Effect of dietary energy levels on the urinary excretion of purine derivatives in sheep

The effect of dietary energy levels on the urinary excretion of purine derivatives (PD) was investigated in sheep fed hay and concentrate diets. In addition, the possibility of using PD concentrations in spot samples of urine as a useful tool for determining daily PD excretion was also examined. Three female lambs (mean bodyweight (BW) ± standard error, 31.4 ± 1.0 kg) were fed three diets consisting of timothy hay (20 g dry matter/kg BW per day) and rolled barley at three different energy levels (low‐energy (LE), medium‐energy (ME) and high‐energy (HE) at 1.0‐, 1.2‐ and 1.5‐fold greater than the maintenance level of energy (450 KJ/BW^0.75/day), respectively) in a 3 × 3 Latin square design. The dietary protein level was almost constant (380 mg nitrogen/BW^0.75/day as digestible crude protein base) and was adjusted using soybean protein. Digestible organic matter intake (DOMI) increased (P < 0.05) with an increase in the dietary energy level and there was a difference (P < 0.05) in the organic matter digestibility between the LE and HE diets. For urinary PD excretion, the differences between the LE and ME diets and the HE diet were significant (P < 0.05), although there was no clear difference between the LE and ME diets. There was a positive correlation (r = 0.47, P < 0.05) between urinary PD excretion and DOMI. There was also a correlation (r = 0.59, P < 0.05) between the urinary PD level at 7–8 h after the morning feed and the daily total PD excretion, suggesting that the PD level in spot urine samples could be useful for estimating microbial protein synthesized in the rumen and/or digested in the lower gut.     

A comparative study on mimosine, 3,4-dihydroxy pyridone (3,4-DHP) and 2,3-dihydroxy pyridone (2,3-DHP), purine derivatives (PD) excretion in the urine,thyroid hormone and blood metabolites profiles of Thai swamp buffalo (Bubalus bubalis) and Murrah buffalo (Bubalus bubalis)

Four Thai swamp buffaloes (SB) and four Murrah buffaloes (MB) fed a based diet of fresh ruzi grass (Bachiaria ruziziensis) with an increased proportion of fresh leucaena leaves. Intake of nutrients in animals increased when ruzi grass was mixed with leucaena. Digestibility of nutrients were the highest in SB and MB fed diets containing 25% and 50% of leucaena, respectively, and nitrogen (N) balances in both animal breeds were varied among diets. The regression equation coefficient of mimosine + DHP in the urine was twice as high in SB than in MB. Urinary purine derivatives excretion rate in SB was higher than that in MB. Plasma triiodothyronine and thyroxine declined in both animal breeds fed a diet containing >1 g mimosine intake/kg BW^0.75/day. Plasma urea–N was the lowest in SB, but the highest in MB when fed a diet containing 84% of leucaena. Plasma β-HBA in SB have declined when diets contained >50% of leucaena but that in MB was not affected by any diet. In conclusion, the effect of leucaena in diet upon buffalo breeds depends on the proportion of leucaena in the diet, mimosine contents and condensed tannins components.     

Intake and digestibility in cattle fed low-quality tropical forage and supplemented with nitrogenous compounds

The effects of supplementation with nitrogenous compounds on intake, digestibility, and microbial protein synthesis in cattle fed low-quality tropical forage were assessed. Five rumen fistulated crossbred Holstein × Gir heifers were used, with initial average live weight of 180 ± 21 kg. Signal grass (Brachiaria decumbens) hay (48.6 g kg⁻¹ of crude protein (CP), on a dry matter (DM) basis) was used as roughage. Five treatments were defined according to nitrogen supplementation level (0, 20, 40, 60, and 80 g of CP kg⁻¹ above the CP level of the hay). A mixture of urea, ammonium sulfate, and albumin at the ratios of 4.5:0.5:1.0, respectively, was used as nitrogen source. The experiment consisted of five experimental periods, according to a 5 × 5 Latin square design. The average CP contents in the diets were 51.9, 71.1, 86.0, 116.7, and 130.2 g kg⁻¹, on a DM basis. A quadratic effect was detected (P < 0.10) of the CP levels in the diets on DM and neutral detergent fiber intake (kg/day), with maximum response at the levels of 102.4 and 100.5 g CP kg⁻¹ DM, respectively. The average daily concentration of rumen ammonia nitrogen showed increasing linear pattern (P < 0.01) as function of CP levels in the diet, with estimated value of 9.64 mg dL⁻¹ equivalent to the maximum DM intake. Microbial nitrogen flow in the intestine was linearly and positively related (P < 0.01) with the CP levels in the diet.     

