food intake adjustments of chicks: Short term reactions to deficiencies in lysine,methionine and tryptophan

1. Two experiments were conducted to compare food intake responses of broiler chicks fed diets varying in lysine, methionine, and tryptophan. Diet D was formulated to create simultaneous deficiencies of lysine, methionine, and tryptophan. Diet A matched National Research Council (1984) recommendations for broilers, and diets B and C were, respectively, 2:1 and 1:2 mixes of diets A and D.

2. Short‐term food intake can provide information on the sequences of adaptation of chicks to a diet deficient in essential amino acids.

3. Chicks consumed 26% less of diet D than A during the first 24 h posthatch. When chicks fed diet A or D to 7 d of age were then fed one of 4 diets singly, within 24 h intake was lowest for chicks fed diet D. Within 48 h, food intake of diet C was more than that of diet D and less than that of diet A, while for diet B intake was more than of diet D but not different from diet A.

4. In the second experiment, chicks were fed diet A to 8 d and then diets A or D alone or given a choice of diets A and D from 8 to 20 d of age. Within 4 to 8 h, food intake of chicks fed diet D alone decreased markedly followed by partial recovery within 24 h. In a choice setting, consistent preference of Diet A over Diet D was observed within 7 h followed by stabilisation at about 65% diet A to 35% diet D.

5. Chicks fed diet D alone from 8 to 20 d of age, then placed in the same choice situation preferred diet A to D with a delay of less than one h and stabilisation at about 85%. Chicks provided a choice of diets A and D from 8 to 20 d, and then diet D alone reduced their food intake more quickly than those not given a choice initially.

6. Broiler chicks appear to react to amino acid deficiencies within a short period (hours) by adjusting their feed intake and/or selection. The response is influenced by age and prior experience.     

Genetic-diet interactions in the Hyperkalemic Periodic Paralysis syndrome in Quarter Horses fed varying amounts of potassium: I. Potassium and sodium balance, packed cell volume and plasma potassium and sodium concentrations

Six broodmares that were genetically tested to be heterozygous (H/N) and six broodmares that were tested to be homozygous negative (N/N) for Equine Hyperkalemic Periodic Paralysis (HYPP), that were descendents of the same stallion, were used in a replicated 3×3 Latin square experiment to determine the genetic-diet relationships in the HYPP syndrome.¹ The mares were fed rations consisting of 65% pelleted concentrate and 35% Coastal Bermuda grass hay that provided 1.1 (diet A), 1.9 (diet B) and 2.9% (diet C) potassium. The experimental periods were 14 days long, resulting in 28 meals per period. At meals 1 and 27, blood samples were taken every 30 minutes for 12 hours and every 10 minutes from 2 to 5 hours post-feeding. Total urine and fecal collections were made on the last 4 days of each period.Water, feed and fecal samples were analyzed for sodium and potassium content. Blood was analyzed for packed cell volume (PCV) and plasma potassium (K⁺) and sodium (Na⁺) concentrations.Apparent absorption of potassium was 99.8% across all diets, and potassium was excreted principally in the urine. More potassium was retained when the horses were fed diet B than diets A or C. Apparent absorption of sodium was 99.6% with no difference by diet. Neither potassium nor sodium balances were affected by HYPP status.There was no post-prandial pattern of plasma K⁺ concentration seen when the horses were fed the low potassium diet. When fed the higher potassium diets, they had greater plasma K⁺ values and exhibited a post-prandial peak at 2 to 5 hours after feeding. This peak occurred in all of the horses, meaning that plasma K⁺ cannot be used as a diagnostic aid for the presence of the HYPP mutation. By meal 27, some adaptation had occurred resulting in lower plasma K⁺ values when the horses were fed the higher potassium diets. The horses had increased plasma K⁺ concentrations throughout the post-prandial period while fed diet B compared to diet A, agreeing with the positive potassium balance seen in this experiment. The HYPP H/N horses had lower plasma Na⁺ concentrations in the early post-prandial hours and continuously greater PCV values than the HYPP N/N horses.     

