Urea utilization of growing lambs. 2. Growth experiments

In two growth experiments with 30 lambs per group the influence of urea (1-2% of the ration) and straw (20-30% of the ration) on the performance was studied under conditions of intensive fattening. The content of native crude protein in the rations varied between 10.1 and 18.4% of the DM. In experiment 1 the lambs of the two groups which received mixed feed for fattening lambs without urea on average consumed with 1.02 and 1.11 kg DM resp., 696 and 757 EFUcattle resp. and 173 and 189 g crude protein resp. per animal and day. The groups with wheat or barley and urea consumed 1.06 and 0.96 kg DM resp., 714 and 627 EFUcattle resp. and 209 and 155 g crude protein resp. Their weight gain of 247 g/animal and day was 24% and that of 230 g resp. 26% higher than that in the control groups without urea. The lowest dry matter intake (0.91 and 0.82 kg resp.) was shown by the animals of the groups which received wheat or barley without urea. In the second experiment the control group achieved an average daily weight gain of 327 g at an expenditure of 2.24 kEFUcattle/kg weight gain. Despite a partly higher dry matter intake, the daily EFUcattle intake was between 12.2 and 24.5% lower in the straw groups and energy expenditure increased between 12.0 and 27.8%. Urea supplements of between 1 and 2% improved dry matter, EFUcattle and crude protein intake and thus weight gain.     

Urea utilization in growing lambs. 4. N balances with unprocessed rations

N balance experiments were carried out with lambs of the ages of 8, 12 and 15 weeks fed with wheat rations with and without 2% urea supplement (N 1 and N 2) as well as with 3% urea and 20% straw (N 3) or with a soya bean meal supplement (N 4). There were no significant differences in the digestibility of the crude nutrients and in per cent of N retention between the individual ages. The straw supplement decreased the digestibility of organic matter, crude protein, crude fibre and NfE. The supplements of soya bean meal or urea increased the crude protein content in comparison to the wheat ration without supplements by 6% in the dry matter and resulted in N intakes 55 ... 60% higher and in 23 ... 38% higher N retention, which was, however, lower in relation to N intake. There were no significant differences with regard to N retention between N 2, N 3 and N 4. Consequently urea supplement to the feed mixture with 14% native crude protein resulted in increased N retention, which was not lower than with a soya bean meal supplement.     

Urea utilization by growing lambs. 5. N-balance with half synthetic rations

In experiment with 14-week-old lambs a combination of semisynthetic rations containing 1.2% or 0.7% resp. native crude protein an intraruminal infusion of urea clearly influenced the biologic processes in the rumen. The molar quotas of butyric and valeric acid in comparison with acetic were high. The lambs could cope with infused amounts of 0.67 g urea/kg body weight if they received the daily amount of 1.35 g/kg body weight in two parts. When more than 1.9 g/kg body weight were applied, feed intake decreased even though the daily amount was distributed over 4 doses. In 10 out of 16 lambs N retention was, in dependence on the urea amounts infused, higher than the N amount retained from native crude protein. The result indicates that urea is utilized by 14-week-old lambs. Growing energy and N intake had a positive influence on the N balance.     

Urea utilization in growing lambs. 6. N balance with 15N urea

Lambs of an age of 2 or 4 months and of an average live weight of 14.7 and 27.4 kg resp. received rations consisting of 44% cereals, 46% dried sugar beet pulp, 6% wheat starch, 2% urea and 2% mineral-vitamin mixture. The crude protein content was 17.1 and 15.9% resp. in the dry matter, that of native crude protein 10.6 and 9.4% resp. During a 6-day N balance period 8 and 16 g 15N urea resp. with a 15N excess (15N') of 9.26 and 9.40 atom-% were fed orally instead of commercial feeding urea. There were no significant differences between the two age groups with regard to the digestibility of the organic matter and the crude nutrients. The average N balance of 372 +/- 85 mg/kg LW 0.75/day were in the intermediate range of N retention capacity and accounted for 26 +/- 5% of the consumed N. N retention in per cent. was slightly lower in younger lambs. Projections of urea utilization in a quasi stationary state resulted in an efficiency of the utilization of 33 +/- 4%. The dismembering of the lambs at the end of the main period showed between 0.02 and 0.22 atom-% 15N' in the total N, TCA precipitable N and amino acid N of the meat. At between 0.24 and 0.38 atom-% 15N' they were highest in the heart and jaw muscles. The quota of 15N' amounts found in the total N of the meat were 10.6 +/- 3% of the 15N-intake and 20.1 +/- 5.1% of the 15N' amount remaining in the body. The bones contained 7.7 +/- 1.7% and the fleece 7.9 +/- 3.1% of the 15N'-intake. Generally seen, the total N and urea utilization was slightly lower in younger lambs than in older ones.     