Faecal nitrogen excretion as an approach to estimate forage intake of wethers

Data from twenty‐two digestibility trials were compiled to examine the relationship between faecal N concentration and organic matter (OM) digestibility (OMD), and between faecal N excretion and OM intake (OMI) by wethers fed tropical or temperate forages alone or with supplements. Data set was grouped by diet type as follows: only tropical grass (n = 204), only temperate grass (n = 160), tropical grass plus supplement (n = 216), temperate grass plus supplement (n = 48), tropical grass plus tropical legume (n = 60) and temperate grass with ruminal infusion of tannins (n = 16). Positive correlation between OMD and either total faecal N concentration (Nfc, % of OM) or metabolic faecal N concentration (Nmetfc, % of OM) was significant for most diet types. Exceptions were the diet that included a tropical legume, where both relationships were negative, and the diet that included tannin extract, where the correlation between OMD and Nfc was not significant. Pearson correlation and linear regressions between OM intake (OMI, g/day) and faecal N excretion (Nf, g/day) were significant for all diet types. When OMI was estimated from the OM faecal excretion and Nfc‐based OMD values, the linear comparison between observed and estimated OMI values showed intercept different from 0 and slope different from 1. When OMI was estimated using the Nf‐based linear regressions, the linear comparison between observed and estimated OMI values showed neither intercept different from 0 nor slope different from 1. Both linear comparisons showed similar R² values (i.e. 0.78 vs. 0.79). In conclusion, linear equations are suitable for directly estimating OM intake by wethers, fed only forage or forage plus supplements, from the amount of N excreted in faeces. The use of this approach in experiments with grazing wethers has the advantage of accounting for individual variations in diet selection and digestion processes and precludes the use of techniques to estimate forage digestibility.     

Feed intake and utilization in sheep fed graded levels of dried moringa (<Emphasis Type="Italic">Moringa stenopetala</Emphasis>) leaf as a supplement to Rhodes grass hay

The effects of feeding graded levels of dried moringa (Moringa stenopetala) leaf on intake, body weight gain (BWG), digestibility and nitrogen utilization were studied using male sheep (BW of 13.8 ± 0.12 kg). Six sheep were randomly allocated to each of the four treatment diets: Rhodes grass (Chloris gayana) hay offered ad libitum (T1), hay + 150 g moringa leaf (T2), hay + 300 g moringa leaf (T3), hay + 450 g moringa leaf (T4) were offered daily. A 7-day digestibility trial and an 84-day growth experiments were conducted. Dry matter (DM), organic matter (OM) and crude protein (CP) intakes increased (P < 0.05) with increasing levels of moringa leaf in the diets. Sheep fed T2, T3 and T4 diets gained (P < 0.05) 40.2, 79.1 and 110.1 g/head/day, respectively, while the control group (T1) lost weight (−13.3 g/head/day). The apparent digestibilities of DM, OM, neutral detergent fibre and acid detergent fibre were similar (P > 0.05) among treatments. The digestibility of dietary CP increased (P < 0.05) with increasing levels of moringa leaf, but there was no significant difference between T2 and T3 diets. The nitrogen (N) intake and urinary N excretion increased (P < 0.05) with increasing levels of moringa leaf. The N retention was highest (P < 0.05) for 450 g moringa leaf supplementation. The control group was in a negative N balance. Supplementing a basal diet of Rhodes grass hay with dried moringa leaves improved DM intake, BWG and N retention. It is concluded that M. stenopetala can serve as a protein supplement to low-quality grass during the dry season under smallholder sheep production system.     

