Performance of Zebu Steers Grazing on Western Tanzania Native Forages Supplemented with <Emphasis Type="Italic">Leucaena Leucocephala</Emphasis> Leaf Meal

Information is lacking on the potential of leguminous fodder trees such as Leucaena leucocephala as a feed resource to supplement the native forages in traditional grazing management systems in the tropics. Two studies were conducted (1) to assess traditional fodder banks’ forage nutritive potential on animal production, and (2) to investigate the effect of Leucaena leucocephala leaf meal (LLM) supplementation on growth of steers grazing standing hay basal forages in the dry season. The traditional forages had low nutritive values indicated by low mean crude protein (CP) of 23 g kg⁻¹ dry matter (DM), and high fibre contents of 717, 546 and 153 g kg⁻¹ DM for neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL), respectively. The forages were poorly degraded in sacco and had low metabolisable energy (ME) (4.2–4.6 MJ kg⁻¹ DM). Mean washing losses A, slowly degradable DM fraction, B, potential degradability, (A+B) and mean 48 h DM degradability (DMD) of grazing land forages were 70, 471, 541 and 326 g kg⁻¹ DM, respectively. In the supplementation study, 16 growing steers (160.8±0.24 kg) were randomly allocated into four groups, in a completely randomized design. Four LLM treatment diets (T1, T2, T3 and T4), with four levels: 0, 0.4, 0.6 and 0.8 kg DM for control, low, medium and high LLM levels, respectively, were randomly allocated to the animals in the four groups for 70 days (d). LLM supplementation (p<0.05) improved mean weight gain from −0.30 to 0.26 kg steer⁻¹ d⁻¹, for T1 and T4, respectively. Steers on T4 gained (p<0.05) more weight compared to the animals in T1 and T2, though there was no (p>0.05) difference in weight gains between animals on T3 and T4 (0.14 vs. 0.26 kg steer⁻¹ d⁻¹, respectively). Standing hay basal forages alone could not sustain animal productivity during dry seasons unless corrected for protein. Higher levels of LLM supplementation prevented weight losses and improved the performance of grazing steers, a management practice thought appropriate to low income pastoralists in semiarid western Tanzania.     

Gliricidia sepium as an alternative protein supplement to cottonseed cake for smallholder dairy cows fed on Napier grass in Tanzania

Lack of availability, poor quality forages and cost of concentrate feeds, especially during the dry season, are some of the major problems faced by smallholder dairy producers in the tropics. Therefore, two experiments were conducted to evaluate the nutritive value and economic benefits of substituting cottonseed cake (CSC) by Gliricidia sepium (GS) for milk yield and composition of crossbred dairy cattle. In experiment one chemical composition of the two feeds and their dry matter degradability (DMD) were determined. GS had (P < 0.05) higher dry matter degradability (DMD) than CSC. Potential DM degradability (PDMD) and degradation rate constants (c) of CSC and GS did not vary (P > 0.05). In experiment two, four treatment diets, all based on Napier grass, maize bran, mineral/vitamin mixture and two levels each of GS and CSC, were fed to milk cows in a 4 × 4 Latin square experiment. The treatments were, T1 = 0 GS + CSC 18%, T2 = 18% GS + CSC, T3 = 23.4% GS + CSC and T4 = 39.7% GS + CSC. Cows on T1 and T3 showed (P < 0.05) higher total DMI, metabolizable energy intake (MEI) and milk yield than cows on T2 and T4. There were no differences (P > 0.05) in milk protein, butterfat and total solids contents between the treatments. Cost analyses showed diet T3 to be more profitable than the other treatments, suggesting that the use of GS in combination with CSC is more profitable than when either of the two was used alone.This revised version was published online in November 2005 with corrections to the Cover Date.     