Dietary factors affecting the utilisation of protein by laying hens and their effects on the concentrations of certain nitrogenous constituents in the excreta

New techniques involving extraction with organic solvents and lithium carbonate solution have been used to fractionate nitrogenous components of the excreta from laying hens fed diets in which the supplementary protein was groundnut meal, poor‐quality fish meal or good‐quality fish meal. The effect of adding methionine or lysine or both to the groundnut diet was also studied.

The proportion of ingested nitrogen excreted as uric acid or urate was significantly higher when the dietary protein supplement was groundnut meal than when it was good‐quality fish meal or groundnut meal supplemented with both lysine and methionine. Nitrogen retention, egg production and the apparent digestibility of nitrogen were higher on diets containing good‐quality fish meal than on diets containing groundnut meal alone. Intermediate effects were obtained when feeding diets supplemented with poor‐quality fish meal of groundnut meal containing either lysine or methionine. The implications of these findings are discussed. The main differences in protein utilisation associated with variations in dietary protein quality were reflected in the proportions of ingested nitrogen excreted as urates and as protein. Other nitrogenous components of excreta examined showed little variation with dietary protein quality. Benefits derived from the addition of methionine and lysine to the groundnut diet were obtained mainly by a more efficient use of absorbed amino acids.     

Effect of dietary cation-anion balance in mineral balance in anaerobically exercised and sedentary horses

Eight geldings and four mares were randomly assigned treatments within three 4x4 Latin square design experiments to study the effects of dietary cation-anion balance (DCAB) on mineral balance and dry matter digestibility in sedentary and anaerobically exercised horses. Four diets with an average DCAB (calculated as meq ((Na+K+) - Cl-)/kg of diet dry matter) of +24 (Low, L), +127 (Medium Low, ML), +227 (Medium High, MH) and +352 (High, H) were fed for a 21 day adjustment period followed by a 72 hour collection period. Diets consisted of a pelleted base concentrate of com, soybean meal and cottonseed hulls fed with either native prairie grass or bermuda grass hay in a 60:40 ratio. Diet L was formed by adding calcium chloride and ammonium chloride to the base concentrate, diet ML was formed by adding calcium chloride, and diet H was formed by adding potassium citrate and sodium bicarbonate. Diet MI-I received no supplementation and served as the control. Representative samples of feed, feces and urine were analyzed for mineral content and mineral balances were calculated by difference. Fecal output was greater (p <.05), and thus, dry matter digestibility was lower in exercised homes consuming diet L versus diet H. Sodium balance was greater (p <.05) in sedentary horses consuming diet MH as compared to those consuming diets ML and L Sodium balance was greater (p <.05) in exercised homes consuming diet H as compared to those consuming diets ML and L Potassium balance was greater (p <.05) in sedentary horses consuming diet H as compared to those horses consuming diet ML, however, potassium balance was not affected by DCAB in exercised horses. No significant differences were detected in chloride or magnesium balances in the sedentary horses, although chloride balance was greater (p <.05) and magnesium balance was lower (p <.05) in exercised homes consuming diet L as compared to all other diets. In sedentary homes, phosphorus balance was reflective of intake with differences (p <.05) observed between all treatments. However, in exercised homes, phosphorus balance was lower (p <.05) oniy for those consuming diet L. Calcium balance decreased significantly as DCAB decreased between all treatments in sedentary horses, while calcium balance in exercised homes was greater (p <.05) for homes consuming diet H as compared to those consum- ing diet L.Previous research from our laboratory has shown that both exercised and sedentary horses consuming diets with a low DCAB experience a nutritionally induced metabolic acidosis. The current data indicate that anaerobically exercised and sedentary horses consuming these diets excrete significantly more calcium in the urine resulting in decreased calcium balances. Prolonged consumption of diets with a low DCAB may lead to a significant demineralization of bone and a subsequent weakening of the skeleton.     