Effects of low-crude protein diets supplemented with rumen-protected lysine and methionine on fattening performance and nitrogen excretion of Holstein steers

The objective of this experiment was to investigate the effects of low-crude protein (CP) diets supplemented with rumen-protected lysine and methionine on growth performance, nitrogen excretion, and carcass traits in Holstein steers. Steers consumed the following diets: (1) 17.2% CP on a dry-matter basis during the early period (from 7 to 10 months of age) and 14.5% CP during the late period (from 10 to 18 months of age; CON, n = 4, initial body weight [BW] 238 kg), and (2) 14.4% CP during the early period and 11.4% CP during the late period (AA, n = 4, initial BW 243 kg). The AA diet contains rumen-protected lysine and methionine. Except for CP intake, feed intake and body weight gain were not affected by dietary CP content. Total nitrogen excretion per metabolic BW tended to be lower (p < .10) in the early period and significantly lower (p < .05) in the late period with decreasing the feed CP content. Plasma urea nitrogen concentrations were lower in AA than CON. Carcass traits and total free amino acid contents of the longissimus thoracis muscle were not affected by dietary CP content. Adding rumen-protected lysine and methionine to a low-CP diet would reduce nitrogen excretion in fattening Holstein steers without affecting productivity.     

Effects of dietary crude protein and tannic acid on nitrogen excretion,urinary nitrogenous composition and urine nitrous oxide emissions in beef cattle

Two consecutive trials were carried out to study the effects of dietary crude protein (CP) and tannic acid (TA) on nitrogen (N) metabolism of beef cattle and consequently, the N₂O emissions from the urine of cattle. In Trial I, eight growing castrated cattle were used as the experimental animals. Two levels of dietary CP (110.6 and 135.7 g/kg dry matter [DM]) and two levels of TA (0 and 16.9 g/kg DM) were allocated in a replicated 2 × 2 crossover design. In Trial II, the N₂O emissions from the urine of cattle collected from Trial I were determined using the static incubation technique. An interaction between dietary CP and TA on the urinary N excretion (p < .05) was found but not on the N₂O‐N emission of cattle urine. Increasing dietary CP level from 110.6 g/kg DM to 135.7 g/kg DM increased the total N excretion (p < .001), the N retention (p < .05) and the ratio of urinary urea‐N/urinary N (p < .01), did not affect the N use efficiency (NUE; p > .05) and shifted the N excretion from faeces to urine. Increasing the dietary CP level increased the N₂O‐N emission of cattle urine. Dietary addition of TA decreased the urinary excretions of urea (p < .001) and shifted the N excretion from urine to faeces, did not affect the NUE of beef cattle (p > .10), and decreased the N₂O‐N emission of cattle urine. Pyrogallol and resorcinol of the TA metabolites were detected in urine with dietary addition of TA. Feeding beef cattle with relatively low CP level and adding TA in rations are effective approaches to mitigate the N₂O‐N emissions from cattle urine.     

Effect of supplementation of indigenous browse tree pods on weight gain and carcass parameters of Abergelle rams