Improving rumen fermentation and milk production with legume-tree fodder in the tropics

Feeding leguminous fodder that is high in protein can improve rumen fermentation parameters leading to increased digestibility and intake of low quality fibrous feeds, and hence improved animal production. The effect on dry matter (DM) degradation and rumen fermentation parameters of feeding urea or tree legume foliage (Erythrina poeppigiana or Gliricidia sepium), as protein supplements to a basal diet of Hyparrhenia rufa hay, rice bran and molasses, was studied with rumen fistulated steers (Zebu × Creole crossbreeds). In a second experiment, Jersey × Creole crossbreeds were used to determine the effect of the above three treatments on milk production. Both experiments were conducted at CATIE's experimental farm, Turrialba, Costa Rica (9°58 N; 83°31 W; 639 m above sea level; mean annual precipitation of 2600 mm; mean daily temperature 22 °C). The disappearance of hay DM in the rumen increased with time to 144 hours and potential degradation of hay DM was significantly higher (P < 0.05) for the legume diets compared to urea but there were no differences between legume species. Legume based rations resulted in total volatile fatty acid concentrations of rumen licor that were 15 to 24% higher than for urea based rations (P < 0.05). The concentration of rumen NH₃-N was highest two hours after feeding and tended to decrease in time. The urea ration resulted in significantly higher NH₃-N than the legume rations, reaching 45 mg/100 mL two hours after feeding. Milk yields did not differ (P > 0.05) when cows received either E. poeppigiana or G. sepium foliages as protein supplements (7.3 and 7.4 kg milk/cow/day, respectively) but they were superior (P < 0.05) to urea supplementation (6.7 kg milk/cow/day).     

The Potential of Albizia lebbeck as a Supplementary Feed for Goats in Tanzania

Forty growing goats (20 males and 20 females) were used in a 90-day growth and intake study to evaluate the potential of Albizia lebbeck (ABC) based concentrate as compared with Gliricidia sepium (GBC), Leucaena leucocephala (LBC), and Moringa oleifera (MBC) based concentrates with cotton seed cake (CSC) as a control. The animals were fed a basal diet of maize stover and supplemented daily with 30 g/kg W^0.75 of ABC, GBC, LBC, MBC, and CSC. They were compounded so as to formulate iso-protein diets. Treatment effects were significant (p<0.05) for growth rates in that with the exception of GBC, goats on CSC exhibited significantly higher gains compared to counterparts in other treatments. The total DM intake was between 50.6 and 52.6 g/kg W^0.75/day and there were no significant (p>0.05) differences among treatments. There were significant differences (p<0.05) among treatments for maize stover intake. CSC based treatment showed the highest intake with insignificant (p>0.05) differences amongst the leaf meal based concentrates. It can be concluded that Albizia lebbeck had similar potential to the other leaf meal based supplements studied but had lower potential compared to a cotton seed cake based supplement, as protein sources for growing goats fed a poor quality basal diet.     

Ruminal Fermentation and Nutrient Digestion in West African Dwarf (WAD) Sheep Fed Leucaena leucocephala Supplemental Diets

Dry season feeding has always posed a problem for ruminant nutrition in sub-Saharan Africa. The availability of browse plants or multi-purpose trees during this period has led to their incorporation in the farming systems. The need therefore to investigate the feeding value and fermentation profiles of WAD sheep fed grass hay with supplemental Leucaena leucocephala formed the objective of this study. Eight 18–24 months old West African Dwarf (WAD) sheep (28.8±4.2 kg body weight) were used in the study. Four of the sheep were fistulated ruminally and rumen pH, ammonia and volatile fatty acid were measured. Dried leaves of L. leucocephala were offered at two levels (25 and 50% of DMI, diets D25% and D50%, respectively) as supplement to a basal hay diet. The basal hay diet without supplement was the control diet. Diet D25% had a higher (p <0.05) ruminal ammonia concentration than the control, while diet D50% had a higher (p <0.05) total volatile fatty acid (VFA) concentration compared to both the control and D25% diets, respectively. Diet D25% had a marginal increase of 6.7% N- retention over the control diet. Organic matter digestibility (OMD) decreased (p <0.05) with level of supplementation. Animals on D50%, D25% and the control diets lost 14, 7.3 and 5%, respectively, of retained energy leading to a negative energy balance. Overall results suggest that a 25% level of supplementation with leucaena gave the best outcome even though a range of 25–50% could be fed during periods of basal diet scarcity.     

