Please read the abstract in the section 00front of this document / Dissertation (MSc Agric (Animal Nutrition))--University of Pretoria, 2006. / Animal and Wildlife Sciences / unrestricted

Two indoor feeding experiments were conducted at the Animal Physiology Unit (APU) of Massey University, involving young sheep, to investigate the effect of feeding forage willow upon the death of established parasites and upon parasite fecundity, using chaffed lucerne as the control diet. Experiment 1: Twenty-four (24) parasite-free weaned hoggets weighing 29.9 ±1.2 kg (SD) were individually penned and fed chaffed lucerne ad libitum during a preexperimental adaption period of 5 weeks. They were then fed either lucerne chaff or chopped willow for a further 5 weeks (n = 12/group) and intakes were adjusted such that the DMI of the two groups was similar during weeks 9 & 10. All lambs were infected with L3 larvae parasites comprising 20,650 Teladorsagia, 1,320 Trichostrongylus and 330 Cooperia through oral drenching 12 days before willow feeding started. This was done after confirmation that the sheep were free of nematodes through FEC analysis. Total faeces were collected for 3 day periods towards the end of weeks 9 & 10, to measure diet digestibility and total faecal egg excretion. The sheep were slaughtered at the end of week 10. Voluntary feed intake (VFI), FEC and liveweight were measured weekly, whilst burdens of individual parasites and carcass characteristics were measured after slaughter. Duplicate samples of each feed offered and individual animal refusals were taken daily and pooled weekly per animal for chemical analysis. Female worm fecundity was calculated by two methods. Blood samples for immunological analysis were collected on days 20, 34, 51 and 70, and analysed for components of white blood cells (WBC) and for lymphocyte subsets. Experiment 2: A 2 x 2 changeover experiment was conducted, involving two time periods (Period 1 and Period 2 each of 14 days) with the same diets as used in Experiment 1, fed to 9 individually penned parasite-free young sheep randomly allocated to experimental diets. The parameters investigated were FEC and larvae hatching. Initially, a period of 7 days was allowed for acclimatisation in which both groups were fed on half willow and half lucerne chaff. This was followed by Period 1 with 4 lambs fed lucerne and 5 fed willow, after which the diets were changed over for Period 2. Total faeces produced were collected from all animals on the last day of each period using bagged sheep. A known number of Teladorsagia eggs (500 epg) was then added to faecal samples from these sheep and faeces-egg mixtures were made from which FEC was determined, to see if egg recovery was affected by these diets. Faecal samples for Period 2 with added eggs were also incubated for 10 days to measure hatchability. The recovery of added Teladorsagia eggs in Experiment 2 was 85% in lucerne-fed lambs and 53% willow-fed lambs (P<0.001); these were used as correction factors for Experiment 1 data. Larvae that hatched per gram of wet faeces in Experiment 2 tended to be lower for sheep fed willow than lucerne chaff (71% vs 83% of eggs added; P=0.08). Willow feed offered had lower DM (P<0.001) and CP (P<0.05) content, but had a significantly higher OM content (P<0.01) than lucerne chaff. Condensed tannin content of chopped willow was 27 g/kg DM, with only traces for lucerne. Apparent digestibility for DM (62.4% vs 59.5%; P≤0.05), OM (64.8% vs 59.9%; P≤0.001), DOMD (58.1% vs 55.0%; P≤0.01) and calculated ME (9.48 MJ/kg vs 8.96 MJ/kg; P≤0.01) were higher for the willow diet. VFI was similar for both groups during the adaption period (P>0.05) but declined with the introduction of willow in week 6 (P<0.001) and then progressively increased until it was similar to lucerne-fed sheep in weeks 9 & 10 (P>0.05). Calculated DM intake per head/day during the last two weeks of Experiment 1 was similar for the two groups (P>0.05); while the willow group had higher ME (P<0.01) and CP (P<0.001) intake per animal/day. Liveweight increased for the two groups during the adaption period (P>0.05), then declined for willow-fed lambs in week 6 (P<0.001) but later increased and by week 10 was similar to that of lucerne-fed lambs. The willow-fed lambs had lower carcass GR than the lucerne-fed lambs (P<0.01) when carcass weight was used as a covariate. Adjusted total