The effect of the combination of microbial phytase and amino acid supplementation of diets for finishing pigs on P and N excretion and carcass quality.

The objective of this study was to evaluate the effect of a combined low-protein, low-phosphorus diet supplemented with limiting amino acids and microbial phytase on performance, nutrient utilization and carcass characteristics of late-finishing barrows. 4 x 8 crossbreed barrows were continuously housed in metabolism cages from 70-110 kg BW and were fed diets, either conventional (A) or protein reduced (B) or protein and phosphorus reduced diets (C) based on barley, maize and soybean meal. Diet A (positive control) contained in air dry matter 13% and 10% CP as well as 0.49% and 0.42% P at growth phases I (70-100 kg BW) or 11 (100-110 kg BW), respectively. Diet B was low in CP (11.3%, 8.4%), diet C low in CP and low in P (CP: as B, P: 0.36%, 0.30%). To diet B the limiting amino acids lysine, methionine, threonine and trypthophan were added to meet the levels in diet A. To diet C the limiting amino acids and 800 FTU/kg Aspergillus-phytase were supplemented. At the end of the balance periods the barrows were slaughtered, the carcasses scored and loin chops, ham and Phalanx prima IV were analysed for nutrients and minerals. The CP or P reduction in diets B and C did not generally negatively affect growth, feed efficiency, absolute nitrogen retention or overall carcass performances of the pigs. With the low CP diets B and C, N excretion per unit BWG was decreased by about 23%. The addition of microbial phytase (diet C) increased apparent total tract digestibility of P by about 20%. In spite of 30% reduction of P intake (diet C), the absolute P retention related to 1 kg BW did not differ between treatments. Thus, phytase supplementation in diet C reduced P excretion per unit BWG by about 33%. Phytase raised apparent digestibility of Zn by about 20% but not Ca digestibility. Generally the carcass traits and meat characteristics were not affected by any of the diet strategies. Mineralization of the Phalanx prima IV was also similar in all treatment groups. However, phytase supplementation led to significantly increased zinc concentration in bones (25%). In contrast, Fe incorporation into the Phalanx prima IV was not affected. In general, the feeding regimen introduced in this experiment offers substantial benefits in maintaining a sustainable environmental-friendly pork production even at the stage of late-finishing barrows.     

Concepts in Protein Digestion and Amino Acid Requirements of Young Horses

There are numerous industry situations in which horses are N sufficient, but amino acid deficient. Although simple formulation of diets and consideration of nutrient-to-calorie ratios against requirements may appear to produce feeding programs that are suitable for horses, other factors, such as diet, rate of intake, site of nutrient absorption, horse age, and growth rate, must be considered when determining whether or not requirements are actually met. As an example, some yearlings kept in confinement consume concentrate and hay that fail to satisfy amino acid requirements. Other yearlings grazing very high quality pastures with no supplemental feed are able to meet their lysine requirement and achieve moderate growth. Field studies have documented that trends to manage weanlings and yearlings in a similar nutritional fashion are contributing to problems associated with rapid growth. Weanlings cannot process roughage at levels used effectively in yearlings, yet farms typically provide concentrate-to-hay ratios for weanlings inconsistent with NRC requirements and recommendations. Research on protein intake, site of absorption, concentrate type and intake, and grazing behavior must all be combined to be precise regarding adequate supply of protein quality to horses.     

Nutrients intake,digestibility, nitrogen balance and growth performance of sheep fed different silages with or without concentrate