Potential contribution of <Emphasis Type="Italic">Quercus durata</Emphasis> and <Emphasis Type="Italic">Adenostoma fasciculatum</Emphasis> supplemented with <Emphasis Type="Italic">Medicago sativa</Emphasis> on intake and digestibility in sheep and goats

A digestion trial was conducted to estimate the potential contribution of the chaparral browse Quercus durata (leather oak) and Adenostoma fasciculatum (chamise) on intake and nutrient digestion in goats and sheep. Four wether Kiko goats (avg. wt. 22.9 kg) and four wether Targhee sheep (avg. wt. 39.6 kg) were housed in metabolism cages. Alfalfa pellets were used as a dietary supplement. Digestibility of the shrubs was measured by difference and metabolizable energy (ME) and ME intake (MEI) were calculated from digestibility and plants intake values. Oak and chamise had low crude protein (CP) content (6.5 and 4.3% DM) and high content of extractable condensed tannins (17.8 and 9.8% DM). In vitro organic matter digestibility (OMD) and ME for oak and chamise were 35.6 and 33.1% and 5.0 and 4.7 MJ/kg DM, respectively. In vivo OMD (calculated by difference with alfalfa) and MEI, for browse were greater (P < 0.01) for goats fed chamise compared to sheep. In oak, OMD was similar for both animal species but MEI was greater (P < 0.01) for goats. Greater (P < 0.05) DM and CP intakes (per kg BW^0.75) were observed for goats fed either oak or chamise compared with sheep. When an energy source was given as supplement, the potential contribution of chamise and oak to total ME requirements for maintenance was about 58.3 and 60.4% in goats and about 17.1 and 32.9% in sheep, respectively. In consequence, metabolizable energy supplied by these shrubs may not be adequate for maintenance when, during grazing, they are consumed in high proportions with other chaparral plants that may have lower nutritional value than the alfalfa supplemented in this study. Under an appropriate supplementation program, goats could be more effective than sheep to control fuel load in California chaparral, as they consume more chamise and leather oak and obtain more nutrients from them.     

Intake,digestibility, nitrogen balance and certain rumen characteristics of Ethiopian Menz sheep fed teff straw supplemented with cotton seed cake,dry sesbania,dry leucaena or fresh leucaena

Twenty five rumen fistulated Ethiopian Menz sheep were used in a completely randomized block design to determine roughage utilization when different types of supplements (sesbania, leucaena, cotton seed cake (CSC)) and forms (fresh or dry leucaena) were fed. The chemical composition, intake, digestibility, nitrogen balance and rumen degradability coefficients were determined. Rumen pH and ammonia-nitrogen (NH₃-N) levels were estimated in samples taken at 1, 2, 3, and 6 h after feeding.There was substitution of teff straw dry matter by the supplements. Fresh leucaena effected the highest substitution. Supplementation enhanced (p<0.05) the dry matter degradation (DD) of teff straw at 6 and 12 hours of incubation but not (p>0.06) for the other incubation times. There were no significant differences (p>0.05) between treatments in the degradation constants: readily soluble component (a) slowly degradable fraction, (b) potential degradability (PD=a+b) and rate of degradation (C) and for rumen NH₃-N concentration, the ranking was CSC > sesbania > dry leucaena > fresh leucaena > teff straw alone (p<0.05). The particularly high substitution rate observed with fresh leucaena might suggest that bulkiness may be a limiting factor in the intake of low quality roughages supplemented with tree leaves. The lower DM and OM digestibilities of the supplemented diets were attributed to substrate preference by rumen cellulolytic bacteria. Excessively high levels of rumen NH₃–N (328 mg/l) in the CSC diet resulted in high urinary nitrogen losses (r ²=0.32;p<0.001) leading to low N balance. This may suggest that for the utilization of poor quality tropical roughages, moderate levels of rumen NH₃–N sustained over a longer period may be needed.     