Urea utilization in growing lambs. 3. Effect of urea and straw on carcass composition

Subsequent to a growth experiment with intensively fattened lambs the value of the carcasses of 4 animals each from 7 groups was determined. The control groups with mixed fattening feed for lambs and the groups with wheat and barley mixtures containing urea showed higher carcass yields, net gains, fat percentage and padding, dry matter and fat content of the carcass and lower quotas of important cuts as well as a lower crude protein content in the carcass than groups with grain without urea and groups with straw. This is due to the higher weight gains of the first-mentioned groups. There were no significant differences in the carcass characteristics between the animals of the control group and the grain-urea groups. The carcass quality of the male lambs was better than that of the female ones.     

Nitrogen utilization in growing lambs: effects of grain (starch) and protein sources with various rates of ruminal degradation

The potential interaction between grain (starch) and protein sources with varying ruminal degradation rates on N utilization in growing lambs was evaluated. Three grain sources with varying ruminal degradation rates, (barley greater than steam-flaked sorghum [SFSG] greater than dry-rolled sorghum [DRSG]) and three protein sources (urea greater than a 50:25:25 mixture of urea: blood meal:corn gluten meal [N basis, U/BC] greater than 50:50 mixture of meal:corn gluten meal [N basis, BC]), were evaluated in a 3 x 3 factorial arrangement. Supplemental protein sources provided 33% of dietary N (CP = 11.0%). For each grain-protein combination, a 3 x 3 Latin square metabolism trial was conducted using two sets of three lambs and three periods. Within-square treatments were 1.4, 1.7 and 2.0 times maintenance intake levels. No interactions were observed (P greater than .2) between dietary treatments and intake level. Grain sources did not differ (P greater than .2) in N balance or the proportion of N retained. Lambs fed urea diets retained less N (3.6 vs 4.2 and 4.1 g/d for urea vs U/BC and BC, respectively; linear, P = .07; quadratic, P = .12) and utilized N less efficiently (43.1 vs 51.9 and 52.5%, respectively; linear, P less than .001; quadratic, P = .10) than lambs fed BC diets. The grain x protein interaction was significant for most variables. Nitrogen utilization was most efficient (24 to 27% of N intake retained) when rapidly degraded sources (barley and urea) and slowly degraded sources (sorghum and BC) were fed together or when U/BC was the supplemental protein source (interaction P less than .08). An advantage was found for selection of starch and protein sources with similar ruminal degradation rates.     

Effects of ruminal escape proteins and canola meal on nitrogen utilization by growing lambs

The effects of ruminal escape proteins and canola meal (CM) on N utilization by growing lambs were evaluated in two experiments. In both experiments, seven supplemental dietary protein treatments were fed. For each of these protein treatments a 3 x 3 Latin square metabolism trial was conducted, using two sets of three lambs and three periods. Within square treatments were 1.4, 1.7 and 2.0 times maintenance intake levels. In Exp. 1, protein treatments were control (7.0% CP, DM basis), urea fed at 9.5 or 12% dietary CP, CM fed at 9.5 or 12% dietary CP and a 50:50 (N basis) mixture of blood meal/corn gluten meal (BC) fed at 9.5 or 12% dietary CP. In Exp. 2, protein treatments were urea, 64% urea and 36% BC (all mixtures on a N basis), 36% urea and 64% BC, BC, 50% CM and 50% BC (CM/BC), CM and soybean meal (SBM), all at 10.5% CP. In Exp. 1, apparent N digestibility (AND) was lower for CM diets than for urea (P = .13) and BC (P less than .05) diets (49.0 vs 50.6 and 51.3%, respectively). Absorbed N was utilized with similar efficiencies for all supplemental protein sources. Dietary CP and digestible protein (DP) were closely related (DP = .879[CP%] -3.66; r2 = .91), indicating that for urea, CM and BC total tract N digestibility was not influenced by theoretical ruminal degradability. In Exp. 2, N balance and N utilization efficiency indicated that the optimal extent of ruminal protein degradation was about 50%. Nitrogen balance was similar for the CM, CM/BC and SBM treatments.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of energy concentration and source on the utilization of feed protein and NPN in lambs. 2. 15N balance and utilization of pure protein and NPN