daily egg production in Experiment 1 was lower in willow-fed sheep than lucerne-fed sheep, due to reductions for Haemonchus spp. (P<0.05) and Teladorsagia spp. (P<0.05). The per capita fecundity for Haemonchus worm spp. (P<0.05) and the in utero fecundity in both abomasal Teladorsagia spp. and small intestinal Trichostrongylus spp. (P<0.001) were lower for willow-fed sheep. There was reduced production of larvae for both Haemonchus spp. and Teladorsagia spp. (P<0.05) in willow-fed sheep. Feeding willow reduced the burden of Haemonchus adult worms in the abomasum (P<0.01) but reduced female worm burden only in Teladorsagia spp. (P<0.05) and reduced Cooperia spp. in the small intestines (P<0.01). Total WBC, total lymphocytes, subsets of lymphocytes and other white-cell groups were not affected by willow feeding (P>0.1). It was concluded that feeding chopped willow to young sheep reduced nematode worm burdens in the abomasum, especially both male and female Haemonchus spp., and reduced female worm burdens of Teladorsagia spp. Female worm fecundity of both species was also reduced by willow feeding. These reductions have been associated with CT content in the willow feed and the reduced worm burdens have been attributed to the death of the established worms by CT, since there was no evidence of immune priming in willow-fed sheep. Compounds present in the faeces of willow-fed sheep have been found to mask some of the nematode eggs, making them invisible by microscopic examination while keeping their viability. It is postulated that this could be due to binding of nematode eggs to insoluble CT associated with indigestible fibre in the faeces of willow-fed sheep. Conventional methods of measuring FEC therefore underestimated nematode eggs present in the faeces of willow-fed sheep and this needs to be checked for other CT-containing forages.

A series of grazing experiments were conducted in the summer/autumn of 2003 and 2004 at Massey University's Riverside dryland farm near Masterton in Wairarapa on the East Coast of NZ, to study the effects of grazing willow fodder blocks (6,000 stems/ha) upon the production and reproductive performance of ewes relative to ewes grazing drought pastures. Drought pastures were simulated in this study and included short drought pasture and long drought pasture. Pasture with a low pre-grazing mass of approximately 1500 kg OM/ha, a dead matter content of >50 % and a sward height of 5-7 cm was defined as short drought pasture typical of drought conditions. Long drought pasture was similar to pasture growing in the willow fodder blocks, with a pre-grazing pasture mass of >4000 kg OM/ha, a sward height of > 30cm and a dead matter content of 30-60 % . Willow fodder blocks were established on low-lying wet, marshy areas of the farm that had very low or zero productivity in the undeveloped state. Pasture development in the fodder blocks was noticed with the growth of unsown grasses and legumes, as the areas dried up following the planting of willow stakes, due to evapotranspiration from the trees. Forage in the willow fodder blocks included both trees and pasture that was grown under the trees. The nutritive value of short drought pasture was low with an ME of 8 MJ/kg O M ; long drought pasture ranged between 8- 1 0 MJ ME/kg DM; willow pasture contained 8 MJ M Elkg DM in 2003 and 1 0 MJ ME/kg OM in 2004. The nutritive value of edible willow tree (<5 mm diameter) was superior to drought pasture with an ME of > 10 MJ/kg OM. The concentrations of the secondary compounds such as condensed tannins (CT ; 30- 40 glkg OM) and phenolicglycosides ( PG ; 1 5-35 g/kg DM) were higher in willow trees compared to their concentrations (CT ; 2-3 g/kg DM) and (PG; 2-9 g/kg OM) in control drought pastures. Experiments involving short drought pasture, long drought pasture and willow fodder blocks as treatment groups were grazed by ewes for 10 weeks in regular breaks from mid February to early May. Ewes were mated during this period and were joined together after mating and grazed on normal pasture until weaning. Live weight (LW) change and body condition score (BCS) were recorded throughout the experiments, whilst reproductive performance of ewes was measured as the number of lambs recorded at ultrasound pregnancy scanning, lambing, docking and weaning. Measurements on wool production were also recorded at weaning. In 2003, experimental