Effect of low-protein diet with supplementing different levels of DL-methionine on production performance of minks in growing-furring period

A study was conducted to evaluate production performance of minks in growing-furring period with supplementing DL-Methionine (Met) in low protein diet. Seventy healthy male minks were randomly divided into five groups of 14 minks each. The minks were fed in five kinds of experiment diets (HP, LP, LP+M1, LP+M2 and LP+M3). The dietary protein levels, expressed as percentage of dry matter (DM), were 32% (high protein, HP) and 24% (low protein, LP). LP was supplemented with Met 0.4% (M1), 0.8% (M2) and 1.2% (M3) DM. From mid of September to December 10, apparent digestibility of CP (crude protein), N intake and urinary N excretion were decreased with declining dietary protein levels (p < 0.05) and N retained was the highest in treatment LP+M2. No significant difference was found in total serum protein (TP) and serum urea nitrogen (SUN) among all treatment groups (p > 0.05). Skin length of treatment HP and LP+M2 was higher than that of other groups (p < 0.05). Body length, skin weight, length of guard hair and under hair were not affected by different dietary protein levels (p>0.05). The best performance could be observed in treatment LP+M2. In diet, 24% (DM) protein level with 1.54% Met supplementing was enough for minks during growing-furring period. Dietary protein lowered from 32% to 24% with supplementing Met in diets would result in a 37.9% decrease in urinary N excretion. Furthermore, addition of Met in diets for minks would be beneficial in terms of reducing feed expenses and lessening nitrogen emissions to the environment.     

Effect of dried Gliricidia sepium leaf supplement on feed intake, digestibility and nitrogen retention in sheep fed dried KW4 elephant grass (Pennisetum purpureum) ad libitum

A feeding experiment was conducted to study the effects of supplementation with dried Gliricidia sepium leaves on dry matter (DM) intake, digestibility and nitrogen retention in sheep fed KW4 elephant grass. Four mature rams were fed elephant grass ad libitum supplemented with four levels of gliricidia leaves (0, 4, 8 and 12 g DM kg⁻¹ lwt day⁻¹) in a 4 × 4 Latin square design. Supplementation with gliricidia leaves decreased elephant grass DM intake (g DM day⁻¹ or g DM kg⁻¹ BW^0.75 day⁻¹). However, the effect of supplementation on total DM intake of the rations was not significant (P >; 0.05). Total crude protein intake significantly (P < 0.001) increased with increasing levels of gliricidia supplementation. Total DM digestibility and body weight changes were significantly (P < 0.05) improved by gliricidia supplementation; with the highest digestibility coefficient (60.5%) and body weight gain (89.3 g/day) obtained at 8 g DM kg⁻¹ lwt day⁻¹. Gliricidia supplementation significantly (P < 0.001) improved nitrogen intake, absorbed nitrogen and retained nitrogen but with no significant difference at 8 and 12 g DM kg⁻¹ lwt day⁻¹ level of supplementation. The highest efficiency of N retention by sheep (44.9%) was obtained at 8 g DM kg⁻¹ lwt day⁻¹ level of gliricidia supplementation. The results indicated that supplemention of KW4 elephant grass with small quantities of gliricidia leaves up to 8 g DM kg⁻¹ lwt day⁻¹ enhance utilisation efficiency of the total ration. Further increases in the level of gliricidia supplementation, under the conditions of this experiment, reduced the intake of elephant grass leading to substitution effects of the basal. This revised version was published online in August 2006 with corrections to the Cover Date.     

Intake and relative palatability indices of acacia species fed to sheep and goats

An experiment was conducted to determine preference intake and relative palatability indices of Acacia karroo, Acacia nilotica, Acacia tortilis, Acacia sieberiana and Acacia rhemniana in sheep and goats using a completely randomized design. The size of Experimental Farm from which the browses were harvested was 1842.75 ha. The leaf samples were randomly collected from various young trees. The samples were analysed for proximate composition, measured for intake and relative palatability indices of sheep and goats. Dry matter (DM) content ranged from 917.4 to 936.8 g/kg DM and organic matter from 822.9 to 892.2 g/kg DM. All acacia species contained crude protein content (CP) of more than 7–17% required for grazing animals. The content of neutral detergent fibre (ADF) and acid detergent fibre ranged from 372.8 to 658.1 and 150.0 to 464.6 g/kg DM, respectively and were significantly (P < 0.05) different among the species. All of the acacia species had low levels (0–5.57 g/kg DM) of condensed tannins. The intakes of all feeds except A. karroo and A. rhemniana were high in both sheep and goats. The leaves from A. sieberiana had the highest palatability indice (Pi) while those of A. rhemniana had the lowest Pi in both sheep and goats. It was concluded that there was an effect of acacia species on intake and relative palatability indices. Species A. sieberiana, A. nilotica and A. tortilis have potential as livestock fodder, based on moderate to high CP value, low ADF, low tannins, high intake and relative palatability indices.     