In an experiment 12 lambs of the merino species were divided into 4 groups. The variants HE received 740 or 718 EFU cattle/kg DM and the variants NE 689 or 671 EFU cattle/kg DM. The different energy concentrations resulted from differentiated quotas of dried sugar beet chips and wheat starch supplements. Within the variants, sub-variants with (HESZ, NESZ) or without (HES, NES) sugar supplements were formed. Due to varied DM intake, the average energy intake in all groups was 42 EFU cattle/kg LW0.75. N balance experiments using 15N-labelled urea were carried out, and 15N accumulation of N excretion was projected to a steady state. The partial utilization of pure protein and NPN in the ration was ascertained with the help of a 3-pool compartment model of N utilization in ruminants. In the non-amino acid N pool HE utilized 84% of NPN and NE 77% for the synthesis of amino and nucleic acids. The efficiency of protein synthesis in the amino acid N-pool were in HESZ 64%, HES 70%, NESZ 70% and NES 73%, resp. The total utilization of NPN is the sum of the partial utilization in the two pools, whereas the total utilization of pure protein is calculated from the true digestibility and the efficiency of the utilization in the AA-N pool. The total utilization of NPN for the synthesis of protein for the protein pool amounted to 40/35/41/33% and that of pure protein to 54/51/49/50%. Energy intake being identical, energy concentration did not have an influence on the utilization of pure protein and NPN, whereas NPN utilization was better in rations containing sugar. The pure protein in the ration was by 19 ... 52% better utilized than NPN.     

Nutrient and energy retention in growing lambs. 1. Results of growth experiments

The results of a growth experiment are explained which was carried out as basis for the control slaughtering method and for N-balance experiments with hybrid fattening lambs of both sexes and of three different genetic constructions in comparison with male merino mutton lambs. The animals were kept individually on perforated floor and received pelleted fattening feed for lambs ad libitum. In the live weight range between 15 and 30 kg the male hybrid lambs reached significantly higher live weight gains than the merino mutton sheep, the former tending towards higher feed intake and lower energy expenditure. The male hybrid lambs showed a significantly higher live weight gain and a significantly lower energy expenditure than the female animals of equal live weight whereas there were no differences between the sexes in feed intake.     

Tryptophan requirement of growing pigs at various body weights

The purpose of this study was to determine the tryptophan (Trp) requirement of growing pigs at different body weight (BW) ranges. Three performance experiments were conducted with female pigs in the BW ranges of 25-50, 50-80 and 80-115 kg. In addition to the performance experiments, nitrogen balance experiments were carried out in which pigs weighing 56, 66 and 86 kg were used. Trp-deficient basal diets were formulated to which varying amounts of l-Trp were added. The amino acid concentrations of the diets were analysed; concentrations of standardized digestible amino acids were calculated on the basis of tabular values. The calculated concentrations of standardized ileal digestible tryptophan were 0.81, 1.11, 1.41, 1.71, 2.01 g/kg diet in the lower BW range (25-50 kg), 0.71, 0.96, 1.21, 1.46, 1.71 g/kg diet in the middle BW range (50-80 kg), and 0.49, 0.69, 0.89, 1.09, 1.29 g/kg diet in the upper BW range (80-115 kg). Dose-response relationships were evaluated by means of an exponential regression model. In all three age ranges, performance parameters as well as nitrogen retention were strongly influenced by the dietary concentration of standardized ileal digestible tryptophan. According to the exponential model, in the 25-50 kg BW range, 95% of the maximum feed consumption, BW gain and nitrogen retention were achieved at concentrations between 1.96 and 2.00 g of standardized ileal digestible Trp per kilogram diet, corresponding to 3.32-3.39 g/day. In the BW range of 50-80 kg, 95% of the maximum of these parameters occurred at concentrations of standardized ileal digestible tryptophan in excess of the highest concentration of 1.71 g/kg diet, corresponding to 3.71 g/day. In the BW range of 80-115 kg, 95% of the maximum of BW gain and nitrogen retention were recorded at concentrations of 1.22 and 0.84 g standardized ileal digestible Trp per kilogram diet, corresponding to 3.77 and 2.25 g/day, respectively. Related to the energy value of the diets, the optimal concentration of standardized ileal digestible tryptophan are between 140 and 143 mg/MJ metabolizable energy (ME) in the BW range of 25-50 kg, in excess of 127 mg/MJ ME in the BW range of 50-80 kg and between 62 and 90 mg/MJ ME in the BW range of 80-115 kg. In conclusion, it is suggested that the requirement of standardized ileal digestible tryptophan for growing pigs might be higher than currently assumed.     