The objective of the study was to evaluate the effect of supplementation of indigenous browse tree pods on nutrient intake, digestibility, weight gain, and carcass parameters of local Abergelle rams fed grass hay as a basal diet. This experiment was conducted at the Abergelle Agricultural Research Center farm in Tigray region, northern Ethiopia. Experimental rams were grouped according to their initial body weight (17.4?±?0.95 kg) in a randomized complete block design into three treatments and six replications. Treatments consisted of feeding grass hay free of choice supplemented with pods of either Acacia tortilis (T₁), Faidherbia albida (T₂), or Dichrostachys cinerea (T₃) fed at the rate of 10 g kg^?1 body weight daily. The crude protein (CP) contents of the supplemental feeds in T₁, T₂, and T₃ were 167, 156, and 135 g kg^?1 dry matter (DM), respectively. The CP intake was significantly higher (P?<?0.05) in T₁ and T₂ than that in T₃. No statistical difference (P?>?0.05) was observed in the digestibilities of DM and CP. Final body weight, average daily gain, slaughter weight (SW), hot carcass weight, and ribeye area were not significantly different (P?>?0.05) among the treatments. However, dressing percentage based on SW in T₁ and T₂ was significantly higher (P?<?0.05) than that in T₃. Therefore, from this research, it can be concluded that though the weight gains and carcass weights of experimental rams were not as such remarkable among the treatments, efficient utilization of locally available and cheap browse tree pods as alternative protein supplements to Abergelle sheep during the dry season could be important to small holder farmers.

     

Influence of dietary crude protein content on fattening performance and nitrogen excretion of Holstein steers

The objective was to investigate the influence of crude protein (CP) content in a fattening diet on feed intake, body weight gain, nitrogen excretion, and carcass traits in Holstein steers. Steers (initial body weight 241 ± 26 kg) consumed feed with the following CP content: (a) 17.7% during the early period (from 7 to 10 months of age) and 13.9% during the late period (from 11 to 18 months of age) (HIGH, n = 3), and (b) 16.2% during the early period and 12.2% during the late period (LOW, n = 4). The CP intake was lower in the LOW than the HIGH group. Urinary and total nitrogen excretion in the late period tended to be lower (p < .10) in the LOW than the HIGH group. However, growth performance and carcass traits were not affected by dietary CP content. Free histidine and total amino acid contents in the longissimus thoracis muscle tended to be higher (p < .10) in the HIGH than the LOW group, however, the CP contents were not affected by dietary CP content. The results of this experiment suggest that decreasing dietary CP to 16% (early period) or 12% (late period) of dry matter would reduce nitrogen excretion from Holstein fattening farms without affecting productivity.     

Supplementation of cottonseed,linseed, and noug seed cakes on feed intake,digestibility, body weight,and carcass parameters of Sidama goats

A digestibility, feed intake, and carcass evaluation experiment using 20 yearling intact male Sidama goats weighing 16.4 ± 0.63 kg (mean ± SD) was conducted in Ethiopia with the objectives to determine feed intake, digestibility, body weight (BW) gain, and carcass parameters. The treatments included feeding natural pasture hay (T1, control) and supplementation with cottonseed cake (284 g—T2), linseed cake (250 g—T3), and noug seed cake (296 g—T4) on dry matter (DM) basis to supply 85 g crude protein (CP) per head per day. Randomized complete block design for feed intake and BW parameters and complete randomized design for digestibility and carcass parameters were used. Hay DM intake was higher (P < 0.01) for T1 than for the other treatments. T3 promoted higher (P < 0.01) DM (29.3 g/kg W^0.75/day) and CP (14.1 g/kg W^0.75/day) intake than T4 (8.9 g/kg W^0.75/day DM and 4.1 g/kg W^0.75/day CP). T3 showed better (P < 0.05) organic matter and CP digestibility than T2. Goats in T3 had higher nitrogen intake (P < 0.01) and retention (P < 0.05) than those in T1. Goats in T2 and T3 showed higher (P < 0.05) daily BW gain and final BW than those in T4 and T1. Goats in T2 and T3 had higher (P < 0.05) slaughter weight, empty BW, hot carcass weight, rib-eye muscle area, and dressing percentage on slaughter weight basis than those in T1. The results showed that T2 and T3 had similar effect on CP intake, daily BW gain, and carcass parameters for growing Sidama goats fed natural pasture hay.     