Influence of forbs and shrubs on intake,digestibility, and nitrogen and energy balance in sheep fed low-quality straw

A 4×4 Latin square experiment (Exp) was conducted using eight Debouillet yearling wethers with two wethers/cell to compare the effects of forbs and shrubs supplementation to a low-quality barley straw with alfalfa hay (ALF) supplementation in terms of nutrient digestion and balance. Diets studied in the Exp were barley straw (0.56% N) and straw plus either 42% ALF, 63% forbs (a 50:50 mixture of scarlet globemallow and leatherleaf croton) or 62% shrubs (mixture of 50% fourwing saltbush and 50% mountain mahogany). Diets containing ALF, forbs and shrubs were isonitrogenous (1.68% N). Periods of each Latin square were 15 days with total fecal and urine collections obtained on the last 5 days of each period. Dry matter intake of ALF and shrub-containing diets was similar and higher (P<0.05) than straw alone or straw plus forb diets. Nitrogen (N) retention was improved, but NDF digestibility was reduced (P<0.05), in diets containing ALF and shrubs compared with straw only. No difference in N retention among diets were detected (P>0.05) when N intake was used as a covariate. Metabolizable energy (ME) content of all the diets was similar except the shrub containing diet that was lower than the straw plus forbs or straw plus ALF but similar to the straw diet. Forbs had little influence on digestion and N utilization in the Exp presumably because of their reduced acceptability in the dried and ground form by sheep. Results suggest that native shrubs used in the study influenced intake and N utilization in a manner similar to ALF; and forbs used were similar in ME to ALF.     

Intake, rumen digestion, digestibility and microbial nitrogen supply in sheep fed Cynodon nlemfuensis supplemented with Gliricidia sepium

Four Pelibuey sheep fitted with flexible rumen cannula were fed increasing levels of Gliricidia sepium foliage (gliricidia) in a 4 × 4 Latin square design. Treatments were: control, 10, 20 and 30% (dry basis) of gliricidia mixed in a basal diet of Cynodon nlemfuensis (stargrass) hay. Dry matter (DM), organic matter (OM) and crude protein (CP) intakes were linearly increased (P < 0.05) from 45.2, 40.4, 2.0 to 71.5, 63.3 and 6.8 g/kg W^0.75/d, for the control and the 30% gliricidia diet, respectively. Similarly, increments of gliricidia in the diet resulted in a linear increase in DM, OM and CP apparent disgestibilities from 43.7, 48.4 and 27.0 to 50.7, 54.7 and 57.3%, for the control and 30% gliricidia diet, respectively. There was no effect (P > 0.05) of supplementation with gliricidia on rumen dry matter digestion of stargrass. Microbial nitrogen (N) supply to the small intestine had a trend towards an increase from 4.9, for the control, to 9.6 g N/d, for the 30% diet, though it was not significant (P > 0.05). It is concluded that, gliricidia might be incorporated into low quality diets since it increases total DM intake, supplies highly degradable N to the rumen and appears to increase the microbial N supply to the small intestine of sheep. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of diet inclusion of <Emphasis Type="Italic">Tithonia diversifolia</Emphasis> on feed intake,digestibility and nitrogen balance in tropical sheep

Feed intake and digestibility were evaluated in sheep fed low quality Taiwan grass supplemented with Tithonia diversifolia. Four wether hair sheep were housed in metabolic cages and fed with either Control concentrate 20%, Tithonia 20, 35 or 50% in a Latin Square design. Adaptation and, feces and urine collection periods were 14 and 7 days, respectively. Feed intake was increased (P < 0.01) from 58.5 in control to 86.1 g/kg^0.75 in sheep fed Tithonia. NDF intake and digestibility were affected by Tithonia level. Nitrogen intake increased linearly (P < 0.01) with increase in feces and urine excretion. N retention was similar (P > 0.1) among sheep fed Tithonia, but different (P < 0.05) from control. Inclusion of Tithonia foliage at 20% of the DM diet of hair sheep improved their intake of low quality Taiwan grass and nitrogen retention. Higher levels of Tithonia in the diet, however, increase nitrogen loss in feces and urine.     