Pathological and biochemical studies on experimental hypothyroidism in growing lambs

Secondary iodine deficiency was experimentally produced in growing male lambs by oral administration of 50 mg/kg bodyweight of Thiourea daily for 3.5 months. At the end of the experiment the animals became weak, emaciated, anaemic, significantly reduced in body weight with facial oedema and alopecia at thigh, legs and abdomen. The clinical analysis showed significant reduction in erythrocyte and leucocyte numbers and in levels of triiodothyronine and testosterone at the end of the experiment. The histopathological picture of the thyroid gland revealed hyperplasia of the follicle-lining epithelial cells which project into the lumen. The lumens of the follicles are devoid of colloid. The testes showed ill-developed small, empty seminiferous tubulcs. In the liver, the hepatocytes showed degeneration and vacuolation with proliferation of Kupffer cells, which contain haemosiderin pigment. The kidney showed glomerular lipidosis with accumulation of haemosiderin pigment in the cytoplasm of the renal tubules. Hyperkeratosis of the epidermis associated with excessive keratin formation within the hair follicles was detected. In conclusion, deficiency of iodine causes hypothyroidism which leads to retardation of growth, reduced wool production and interferes with sexual maturity of growing male lambs.     

Energy and protein utilization in growing cattle

Limited data are available to describe the different phases of dietary protein and energy utilization in growing cattle as compared with those in adult cattle or in growing nonruminants. The European data on this topic are summarized to indicate application in appropriate feeding standards. Net protein requirements are widely variable with breed and sex. They are lower in steers than in bulls and lower in early maturing than in late maturing breeds. They are clearly defined for growing and fattening bulls where they are influenced by breed, live weight and live weight gain. New systems have been proposed to express the protein allowances. They provide a great step towards a concept explaining N supply to ruminants. However, protein degradability in the rumen, efficiency of microbial protein synthesis, intestinal digestibility and metabolic efficiency of amino acid absorption in the intestine need to be described more accurately. Even if body energy retention measured by the slaughter technique is systematically lower than when measured by calorimetric balance, both techniques can correctly describe the effect of breed sex, weight, or daily gain on energy retained, in relative value, and its distribution between protein and fat deposition. But further research is needed to confirm the distribution of metabolizable energy between maintenance and growth and the efficiency of metabolizable energy utilization for growth. Thus, different authors have preferred to calculate the energy allowances, not by a factorial method, but by regression between energy intake and the corresponding weight and daily gain of animals measured during feeding trials.     

Anthelmintic effects of Salix babylonica L. and Leucaena leucocephala Lam. extracts in growing lambs

Twenty Katahdin?×?Pelibuey crossbreed male lambs, 3 to 4 months of age and 24?±?0.3 kg of body weight, were used to study the anthelmintic effects of administering extracts of Salix babylonica L. (SB) and Leucaena leucocephala Lam. (LL). Lambs had not been treated with anthelmintics previously and were randomly allocated into four groups of five lambs each in a completely randomized design. Treatments were as follows: control (lambs fed on total mixed ration without extracts), SB (as control plus S. babylonica L. extract at 30 ml/day), LL (as control plus L. leucocephala Lam. extract at 30 ml/day), and SBLL (as control plus 30 ml/day of S. babylonica L. and L. leucocephala Lam. extracts in a 1:1 (v/v) mixture) for 63 days. Extracts were orally administered before the 8:00 a.m. feeding to each lamb. Rectal fecal samples were collected from each lamb at day 22 (P1), day 43 (P2), and day 63 (P3) of the experiment. Adult worm and egg counts were determined in each fecal sample immediately after collection. Plant secondary metabolites of total phenolics, saponins, and the aqueous fraction were 50 % lower in the SB versus LL extracts. Overall, the oral administration of extracts has improved the egg and worm count reductions in lamb feces by 54, 47, and 40 % for LL, SB, and SBLL, respectively, versus the control lambs. Reductions of worm egg counts in lamb feces were higher (P?<?0.05) in P2 and P3 versus P1. Extracts of SB and LL or possibly isolated bioactive compounds could be a promising alternative to conventional anthelmintics to treat gastrointestinal parasites of small ruminants. Such treatments could be used in control strategies against gastrointestinal nematodes in organic and conventional production systems.     

