J.H. Topps

Nutrient intake and utilisation by goats fed dried leaves of the shrub legumes Acacia angustissima, Calliandra calothyrsus and Leucaena leucocephala as supplements to native pasture hay

Thirty-six indigenous goats were used to determine the potential of sun-dried leaves of the shrub legumes Acacia angustissima, Calliandra calothyrsus and Leucaena leucocephala as supplements to native pasture hay (NPH). The dried leaves were included at the rates of 80, 160 and 320 g/head/ day. Cottonseed meal fed at the same levels, and NPH fed alone were included as controls. Among the browses, C. calothyrsus had the lowest N content of 19.0 g/kg dry matter (DM) and A. angustissima the highest of 35.0 g/kg DM. The leaves from the legumes had significantly less N and higher cell wall, neutral detergent insoluble N (NDIN) and acid detergent insoluble N (ADIN) contents than cottonseed meal. The values of NDIN as a fraction of total N were 19, 456, 526 and 816 g/kg for cottonseed meal, L. leucocephala, A. angustissima and C. calothyrsus, respectively. Proanthocyanidin contents were 33, 196 and 134 g/kg DM for A. angustissima, C. calothyrsus and L. leucocephala, respectively. Type of supplement did not affect (P > 0.05) NPH, total and digestible DM intakes although NPH intake was depressed (P < 0.05) at the highest level of supplementation compared to the first two levels. Animals fed legumes excreted significantly more (P < 0.001) faecal N (g/kg N intake) than animals consuming cottonseed meal. The reverse was observed for urine N. Among the legumes, C. calothyrsus had significantly higher (P < 0.001) N in faeces (958 g/kg N intake) than A. angustissima (630) and L. leucocephala (615). Significant (P < 0.05) correlation coefficients were obtained between proanthocyanidins (PAs) intake and faecal N, NDIN and ADIN (0.535, 0.501 and 0.786, respectively). Regressing digestible N on N intake indicated that A. angustissima and C. calothyrsus tannins had significant effects on the digestion of dietary N. The animal responses were discussed in relation to PAs content. It was concluded that both the type and level of PAs were important determinants of the animal responses.

Nutritional and anti-nutritional characters and rumen degradability of dry matter and nitrogen for some multipurpose tree species with potential for agroforestry in Zimbabwe

Abstract In a preliminary study on the nutritional value of seven multipurpose trees (MPTs), currently showing potential use in agroforestry systems in Zimbabwe, crude protein values ranged from 189 g kg −1 DM in Flemingia macrophylla to 292 g kg −1 DM in Acacia angustissima . Acid detergent fibre (ADF) content was low especially in Sesbania sesban (99 g kg −1 DM), while ADF contents in Flemingia macrophylla (277 g kg −1 DM) and Cajanus cajan (255 g kg −1 DM) were the highest. The MPTs had ash contents ranging from 58 g kg −1 DM in Flemingia macrophylla and Cajanus cajan to 95 g kg −1 DM in Sesbania sesban . MPTs with detectable amounts of condensed tannins were Calliandra calothyrsus (17.9 g kg −1 DM), A. angustissima (10.3 g kg −1 DM) and Flemingia macrophylla (3.4 g kg −1 DM). These MPTs were poorly degraded in the rumen compared to the other four species. The presence of condensed tannins could lower their potential as ruminant feeds.

Effects of supplementation with foliage from the tree legumes Acacia angustissima, Cajanus cajan, Calliandra calothyrsus and Leucaena leucocephala on feed intake, digestibility and nitrogen metabolism of sheep given maize stover ad libitum