Vernonia amygdalina as a supplement to teff straw (Eragrostis tef) fed to Ethiopian Menz sheep

Sixteen rumen fistulated Ethiopian Menz type sheep were used in a completely randomized block design (CRBD) in experiment 1. Unchopped teff straw was fed alone or supplemented with either 100, 150 or 200 g/d of sun-dried vernonia leaves. The chemical compositions of fresh, boiled, water-soaked and sun-dried vernonia and soluble carbohydrate (SC) loss by boiling were determined. In experiment 2,25 growing Ethiopian Menz type sheep, were fed teff straw alone or supplemented with 120 g (DM) of either boiled (B) or soaked (S) fresh vernonia with or without molasses (M) (50 g). SC lost by boiling fresh vernonia for 15, 30, 45 or 60 min was determined.In experiment 1, boiling increased the nitrogen (N) concentration in vernonia but sun-drying reduced it. N bound to fibre (NDF-N) was reduced by boiling but not by soaking. SC loss increased with boiling time. Supplementation did not affect the degradation constants (a, b, PD, c) of teff straw, but DM disappearance was increased (p<0.05) at 76 and 120 h of incubation. Intake of sun-dried vernonia was poor but increased with quantity offered. Intakes and digestibilities of DM, OM and the fibre fractions were marginally higher (p<0.05) in the supplemented diets. Nitrogen balance in the supplemented diets was low due to increased faecal and urinary excretion. In experiment 2, rumen NH₃–N was higher for the boiled treatments compared to the soaked treatments. Acceptability at both 2 and 4 h was highest for BM, followed by SM, B and S. Boiling for 30 min, but not soaking, enhanced the acceptability of vernonia, suggesting that a pretreatment may enhance the feed value of vernonia.     

Acacia angustissima: Its anti-nutrients constituents, toxicity and possible mechanisms to alleviate the toxicity – a short review

In most tropical countries poor nutrition limits ruminant productivity. The main feed resources include native pasture and crop residues, which are low in nitrogen (6.2-10.6 g/kg DM) and high in fibre (676-772 g/kg DM). Nutritional deficiencies of these feeds can be alleviated by supplementation with fodder trees such as Acacia angustissima, which are multipurpose, have outstanding agronomical attributes and are rich in nitrogen (33.2-40.8 g/kg DM). However, feeding A. angustissima without adaptation caused toxicity to sheep. Rats fed diets containing 20% A. angustissima died within 2-5 d. Intake and average daily gain (6.0 and 0.5 g/d) were significantly (P 0.05) reduced in rats fed a diet containing 70% acetone extract compared to the rats fed the control diet (8.8 and 3.1 g/d). Addition of polyethylene glycol (PEG) improved in-vitro gas and ammonia production from A. angustissima leaves (gas, 3.9 to 13.4 ml/100g DM; ammonia, 2.8 to 8.5 mM). PEG also increased DM intake (696 and 860 g /d) in sheep fed A. angustissima. These results suggested that tannin contributed to the negative effects of A. angustissima. Non-protein amino acids (4-N-acetyl-2, 4-diaminobutanoic acid, acetyl diaminopropionic acid, oxalyl diamino butyric, oxalyl diaminopropionic) have also been isolated from A. angustissima leaves. Feeding A. angustissima to sheep by gradually increasing levels in the diet prevented toxicity. Additionally, transfer of rumen contents from adapted to non-adapted sheep prevented toxicity of A. angustissima. These observations suggested that adaptation was at the microbial level. Current work to alleviate the toxicity of A. angustissima is therefore focused on microbial adaptation and detoxification. Tannin-tolerant bacteria have been isolated from sheep adapted to A. angustissima and free-ranging animals. Work on non-protein amino acids is underway. Overcoming the negative effects of the anti-nutritional factors in A. angustissima would not only improve livestock productivity but also result in improvement of the environment. This revised version was published online in June 2006 with corrections to the Cover Date.     