The experiment was conducted to investigate the influence of maize (Zea mays), sorghum (Sorghum bicolor) and millet (Pennisetum americannum) silages with or without concentrate on nutrients intake, digestibility, nitrogen balance and weight gain in Sipli sheep. Six experimental diets were formulated having 100% maize silage (MS), maize silage and concentrate as 50:50 (MSC), 100% sorghum silage (SS), sorghum silage and concentrate as 50:50 (SSC), 100% millet silage (MiS) and millet silage and concentrate as 50:50 (MiSC), respectively. For this purpose, 24 Sipli lambs were randomly allotted to six experimental diets in a completely randomized design for 90 days, four lambs per diet. The results indicated that among various silage diets, lambs fed MS diet consumed higher dry matter (DM) than those fed SS and MiS diets. Likewise, lambs offered MSC had higher dry matter intake than those fed SSC and MiSC diets. Crude protein (CP) and neutral detergent fibre (NDF) consumed by the lambs also followed the similar trend. Higher DM, CP and NDF digestibilities were also observed in lambs fed MS and MSC diets than those fed SS, SSC, MiS and MiSC diets. Overall digestibilities of DM, CP and NDF were higher in experimental diets containing silage with concentrate. Lambs fed MS diet had 2.79 g/day and 4.45 g/day higher N retention than those fed SS and MiS, respectively. Similarly, lambs fed MSC diet had 2.24 g/day and 5.12 g/day higher N retention than those fed SSC and MiSC diets, respectively. The results showed that lambs fed MSC gained more daily weight gain had better feed conversion ratio than those fed MS, SS, SSC, MiS and MiSC diets. The findings of the present study indicated that lambs fed MSC diet had higher nutrients intake, digestibility, nitrogen balance and weight gain.     

Influence of urea molasses treated wheat straw fermented with cattle manure on chemical composition and feeding value for growing buffalo calves

The study was conducted to examine the chemical composition of urea–molasses treated wheat straw (WS) fermented with cattle manure (CM) and its feeding value for growing buffalo male calves. Wheat straw treated with varying levels of urea (0%, 2% and 4%) and molasses (2% and 4%) was ensiled with 30% cattle manure (on dry matter basis) for different fermentation periods (20, 30 and 40 days). Fermented wheat straw (FWS) after each fermentation period was analyzed for pH, dry matter (DM), crude protein (CP), true protein (TP), ammonia nitrogen (NH₃-N), acid detergent fiber (ADF) and neutral detergent fiber (NDF). Maximum pH, DM, CP, TP and NH₃-N and minimum NDF contents were observed with 4% urea. The 4% molasses level increased the CP, TP and NH₃-N contents of FWS, but pH, DM and NDF remained unchanged after 40 days of fermentation. The 4% urea × 4% molasses interaction resulted in maximum DM, CP, TP, NH₃-N after 40 days of fermentation period and this combination was used for large scale production of FWS to evaluate its feeding value for calves. Four isonitrogen and isocaloric diets were formulated. The control FWS 0 diet contained no FWS while in FWS 15, FWS 25 and FWS 35 diets concentrate was replaced with 15%, 25% and 35% FWS, respectively. The diets were randomly allotted to four groups of 28 calves 9–12 months of age, seven in each group, in a randomized complete block design to examine the nutrient intake, digestibility, nitrogen balance and weight gain. An increased DM, organic matter (OM), CP and NDF intakes were observed in calves fed FWS diets compared to those fed FWS 0 diet. Nitrogen retention increased significantly with increasing the level of FWS. The DM, OM, CP and NDF apparent digestibilities were non-significant in calves fed different levels of FWS. A linear increase in weight gain was noticed in calves fed diets containing increasing level of FWS.     

Taurine status in normal dogs fed a commercial diet associated with taurine deficiency and dilated cardiomyopathy

Taurine (Tau) deficiencies have been associated with the feeding of commercial lamb-meal and rice diets to dogs. We hypothesized that the poor digestibility of some lamb-meals may limit sulphur amino acids availability for Tau synthesis and/or increase of Tau degradation in the gut. Growing dogs were fed either a lamb-meal-based (Diet A) or poultry by-product-based (Diet B) commercial diet. Plasma, whole blood and urinary Tau were measured for 22 weeks. Plasma and whole blood Tau concentrations were similar between the groups throughout the study. Urinary excretion of Tau in dogs fed diet A was 3.2 times greater than that from dogs fed Diet B, suggesting greater renal reabsorption and the need for conservation of Tau in the Diet A group. Food restriction affected Tau status as indicted by a positive correlation of food intake and urinary Tau. Dogs fed Diet A were given antibiotics to inhibit bacterial activity in the gut. Increases in breath hydrogen, indicative of increased bacterial activity, correlated negatively with urinary Tau. Urinary Tau increased by 54% when methionine (Met) was supplemented to Diet A, supporting the suggestion of a low bioavailability of sulphur amino acids and/or an increased fecal loss of Tau in dogs consuming Diet A.     