Foliage (leaves, small-diameter stems and flowers and fruits if present) was harvested in March 1994 from Acacia angustissima, Cajanus cajan, Calliandra calothyrsus and Leucaena leucocephala and given as a supplement at four levels (0, 50, 100 and 150 g dry matter/day) to a diet of maize stover fed ad libitum to sheep. Sixteen sheep were used and divided into four groups of four, each with a mean weight of 18 kg. Each group was allocated at random to one of the legumes. Four 4 × 4 Latin square design experiments were carried out using 14-day periods and during the second week of each period feed intake, digestibility, nitrogen balance and microbial protein yield were measured. For each legume, other than C. calothyrsus, there was a significant increase (P < 0.05) in dry matter intake as the level of supplement increased. For all four legumes, there was a significant increase (P < 0.05) in digestibility of organic matter, nitrogen balance (NB) and microbial protein yield as the level of supplement increased. As judged by increases in intake of digestible organic matter and NB, A. angustissima gave the best response, followed by C. calothyrsus and L. leucocephala which were similar and then C. cajan gave the poorest response.

The effect of level of inclusion of the legume Desmodium uncinatum and the use of molasses or ground maize as additives on the chemical composition of grass- and maize-legume silages

The effect of the inclusion rate of legume and use of molasses or ground maize as additives on the chemical composition of grass- and maize-legume silages was investigated in two experiments. In experiment 1 the effects of adding molasses or ground maize to star grass (Cynodon nlemfluensis) with or without legume (Desmodium uncinatum) at ensiling were studied. Four additive treatments (no additive, molasses, 50 and 100 g ground maize/kg fresh weight) were combined with four levels of legume (no legume, 150, 300 and 450 g/kg fresh weight) in a factorial arrangement of treatments. Sealed plastic bags containing about 15 kg of compressed material were used and each treatment was replicated three times. In experiment 2 the effect of adding graded levels of legume (D. uncinatum) to maize (Zea mays) at ensiling was studied in a completely randomised block design. Four levels of legume were used at ensiling: no legume, 150, 300 and 450 g/kg fresh weight. The same procedure as that used in experiment 1 was applied. All the grass silages were well fermented. Addition of ground maize and molasses increased the dry matter content of grass silage (P < 0.001). Molasses addition resulted in lower (P < 0.05) levels of volatile nitrogen and higher (P < 0.05) lactic acid content compared to the control and the ground maize treatments. The inclusion of legume above 300 g/kg fresh weight raised the pH, volatile nitrogen and total nitrogen content of grass silages (P < 0.001). The increase in pH and volatile nitrogen content was less when the silages were treated with additive, especially molasses. All the maize silages were well fermented, with low pH and volatile nitrogen levels. Crude protein level was increased from 60 to 90 g/kg dry matter in the silage with no legume and at the highest level of legume (450 g/kg) respectively. The pH increased from 3.7 in silages with no legume to 4.2 when legume was added at the rate of 450 g/kg. The inclusion of D. uncinatum improved the quality of both grass and maize silages. However, the inclusion of legume above 300 g/kg fresh weight of grass silage would require the use of additives.

Effect of supplementing veld hay with tropical legumes Desmodium uncinatum, Stylosanthes guianensis and Macroptilium atropurpureum on intake, digestibility, outflow rates, nitrogen retention and live weight gain in lambs