Establishing an essential amino acid profile for maintenance in poultry using deletion method

This study aimed to estimate the essential amino acid profile and the ideal ratio for the maintenance of poultry by deletion method. A nitrogen balance (NB) trial was conducted using 198 adult roosters, housed individually in metabolic cages. The treatments were 33 purified diets being 11 diets with an amino acid mixture providing high protein intake of 500 mg N/BW_kg^0.75 per day, 11 diets providing medium protein intake of 250 mg N/BW_kg^0.75 per day (in each diet, one amino acid tested was diluted 50%) and 11 diets providing low protein intake of 125 mg N/BW_kg^0.75 per day (made by omitting the amino acid tested). Each treatment had six replicates. After 48 h of fasting receiving water plus sucrose, the roosters were fed 40 g of the diets by tube once a day for 3 days. The excreta were collected within 72 h after the first feeding. The diets and excreta were analysed for nitrogen content. For each amino acid studied, a linear regression was fitted by NB and amino acid intake (AAI). The maintenance requirements were estimated as the AAI to maintain the NB equal to zero. The daily amino acid requirements for maintenance were estimated to be Lys 11, Met 29, Thr 23, Trp 5, Arg 50, Val 29, His 6, Gly 54, Phe 49, Leu 78 and Ile 21 mg/BW_kg^0.75 per day. Therefore, the amino acid ratio for maintenance was concluded to be Lys 100, Met 276, Thr 220, Trp 48, Arg 467, Val 275, His 60, Gly 511, Phe 467, Leu 735 and Ile 198% independent of the scale. The essential amino acid profile and the ideal ratio for the maintenance of poultry estimated in this study contributed to improve the factorial model for estimating essential amino acid requirements for poultry.     

The effect of very low food intake on digestive physiology and forage digestibility in horses

Equid digestion is often conceptualized as a high‐throughput/low‐efficiency system, in particular compared with ruminants. It is commonly assumed that ruminants have an advantage when resources are limited; the effect of low food intake on digestive physiology of horses has, however, not been explored to our knowledge. We used four adult ponies [initial body mass (BM) 288 ± 65 kg] in two subsequent trials with grass hay‐only diets [in dry matter (DM): hay1, mid‐early cut, crude protein (CP) 10.5%, neutral detergent fibre (NDF) 67.6%; hay2, late cut, CP 5.8%, NDF 69.5%], each fed subsequently at four different dry matter intake (DMI) levels: ad libitum and at 75, 55 and 30 g/kg^0.75/day. We particularly expected digesta mean retention times (MRT) to increase, and hence fibre digestibility to increase, with decreasing DMI. Ponies maintained BM on the first, but lost BM and body condition on DMI55 and DMI30. MRTs were negatively correlated to DMI and ranged (for particles <2 mm) from 23/31 h (hay1/2) on the ad libitum to 38/48 h on DMI30. Digestibilities of DM, nutrients and fibre components decreased from DMI75 to DMI30; apparent digestibilities of organic matter and NDF (hay1/2) dropped from 47/43% and 42/37%, respectively, on the ad libitum DMI to 35/35% and 30/28% on DMI30. Additional differences evident between the two hays included a higher estimated ‘true’ protein digestibility for hay1 and finer faecal particles on hay2; there were no differences in faecal particle size between intake levels. The results suggest that below a certain food intake threshold, the major digestive constraint is not fermentation time but nutrient supply to gut bacteria. The threshold for such an effect probably varies between feeds and might differ between ruminants and equids.     

Feed intake,digestibility and body weight change in Farta sheep fed hay supplemented with rice bran and/or noug seed (<Emphasis Type="Italic">Guizotia abyssinica</Emphasis>) meal