ewes grazed control drought pastures (short and long) and willow fodder blocks (restricted and full access) as treatment groups (n= 1 00 ewes/group; Chapter 2). Ewes grazing short drought pasture had an allowance of 0.8 k g DM/ewe/d whilst ewes with restricted access had an allowance of 0.8 kg DM/ewe/d from drought pasture and 0 .4 kg OM/ewe/d from willow fodder blocks. Ewes in full access treatment group had no access to pasture but were confined to willow fodder blocks at an allowance of 2.0 kg OM/ewe/d, which was the same allowance given to long drought pasture ewes. Ewes grazing short drought pasture lost weight at approximately 1 00g/d and recorded a low reproductive rate (90 lambs weaned/100 ewes mated) with a high proportion of single lamb births. Live weight loss was significantly reduced to 40 g/d in ewes grazing willow fodder blocks (full access) with a 20% units increase in reproductive rate due to more multiple births (P <0. 05). Ewes grazing long drought pasture performed intermediate to ewes with full access to fodder blocks and ewes grazing short drought pasture, whilst ewes with restricted access performed similar to ewes grazing short drought pasture. In 2004 (Chapter 3), the restricted access to willow fodder blocks treatment was eliminated from the study and the number of ewes was increased to 165 ewes per treatment group. Performance of ewes grazing short drought pasture was similar to that of ewes grazing short drought pasture in 2003 , with ewes loosing live weight (40g/d) and a low reproductive rate (90 lambs weaned/l00 ewes mated) whilst ewes grazing long drought pasture gained L W (54 g/d) and had a higher reproductive rate (P<0.05). Ewes grazing willow fodder blocks performed better than ewes grazing short drought pasture by maintaining L W and their reproductive rate was intermediate to ewes grazing short and long drought pasture. In 2005, a short grazing trial with rumen fistulated sheep was conducted to study the effect of supplementing willow to ewes grazing drought pastures upon plasma amino acid concentrations (Chapter 4) and upon the microbiology of the rumen (Chapter 5 and 6). Grazing occurred during summer/autumn for 10 weeks with two treatment groups; control (short drought pasture; n=7) at an allowance of 0.8 kg DM/ewe/d and ewes grazing short drought pasture at 0.8 kg DM/ewe/d plus a supplement of fresh willow at 1.4 kg fresh willow/ewe/d (n=7) . Blood samples for the quantification of plasma amino acids were collected at week 5 and 10, with L W and BCS measured at fortnightly intervals. Short drought pasture in this experiment had a low pasture mass (2000 k g DM/ha) and a low nutritive value (8 MJ/kg DM), whilst willow had a higher M E of 10 MJ/kg OM. Both groups of ewes lost live weight at the rate of 50 g/d. Plasma concentration of 3 methylhistidine (3-MTH; 88 vs 127μ mole/L) at week 5 and non essential amino acids (NEAA; 1082 vs 1417μ mo1e/L) at week 5 and ( 1155 vs 1324 μ mole/L) at week 10, were substantially lower (P<0 .05) in w illow supplemented ewes than control ewes. It was concluded that the increased reproductive rate from willow supplementation in ewes grazing drought pasture might be partly explained by reduced body protein catabolism, besides also increasing plasma branched chain amino acids CBCAA) and essential amino acids (EAA) concentrations. To investigate the effects of willow supplementation on rumen microbes, rumen samples were collected during the 2005 experiment with fistulated ewes over a 10 week period. The study involved the use of a molecular technique ( Chapter 5), denaturing gradient gel electrophoresis (DGGE), to compare the rumen microbial populations between the control and supplemented ewes and a cultivation technique (Chapter 6) to study the effect on rumen bacteria of ewes grazing drought pastures with and with out willow supplementation. DGGE analysis of the V3 region of 16S ribosomal RNA genes in DNA extracted from samples of rumen contents taken fortnightly over a 10 week feeding period showed a distinct difference in banding patterns between treatment groups which progressively developed over time, showing rumen microbial adaptation to willow supplementation. However, phylogenetic analysis of the DNA sequences retrieved from the DGGE bands from willow-supplemented and control ewes did not cluster by treatment group. It was deduced that willow supplementation