In 2 consecutive years using fresh batches of lambs, poor-quality veld (natural pasture) hay dominated by Hyparrhenia grasses (23 g crude protein per kg dry matter) was fed ad libitum either alone or with one of three herbaceous tropical legumes at the rate of 0.25 of total feed consumed. The legumes Desmodium uncinatum (Silverleaf desmodium), Stylosanthes guianensis (Oxley fine-stem stylo) and Macroptilium atropurpureum (Siratro) contained 143, 114 and 159 g crude protein per kg dry matter, respectively, and, to varying degrees, increased feed intake, digestibility, energy intake and nitrogen retention and reduced live weight loss (P 0.05). Average daily consumption of total dry matter was 465 g in animals given veld hay alone compared with 636, 681 and 754 g in those supplemented with D. uncinatum, S. guianensis and M. atropurpureum, respectively. The daily intake of the basal veld hay was significantly increased (P < 0.05) by M. atropurpureum (574 g) but not by S. guianensis (514 g) and D. uncinatum (480 g). Average apparent digestibility coefficients of organic matter were 0.394, 0.440, 0.466 and 0.464 with veld hay alone, veld hay/D. uncinatum, veld hay/S. guianensis and veld hay/M. atropurpureum, respectively. Proportions of metabolisable energy intake relative to that required for maintenance were 0.61, 0.96, 1.11 and 1.20 in animals given veld hay alone and with D. uncinatum, S. guianensis and M. atropurpureum, respectively. Average calculated microbial nitrogen production was 3.46, 5.33, 6.07 and 6.58 g per day, respectively, in animals given veld hay alone and with D. uncinatum, S. guianensis and M. atropurpureum. Respective values for nitrogen retention and live weight gain were −1.44, 0.29, 0.70 and 1.06 g per day, and −98, −32, 0 and −8 g per day. Relative to nitrogen consumed per day, animals given D. uncinatum tended to excrete more nitrogen in their faeces (0.83) than those given S. guianensis and M. atropurpureum (0.71) probably due to a higher content of acid detergent insoluble nitrogen in D. uncinatum (608 g per kg total nitrogen) than in the other legumes (273 to 285 g per kg total nitrogen). Overall, M. atropurpureum appeared to be the best legume supplement for veld hay, followed by S. guianensis.

Chemical composition and dry matter degradability profiles of forage legumes Cassia rotundifolia cv. Wynn, Lablab purpureus cv. Highworth and Macroptilium atropurpureum cv. Siratro at 8 weeks of growth (pre-anthesis)

Abstract Three forage legumes were harvested at 8 weeks of growth before flowering (pre-anthesis) and analysed for their chemical constituencies after either sun- (4 days) or over-drying (60°C for 48 h). An experiment was conducted with three rumen fistulated Friesian steers (440 ± 20 kg live mass) to estimate the rumen degradability characteristics of dry matter in the dried forage legumes using the nylon bag technique. The chemical composition of the legumes showed substantial variations. Crude protein (CP) content varied from 225 to 282 g/kg DM while neutral detergent fibre (NDF) ranged from 328 to 425 g/kg DM. The acid detergent fibre (ADF) ranged from 282 to 326 g/kg DM. There were no significant differences in acid detergent lignin (ADL), calcium (Ca) and phosphorus (P) content of the legumes. The drying method had a significant effect on crude protein, neutral detergent fibre, acid detergent fibre and ash content. The degradation constant b varied significantly from 363 to 431 g/kg DM while there were no significant differences in the degradation constants a and c . The potential degradable fraction, a + b , was highest for lablab, 842, followed by cassia, 779, and siratro, 746 g/kg DM. At a passage rate of 2% per hour, the calculated dry matter degradability differed significantly between 669 and 716 g/kg DM. At higher passage rates of 5 and 8% per hour the effective degradability of the forage legumes did not differ significantly. The drying method had no effect on the degradability of dry matter. These results suggest that the three forage legumes at pre-anthesis stage of growth have a high protein content which is highly degradable in the rumen to an extent which may meet the microbial protein requirements for efficient use of low quality roughages. However, their ability to provide nutrients to post-ruminal sites still needs to be assessed.

The use of groundnut hay as a supplement for sheep consuming poor quality natural pasture hay

Abstract A 5 × 5 latin square design experiment using five male sheep (60–70 kg live weight) was carried out to assess the effects of supplementing poor quality veld hay with groundnut hay on intake, digestibility, rumen environment and digesta kinetics. Five diets were formulated in which veld hay with 1% urea was fed alone (Control) or together with 100 g, 200 g or 300 g groundnut hay (100Gnut, 200Gnut or 300Gnut, respectively) and groundnut hay fed alone (Gnut). The forages were coarsely chopped prior to feeding. The groundnut hay supplements increased total feed intake and in vivo digestibility of the diets ( P