Source and level of supplemental protein for growing lambs

Two 3 x 2 factorial growth trials and a companion metabolism trial with 13, 15, or 17% dietary CP (DM basis), with or without 3% of the DM replaced with slowly degraded menhaden fish meal, were conducted to determine if level of dietary protein influences whether slowly degraded protein improves lamb growth and protein use. The growth trials included 32 and 34 pens of two weanling lambs initially weighing 23 to 26 kg and fed for 42 d. The metabolism trial included 12 additional lambs fed in metabolism cages with a 2-wk adjustment period, a 1-wk preliminary period, and a 7-d collection period. Plasma urea N (PUN) was measured in all lambs at the conclusion of the second growth trial and at the end of the metabolism trial. There was a protein level x protein source interaction (P = 0.05) for PUN of the 12 lambs in the metabolism trial but not for the 68 lambs in the second growth trial. Replacement of part of the soybean meal protein with protein from fish meal did not affect ADG or G:F at any protein level, but it lowered (P = 0.08) PUN in the second growth trial. Plasma urea N values were higher (P = 0.002) in lambs fed diets with 15 or 17% CP; however, ADG (P = 0.037 in Exp. 1 and P = 0.055 in Exp. 2), and G:F (P = 0.094 in Exp. 1 and P = 0.003 in Exp. 2) were lower for lambs fed the diets with 13% CP. There was little difference in ADG or G:F between lambs fed the diets with 15 or 17% CP, suggesting that a CP level of 15% with supplemental protein from soybean meal would be optimal for 25- to 40-kg growing Finnsheep x Dorset lambs.     

Condensed tannins and nutrient utilization by lambs and goats fed low-quality diets.

In the first of two experiments, four wether lambs (BW = 26.8 kg) and four wether Angora goats (BW = 31.7 kg) were used in two simultaneous 4 x 4 Latin squares to study the influence of condensed tannins (CT) on nutrient usage and concentrations of serum urea N, somatotropin (GH), and insulin (INS) when the animals were fed low-quality diets containing mountain mahogany (MM; Cercocarpus montanus) leaves. Diets were 8% CP and contained 25% or 50% MM (with hay or straw, respectively), either untreated or treated with polyethylene glycol (PEG; molecular weight 3,350) to reduce total reactive CT. Diets treated with PEG and 25% MM diets had less (P less than .05) CT than diets without PEG or those with 50% MM. Diets containing 50% MM resulted in greater N balance and lower serum urea N (P less than .01) than 25% MM diets. Concentrations of GH and INS were similar in animals fed the 25% and 50% MM diets. Reducing CT by adding PEG did not affect N balance or improve nutrient digestion by lambs or goats fed low-quality diets. In Exp. 2, four wether lambs (BW = 28.4 kg) were used in a 4 x 4 Latin square and fed the same diets as animals in Exp. 1 to study the influence of CT on ruminal fermentation and digesta kinetics. Dietary PEG treatment did not affect digesta kinetics except for a 30% increase in ruminal volume; 50% MM diets had faster particulate passage rates (P less than .05) than 25% MM diets. Ruminal ammonia N was greater (P less than .01) in lambs fed PEG-containing or 25% MM diets; however, rate of in situ NDF disappearance was not reduced by the lower ammonia N in the latter diets.     

Water consumption in piglets weaned early at various ages and fed a liquid diet]

Water consumption was recorded in 72 piglets of the Lorge White breed, weaned either on the second, sixth, tenth day or on the fourteenth day of age, this parameter was followed till the age of four weeks. The piglets were kept individually in a thermoneutral zone and they received a milk diet with macronutrient content, similar to sow's milk and water content of from 78.47%. The diet was offered to suck nine times a day in two-hour intervals. The piglet age at weaning was found to influence significantly water intake. Daily water ingestion is higher in piglets separated from the sows at a younger age than in piglets weaned later on; it reaches as much as 29% in the first group, 26% in the second group, 28% and 20% of live weight in the third and fourth groups, respectively. If converted to the metabolic weight, the percentage is still higher: more than 40% in the first group at the end of the fourth week. Although the spans of weaning beginnings were always identical in particular groups of piglets (four days), the differences in the water consumption were not the same. The differences were smaller between the first and second group, and the third and fourth group, in comparison with those between the second and third group. This fact confirms previous general statements about the periodization of early postnatal life of piglets. The beginning of weaning of the first two groups belongs to the "suckling" period, while the beginning of weaning of the other groups is within the "weaning" period.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of Haemaphysalis punctata infestation on growing lambs and rabbits

Lambs infected with adult Haemaphysalis punctata and rabbits infected with nymphs developed a macrocytic normochromic anaemia during seven and six successive infestations, respectively. The anaemia was directly proportional to the degree of infestation but disappeared several days after the termination of infestation. A leucocytosis, due to neutrophilia, was seen in both lambs and rabbits. Rabbits developed a thrombocytosis and reticulocytosis. Infested lambs grew less rapidly than uninfested animals. Signs of tick toxicosis and several other clinical manifestations appeared in both infested sheep and rabbits. Circulating antibodies against salivary antigen of adult H punctata were demonstrated in the sera of infested lambs by the micro-ELISA test. Titres were first detected on day 3 after infestation and increased gradually as infestation progressed. No precipitating antibodies in either infested sheep or rabbits were detected.