Stockpiled tall fescue and livestock performance in an early stage midwest silvopasture system

Using stockpiled forage can substantially reduce livestock feed costs over the winter. However, little is known about utilizing stockpiled forage in an early-stage silvopasture system. This study was conducted to determine if silvopasture production practices utilizing stockpiled forage influence stocker steer performance. The treatments were: (1) stockpiled forage in a non-forested pasture (OPEN) and (2) stockpiled forage in a silvopasture (TREE). Grazing began early December and ended in late February in each of 2 years. Each treatment was replicated three times in a completely randomized design. Forage nutritive value, production, and steer average daily gain (ADG) for the OPEN and TREE treatments were not significantly different as long as the areas occupied by trees was excluded from analyses. When the area occupied by trees was included, the OPEN treatment produced more (P < 0.01) forage than the TREE treatment, with the OPEN producing 3510 kg ha⁻¹ and the TREE producing 2812 kg ha⁻¹. Average daily gain (P = 0.21) was 0.41 kg for the steers in the OPEN treatment and 0.37 kg for steers in the TREE treatment. Gain per ha was significantly different (P < 0.01); the OPEN treatment produced 193 kg of animal gain and the TREE treatment produced 125 kg of animal gain. Exclusion of the area under the tree row from the analysis changed the total gain per ha for the TREE treatment to 148 kg, but was still less (P = 0.01) than the OPEN treatment.     

Potential impact of prickly pear cactus flour and <Emphasis Type="Italic">Salix babylonica</Emphasis> extract on cecal fermentation and methane production in horses

The cecal gas (GP) and methane (CH₄) production and cecal fermentation kinetics when corn grain (CG) was replaced with prickly cactus (PC) in a horse’s diet at different levels of Salix babylonica (SB) extract was investigated. Three total mixed rations where CG was replaced with PC at three levels (/kg): 0 g (Control), 75 g (PC75) or 150 g (PC150) were prepared and SB extract added at four levels: 0, 0.6, 1.2 and 1.8 mL/g dry matter (DM) of substrates. No ration type × SB extract dose interaction was observed (P > 0.05) for GP kinetics and CH₄ production. Increasing the level of PC in the ration quadratically increased (P < 0.01) the asymptotic GP and decreased (P < 0.01) the rate and lag time of GP. Increasing the level of PC in the ration, increased GP values (P < 0.05). Increasing the level of SB extract linearly decreased (P = 0.001) the lag time of GP of all diets without affecting the asymptotic GP or the rate of GP. Ration type and SB level had no effect (P > 0.05) on CH₄ production; however, at 36 h of incubation, SB extract decreased CH₄ production. The rations PC75 and PC150 increased cecal pH compared with the control ration. The PC150 ration had the highest (P < 0.05) DM degradability, short chain fatty acids production, and gas yield after 24 h of incubation, with no effect (P > 0.05) of SB inclusion on all investigated fermentation kinetic parameters. It is concluded that increasing the level of PC in the diet of horse and replacing CG up to 60%, increased GP and improved cecal fermentation kinetics without affecting CH₄ production. Inclusion of S. babylonica extract in the tested rations had weak effects on fermentation kinetics although it decreased the lag time of GP.     

In vivo digestibility and nitrogen balance in sheep diets with foliage of fodder trees in substitution for soybean meal