Chemical composition and degradability of Brachystegia spiciformis (musasa) leaves and stems harvested over 4 months from three sites in Zimbabwe

Brachystegia spiciformis terminal shoots (leaf and young stems) samples were harvested from September to December 1994 at Grasslands and Henderson Research Stations and Gwebi College of Agriculture. The samples were analyzed for crude protein (CP), ash, phosphorus, neutral detergent fibre (NDF) and acid detergent fibre (ADF) content. Four rumen cannulated steers were used to determine degradability profiles of dry matter and nitrogen using the nylon bag technique. Significant differences (P < 0.05) between sites and month of sampling for CP, ash and phosphorus, NDF and ADF were found. The CP content of the samples ranged from 82 to 120 g/kg DM. Lower CP levels were found in stems as compared to the leaf. Ash content ranged from 30 to 45 g/kg DM with samples from Grasslands significantly (P < 0.05) lower than those from the other two sites. The phosphorus levels were strongly affected (P < 0.05) by both the site and month of sampling and declined with time. The phosphorus values ranged from 1.23 to 2.67 g/kg DM. The stems were more fibrous than the leaves. From the exponential equation used in the degradability studies the soluble fraction (a) in the dry matter ranged from 17.6 to 29.9 and there were significant differences (P < 0.05) between both site and month of sampling. The potentially degradable fraction (b) in the DM was not affected by either site or month. The effective degradability at passage rates of 0.02, 0.05 and 0.08 passage rates were significantly affected (P < 0.05) by both the site and month of sampling. The degradability values at 0.02 passage rate were low, ranging from 33.5 to 56.2 and also showed a decline from October to December.

Napier or groundnut hay as supplements in diets of sheep consuming poor quality natural pasture hay 1. Effect on intake and digestibility

Abstract Three experiments, each of a 5 × 5 Latin square design, were carried out using sheep to assess the effect of supplementing poor quality natural pasture (veld) hay with graded levels of napier or groundnut hay on intake and digestibility. In Expt 1, napier hay was fed at 0, 100, 200, 300 g/day or ad libitum. In Expt 2 the same levels of feeding were used with groundnut hay, while in Expt 3 napier and groundnut hay were each fed at 0, 150 or 300 g/day to enable a direct comparison of the two supplemental forages. All the forages used were chopped to a particle size of about 1 cm prior to feeding. The veld hay was supplemented with 1 percent urea and was always offered ad libitum. The forage supplements were fed separately. In all the experiments, the forage supplements increased total feed intake (P

Feeding napier hay as supplement to sheep given poor quality natural pasture hay: effects of level of napier hay supplement and inclusion of urea in the basal diet on intake and digestibility

Three experiments were carried out using lambs to assess the effect of level of napier hay and urea supplements on the utilization of poor quality natural pasture (veld) hay. In all the experiments the lambs were given graded levels of napier hay as supplements to the basal diet of veld hay. In Experiment 1, the veld hay was not supplemented with urea; in Experiment 2, the veld hay was supplemented with 1% urea while in Experiment 3, the veld hay was supplemented with 1% or 2% urea. In all the experiments napier hay supplements increased total feed intake and in vivo digestibility of the diet (P < 0.05). High levels of napier supplementation tended to reduce the intake of veld hay below the level achieved on the unsupplemented control diet. However this decrease in veld hay intake was not as much as anticipated had the napier hay (corrected for its digestibility) simply replaced veld hay. Increasing the level of urea from 1 to 2% did not increase feed intake or digestibility or alter the pattern of substitution of veld hay by the napier. Across treatments, there was some evidence that the gain in the intake of veld hay resulting from napier supplementation was greater when urea was not added to the veld hay. In all the experiments, the increase in food intake was associated with an increase in faecal dry matter excretion suggesting that the increase in feed intake was facilitated by an increase in digesta passage rate. These results confirm that forage supplements are effective in increasing the utilization of poor quality forages and the response to the napier supplements was not entirely due to increasing nitrogen intake.