The study was conducted to determine the effect of supplementation with rice bran (RB) and /or noug seed (Guizotia abyssinica) meal (NSM) on feed intake, digestibility, and body weight (BW) change in hay based feeding of Farta sheep. Twenty five yearling Farta rams with a mean initial BW of 19.23 ± 0.28 kg were used in randomized complete block design arranged into five blocks of five animals. The five dietary treatments that consisted of hay alone (T₁), hay + RB (T₂), hay + mixture of RB and NSM at a ratio of 1:2 (T₃), hay + mixture of RB and NSM at a ratio of 2:1 (T₄) and hay + NSM (T₅) were randomly assigned to each sheep within a block. The supplements were daily offered at 300 g dry matter (DM) head⁻¹ in two equal parts at 800 and 1600 h. Supplementation improved the total DM and acid detergent fiber (ADF) intake (P < 0.05), organic matter (OM) intake (P < 0.01), crude protein (CP) intake (P < 0.001). The apparent digestibility of DM in T₅ was higher (P < 0.05) than in T₁ and T₂ and that of T₄ was also higher (P < 0.05) than in T₁. The apparent digestibility of CP in T₅ and T₄ were higher (P < 0.001) than in T₁ and T₂ and that of T₃ and T₂ were also higher (P < 0.001) than for T₁. The BW gain of experimental sheep was improved (P < 0.01) by supplementation with NSC (T₅) and/or its mixtures with RB (T₃ and T₄). The results of the study showed that supplementation with either of both mixtures of NSM and RB at 43% of total DM intake promoted better feed intake, digestibility and BW gain in Farta sheep.     

Effects of feed intake on in situ rumen microbial contamination and degradation of feeds

An in situ study was conducted using four rumen cannulated wethers and five feeds (corn grain (CG), soybean meal (SBM), sunflower meal (SFM), vetch–oat hay (VH), and lentil straw (LS)) to determine (using ¹⁵N infusion techniques) the effects of two intake levels (40 and 80 g DM/kg W^0.75) on the microbial contamination and rumen degradation of DM or CP. Degradation studies were also performed for neutral and acid detergent fibres (NDF and ADF, respectively) of VH. In most cases, the evolution with time of the microbial DM adhered to particles fitted well to exponential curves, which diverged between both levels of intake due to the lower values attained at high intake. However, as a consequence of the large and progressive increase of the variability of microbial contamination, statistical evidence is only partial. This behaviour was less evident for CP contamination, especially in forages. The lack of these corrections underestimated (P < 0.001) the effective degradability (ED) of all tested fractions, with important differences between feeds. The intake level had not relevant effects on the distribution of soluble, insoluble available and unavailable fractions of DM or CP (or fibres in VH), but determined some changes in their degradation rates (k_d). Direct relations between these last values and rumen outflow rates (k_p) were shown in some feeds for the degradation of CP and also of DM in concentrates, whereas negative relations were shown for the degradation rates of DM in forages (or NDF and ADF of VH). All ED estimates decreased with the intake rise, but for CP this effect (P < 0.05) was only detected in SBM and VH. These decreases represent 40.8 (CG), 80.8 (SBM), 62.1 (SFM), 66.8 (VH), and 19.5% (LS) than those estimated considering only k_p changes, which shows the interest to consider conjointly the variations of both rates to study the effect of diet changes on ED.     

Effects of intrauterine growth restriction during late pregnancy on the ovine fetal renal function and antioxidant capacity

This study investigated the effects of intrauterine growth restriction during late pregnancy on the ovine fetal renal function and renal antioxidant capacity. Eighteen ewes pregnant were randomly divided into control group (CG, ad libitum, 0.67 MJ ME·BW^−0.75·day⁻¹, n = 6), restricted group 1 (RG1, 0.18 MJ ME·BW^−0.75·day⁻¹, n = 6), and restricted group 2 (RG2, 0.33 MJ ME·BW^−0.75·day⁻¹, n = 6). At 140 days, the fetal blood, allantoic fluid and kidney tissue were collected to determinate fetal renal function and renal antioxidant capacity. The results showed that the fetal weight, kidney weight, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), aquaporin-2 (AQP-2) and aquaporin-3 (AQP-3), and total antioxidant capacity (T-AOC) in RG1 group were decreased compared with the CG (P < 0.05), but the contents of β2-Microglobulin (β 2-MG), cystatin C (Cys-C), filtered sodium excretion fraction (FENa), malondialdehyde (MDA), and hydroxyl radical (OH) in RG1 group were increased (P < 0.05). The impaired ovine fetal renal growth, antioxidant imbalance and dysfunction of glomerulus ultrafiltration, and the renal tubules reabsorption were induced by maternal malnutrition during late pregnancy.     