Apparent digestibility and nitrogen (N) balance were evaluated in sheep fed low-quality Cynodon nlemfuensis grass supplemented with different foliages of forage-potential trees. Four male hair sheep were housed in metabolic cages and fed in a Latin Square design with 30 % inclusion of foliage of Erythrina indica (Ei), Moringa oleifera (Mo), or Trichanthera gigantea (Tg) replacing soybean meal. Adaptation and faeces and urine collection periods were 14 and 7 days, respectively. Sheep received 70 g DM/kg/BW^0.75 of the diet in order to achieve total consumption of feed. Dry matter, organic matter, and neutral detergent fiber digestibilities were similar (P > 0.05) among the control, Mo, and Ei diets, while the Tg diet resulted in the lowest (P < 0.05) value. The Ei diet showed the highest (P < 0.05) total N intake among the three diets with 30 % of leaf meal, which was similar (P > 0.05) to the control diet. N excreted in faeces was highest (P < 0.05) in the Tg diet when compared to the other leaf meal diets, in which the Mo diet presented the lowest (P < 0.05) value, but was similar (P > 0.05) to that found in the control diet. The Mo and Ei diets had similar (P > 0.05) values for the percent of N absorbed by the animals, which was much higher (P < 0.05) than that of the Tg diet. The forage of M. oleifera and Ei can be used in diets at 30 % incorporation to substitute the use of soybean meal in small ruminant production.     

Promoting intake of Cratylia argentea as a dry season supplement for cattle grazing Hyparrhenia rufa in the subhumid tropics

Cratylia argentea, a drought tolerant shrub, is known to produce significant amounts of fodder during the dry season but little is known of its nutritive value for feeding animals. Two studies of quality and intake of Cratylia argentea, as an arboreal protein supplement for crossbred dual purpose cattle grazing Hyparrenhia rufa in the dry season, were carried out in San Miguel de Barranca, Puntarenas, Costa Rica (January–May). The first experiment was a 2 × 2 factorial arrangement of two forms of C. argentea foliage presentation: 1) fresh or wilted; and 2) sprayed or not with sugarcane molasses diluted in water. Wilting did not affect crude protein content and in vitro dry matter digestibility (IVDMD) but treating fresh C. argentea with molasses increased IVDMD by from 55.6 to 60.8% (P < 0.01). Intake of fresh C. argentea increased by 32% with wilting and by 43% with molasses treatment. Pooling data across treatments, a quadratic relationship between dry matter intake of H. rufa (y) and the amount of N consumed in C. argentea (x) was found (y = 1.25 + 0.095x – 0.001x ²). In the second experiment, milk production from the following treatments was evaluated: 1) chicken litter and molasses (D₁); 2) chicken litter, sugar cane and wheat bran (D₂); and 3) C. argentea, sugar cane and wheat bran (D₃). Milk yields averaged 6.0 kg cow^–1 day^–1 and there were no significant differences between treatments. Milk fat was lower for D₂ (2.7%), which had a higher amount of sugar cane in the diet, but differences were not significant. On the other hand, non-fat solids and lactose concentration of milk was higher (P < 0.05) for D₂. Wilting or molasses treatment were effective management strategies for increasing dry matter intake of C. argentea. A higher dry matter intake of C. argentea was associated with increased intake of the fibrous H. rufa grass. Diets with C. argentea as the main protein source gave similar milk production levels and quality to those with chicken litter.     

Effects of fitch odor (Mustila eversmanni) on behavior and breeding of root voles (Microtus oeconomus)

From April to December in 1997 at Northwest Plateau Institute of Biology, Chinese Academy of Science, the effect of predation risk on social behavior, feeding, reproduction and sexual hormones of the root voles (Microtus oeconomus) was studied when the root voles (Microtus oeconomus) were exposed to the odor of fitch (Mustila eversmanni). The results showed that the root voles delayed breeding period and the frequency of the copulation significantly lowered (P<0.01). Comparing with the control group, the accumulated time of amicable behavior in females, and general activity of both sexes increased significantly (P<0.01). The frequencies of general activity (P<0.01), investigating activity (females:P<0.05, males:P<0.01), and self-grooming (P<0.01) of both sexes were less significantly. At the same time, the amount of energy intake (P<0.05) and body weight (P<0.01) of the root voles decreased significantly. The litter weight and ovary index of females decreased (P<0.01). For males the sperm count in epididymides also decreased significantly (P<0.01). The progesterone in the blood serum of root voles females increased significantly under fitch odor (P<0.01). Biography: WANG Zhen-long (1971-), male, lecture in Department of Biology, Qufu Normal University, Qufu 273165, P.R. China Responsible editor: Zhu Hong