induced a change in rumen bacterial populations through selecting sub-populations of organisms already present in the rumen. The changes in the rumen bacterial populations is attributed to the ability of these bacteria to metabolise secondary compounds in willow such as phenolicglycosides and flavanoid monomers and their ability to resist the inhibitory effects of condensed tannins. The cultivation study involved enumeration, isolation and purification of bacterial colonies on Complete Carbohydrate, Salicin, Xylan, Cellulose and Willow media followed by full characterisation of a representative set of pure bacterial cultures. Total bacterial counts on the above media at week 5 and week 10 were generally lower in willow-supplemented ewes compared to control ewes and the 16S rRNA gene sequences of the majority of iso lates characterised from both Salicin and Xylan media, were most closely related to species from the Pseudobutyrivibrio genus. Isolates from Willow medium clustered as two distinct groups. One group (mostly isolated from control ewes) was made up of mainly of organisms not usually associated with the rumen and probably represent non-resident organisms that are passing through the rumen. The other group of bacteria were mainly retrieved from willow-supplemented ewes and were most closely related to species of the Ofsenella genus. Compared to bacteria isolated on Salicin and Xylan media, isolates on Willow medium showed little ability to ferment various carbohydrates or trypticase (hydrolysed protein) but were able to utilise secondary compounds from willow. It was concluded that willow fodder blocks are useful sources of supplementary fodder for mating ewes during drought situations. Both the field and m icrobiological studies showed adaptation to the willow supplementary diet, including the detection of Olsenelfa-like bacteria for the first time in the rumen. It is suggested that the principal purpose of the rumen investigation is the degradation of secondary compounds present in willow.

This PhD thesis consists of nine chapters describing aspects of the subsistence farms of western Nepal in general, and a need-based evaluation of multipurpose fodder trees (MFT) as a source of dry-season forage for ruminants in particular, as a basis for mitigating the current high rate of land degradation and loss of productivity in livestock production systems in the region. Understanding the complex farming systems that provide a living for 65% of the 27.1 million people in Nepal is the key to designing effective programmes of research and development. Evaluation methods include review of past work, farmers group workshops to identify current practice in the use of MFT in Nepal, studies on biomass production of Artocarpus lakoocha and Ficus glaberrima trees older than 50 years in Nepal and the propagation of F. benjamina, comparison of the feeding preferences of sheep for alternative browse species, and study of the nutritive value of alternative forage diets for lactating buffalo. Reviews showed 2.2 million cattle and 1 million buffalo are an extra burden to steep land where productivity is declining at the rate of 1.25% per year. Indigenous knowledge identified Ficus glaberrima with its three varieties (Maghe, Chaite and Jethe), A. lakoocha, F. benjamina and Bassia butyracea as the best four MFT for renovating degraded lands. A survey study showed significantly higher dry matter (DM) production by F. glaberrima than A. lakoocha (154 vs 91 kg DM /tree/year) during dry periods at low altitude (800 - 1000m). There was no significant difference in production of fat - corrected milk (FCM ) between buffalos eating A. lakoocha, F.glaberrima or a diet of 53% straw and 47% F. glaberrima (DM basis). Metabolisable energy balance (MJME/day) was greater in Artocarpus than Ficus, with the mixed diet intermediate (+1.60, -0.34 and -12.94 MJ ME/buffalo/day respectively, relative to requirements, P=0.0318). When fed together in an indoor trial, poplar (48% = 106 g DM/sheep/day) and willow (43% = 95 g DM/sheep/day) were preferred to Ficus benjamina (8% = 18 g DM/sheep/day) by sheep, reflecting the greater maturity and structural strength of leaves of Ficus. These results are used to develop recommendations for choice of MFT species and management strategies to improve the sustainability and productivity of livestock systems incorporating fodder trees