Net energy content of five fiber‐rich ingredients fed to pregnant sows

The present study was conducted to determine the net energy (NE) values and energy efficiency of wheat bran (WB), sugar beet pulp (SBP), corn gluten feed (CGF), soybean hulls (SBH), and defatted rice bran (DFRB) fed to pregnant sows. Thirty‐six multiparous pregnant sows were randomly assigned to six dietary treatments with six replicates per treatment. Each period lasted for 21 days including 14 days for adaptation. On day 15, sows were moved into respiration chambers for heat production (HP) measurement and provided feed at 544 kJ/kg BW^0.75/day. On day 20, sows were fasted to measure the fasting heat production (FHP). Experimental diets included corn‐soybean meal basal diet and five diets containing 29.20% WB, SBP, CGF, SBH, and DFRB, respectively. Results showed that inclusion of WB, SBP, CGF, SBH, and DFRB to basal diet decreased (p < 0.05) the apparent total tract digestibility of energy and nutrients. The average adjusted total HP and FHP were 418 kJ/kg BW^0.75/day and 326 kJ/kg BW^0.75/day, respectively. The average NE:ME ratio of experiment diets was 82.5%. In conclusion, the NE values of WB, SBP, CGF, SBH, and DFRB were 9.05, 8.59, 8.37, 7.64, and 7.93 MJ/kg DM, respectively.     

Effects of Supplementing a Basal Diet of Chloris gayana Hay with One of Three Protein-rich Legume Hays of Cassia rotundifolia,Lablab purpureus and Macroptilium atropurpureum Forage on Some Nutritional Parameters in Goats

Growth and digestibility experiments were conducted on growing East African type goats offered Chloris gayana hay supplemented with one of three high-protein (119–128 g CP/kg DM) legume hays, Cassia rotundifolia (cassia), Lablab purpureus (lablab) or Macroptilium atropurpureum (siratro), and crushed maize to investigate the feed intake, digestibility, growth and urinary excretion of purine derivatives. Goats in the supplemented groups had higher total dry matter and nitrogen intakes and higher N retention and body mass gains than unsupplemented counterparts. The digestibility of dry matter, organic matter and neutral detergent fibre were increased by protein supplementation. Animals on supplemented diets had higher fractional outflow rates of particulate matter from the rumen. The production of protein by ruminal microbes and the efficiency of microbial N production were increased by supplementation. It was concluded that a mixture of low-quality grass hay (61.9 CP/kg DM) and either cassia, lablab or siratro hay, and maize grain can provide a productive balanced diet for growing goats.     

Comparative Study of Nitrogen Metabolism and the Nitrogen Maintenance Requirement in Lohmann Brown Roosters and Layers

The objective of this study was to investigate the effect of dietary protein level on nitrogen retention and compare nitrogen metabolism in Lohmann Brown adult roosters and layers. The nitrogen maintenance requirement (N_m) was determined based on the nitrogen balance. Thirty Lohmann Brown adult roosters and 30 laying hens at 27 weeks of age were randomly divided into five groups of six birds per group. The birds were fed with one of five diets containing 10.46%, 11.77%, 13.79%, 16.77% or 18.29% of crude protein. Nitrogen intake, nitrogen retention and nitrogen retention efficiency were higher in roosters than in laying hens, and the average nitrogen retention rate for groups fed with CP level of 11.77%, 13.79%, 16.77% and 18.29% was improved by 9.14%. The nitrogen maintenance requirement for Lohmann Brown roosters and laying hens at 27 weeks of age were 0.4245 g/d and 0.5059 g/d, respectively, and Nm based on average body weight (BW) and metabolic body weight (BW^0.75) was 0.2364 g/kg BW and 0.2739 g/kg BW^0.75 for laying hens and 0.2754 g/kg BW and 0.3208 g/kg BW^0.75 for roosters, respectively. The regression equations for daily N gain (N_B, protein accretion) vs. daily N intake (N_I) for Lohmann Brown layers and roosters were N_B = 0.3743N_I–0.1589 (R² = 0.79) and N_B = 0.6228N_I–0.3151 (R² = 0.85), respectively. The results of this study indicate that nitrogen intake and nitrogen retention at the same dietary CP level were higher in roosters than in laying hens.     