Use of additives to capture nitrogen in ammoniated wheat straw: Intake, ruminal parameters, digestibility and nitrogen utilization in buffaloes

This study examined the influence of urea treated wheat straw (UTWS) ensiled with additives on feed intake, digestibility, ruminal characteristics and N utilization in Nili-Ravi buffalo bulls (Babulus bubalis) fed ad libitum. Wheat straw was treated on large scale with 4% urea at a 50% moisture level. The UTWS was ensiled with 6% CSL, 6% acidified molasses, 2% acetic acid and 2% formic acid on DM basis in four different cemented trench silos for 15 days. Four diets each having 50% dry matter (DM) from UTWS ensiled with acetic acid (AD), formic acid (FD), acidified molasses (MD) or corn steep liquor (CD) and 50% DM from concentrate mixture were fed to ruminally cannulated bulls in a 4 × 4 Latin square design. Ruminal total VFA, acetate, cellulolytic ruminal bacterial count, DM and NDF degradability were significantly higher with MD and CD diets compared with AD and FD diets. Intake of different feed fractions was higher in bulls fed MD and CD diets. Total tract apparent digestibility of nutrients was similar across all treatments. Nitrogen retention was higher in bulls fed MD and CD diets than those fed AD and FD diets. Ensiling UTWS with fermentable carbohydrates sources having low pH compared to organic acids increased the N fixation in the matrix of cell wall fiber thus slowing its release at ruminal level that probably enhanced the N synchronization with carbon skeleton (fiber fermentation) and this consequently improved the N utilization.     

Copper and zinc balance in exercising horses fed 2 forms of mineral supplements

Studies comparing the absorption and retention of various forms of trace minerals in horses have yielded mixed results. The objective of this study was to compare Cu and Zn absorption and retention in exercising horses where the mineral was supplemented in the sulfate or organic chelate form. Nine mature horses were used in a modified switchback design experiment consisting of seven 28-d periods. Horses were fed a diet consisting of 50% concentrate and 50% hay that was balanced to meet the energy, protein, Ca, and P requirements for horses performing moderate-intensity exercise. Horses were subjected to a controlled mineral repletion-depletion diet sequence before feeding the experimental diet to standardize mineral status across horses. The experimental diet was designed to provide 90% of the 1989 NRC for Cu and Zn, with supplemental mineral provided in the inorganic sulfate form (CuSO(4) and ZnSO(4)) or the organic chelate form (Cu-Lys and Zn-Met). Feed, fecal, urine, and water samples collected during a total collection during the last 4 d of the experimental diet periods were analyzed to determine apparent absorption and retention of Cu and Zn from the 2 mineral forms. A formulation error caused horses receiving the organic chelate diet to consume about 3 times the amount of Cu and Zn compared with those fed the sulfate-supplemented diet. Copper and Zn intake and fecal excretion were greater (P < 0.05) for horses consuming the organic chelate-supplemented diet. Apparent absorption values for all horses were negative. Apparent Cu absorption and retention as a percentage of intake were greater for horses fed the organic chelate diet (P < 0.05). It is unknown why excretion of Cu and Zn by the horses during the total collection exceeded the mineral intake. Although Cu-Lys seemed to be better absorbed than CuSO(4) and absorption of Zn-Met and ZnSO(4) were not different, these results are tempered by the observation of abnormally high fecal and urinary excretion values for Cu and Zn in the present study.