Optimal in‐feed amino acid ratio for laying hens based on deletion method

A total of 56 Hy‐line W‐36 hens from 28 to 30 weeks were used on nitrogen balance (NB) trial to estimate daily N maintenance requirements (NMR) and the genetic potential for daily N retention (NR_maxT). The treatments consisted of six graded levels of nitrogen in the diets (N1 = 8; N2 = 16; N3 = 24; N4 = 32; N5 = 40; and N6 = 48 g N/kg of feed), formulated using the dilution technique. The regression analyses between nitrogen intake and excretion were performed to fit the exponential function and to determine the NMR = 292 mg/BW_kg^0.67, which was applied for further calculation of NR_maxT = 1,883 mg/BW_kg^0.67. A second NB trial was conducted, and a total of 96 Hy‐line W‐36 hens were used in the same period to estimate the ideal amino acid ratio (IAAR). Twelve treatments with eight replicates and one bird per cage were used. A balanced diet (BD) was formulated to meet the IAAR and the requirement of other nutrients for pullets. The limiting diets were formulated diluting BD with cornstarch and refilled with synthetic AAs and other feed ingredients, except for the AA under study. In each trial, the data of nitrogen intake, excretion, deposition and retention were obtained in a NB trial. The IAAR determined by Goettingen approach was Lys 100, Met+Cys 88, Trp 21, Thr 69, Arg 109, Val 90, Ile 75, Leu 127, Phe+Tir 110, Gly+Ser 73 and His 29%. The IAAR determined by Louvain approach was Lys 100, Met+Cys 88, Trp 21, Thr 69, Arg 104, Val 91, Ile 78, Leu 121, Phe+Tir 119, Gly+Ser 77 and His 29%.     

Nutritional evaluation of the legume Macrotyloma axillare using in vitro and in vivo bioassays in sheep

This study consisted of two experiments with the following objectives: to evaluate the effects of tannins from the tropical legume macrotiloma (Macrotyloma axillare) on total gas and methane (CH₄) production, as well as on ruminal fermentation parameters by performing an in vitro bioassay, with samples incubated with and without polyethylene glycol (PEG) in a semi‐automatic system; and secondly in a 17 day in vivo experiment, to determine apparent total tract digestibility (ATTD) of dietary nutrients and ruminal fermentation parameters of 12 intact 8‐ to 9‐month‐old Santa Inês (averaging 24.95 ± 1.8 kg body weight) ewes fed tropical grass hay supplemented with macrotiloma hay. The ewes were divided into two treatment groups depending on their diet: chopped aruana grass hay (Panicum maximum cv. Aruana) (control—CON); and aruana grass hay supplemented with chopped macrotiloma hay (macrotiloma—MAC). The animals were kept for 5 consecutive days in metabolic cages for the ATTD assay, and at the end of this period, samples of rumen fluid were collected from each ewe to determine ammoniacal nitrogen (NH₃‐N) and short‐chain fatty acid (SCFA) production, and protozoa count. For the in vitro assay, a decrease in total gas and CH₄ production was observed for samples incubated without PEG (p < .05). No differences were observed for the other parameters evaluated (p > .05). In the in vivo experiment, increased intake and ATTD of crude protein were observed for the animals fed MAC when compared to CON (p < .05). For rumen fermentation parameters, increased NH₃‐N, total SCFA and isobutyrate concentrations, as well as reduced protozoa count were observed for MAC when compared to CON (p < .05). The results observed here indicated the potential of macrotiloma for use as a ruminant feed, and antimethanogenic potential of this plant was noted.