School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemRoasted legumes for lambs( 1997)Whole lupin (Lupinus angustifolius) and narbon bean (Vicia narbonensis) seeds were dry roasted at 100, 110, 120, 130, 140, 150 and 160C for 15, 30 and 45 minutes. The effect of roasting on in vitro solubility of crude protein (CP) and 'dry matter digestibility (IVDMD) were determined. From the solubility results, seeds roasted at 130C for 15, 30 and 45 minutes were chosen to study the effect of roasting on in situ ruminal disappearance of CP and dry matter (DM). From the in situ results seeds roasted at 130C for 45 minutes were chosen to be fed to crossbred wethers for nine weeks in a 2 (grain legumes) x 2 (raw vs roasted) experiment, in rations consisting of 70% concentrate (legume seed + barley) and 30% roughage (lucerne + oaten chaff). The effect of roasting on feed intake, growth, dry matter and nitrogen digestibility, nitrogen utilization, carcass weight and fat thickness were determined. For both legumes, CP solubility decreased with increasing temperature and time of roasting. The decrease was slightly lower in narbon than in lupin. CP solubility of lupin was decreased from 84.7% (raw) to 17.3% (160C, 45 min) and that of narbon from 68.0% (raw) to 18.3% (160C, 45 min). Dry roasting had no significant (P<0.05) effect on IVDMD measured over 72 hours. In situ DM and CP disappearance was estimated by incubating nylon bags in the rumen of sheep for 2, 6, 12 and 24 hours. Dry roasting significantly (R<0.05) reduced disappearance of CP from the bags with the reduction being slightly greater for lupin (a difference of 17.8% between the raw and 45 min sample after 24 hours of incubation) than narbon (a difference of 15.0% between the raw and 45 min sample after 24 hours of incubation) but had no significant effect on DM disappearance after 24 hours of incubation. Feed intake, growth, feed conversion ratio, dry matter digestibility, carcass weight and fat thickness were not affected (P>0.05) by roasting. Nitrogen retention, expressed as a percentage of nitrogen intake or as a percentage of nitrogen absorbed, was significantly (R<0.05) higher for lambs fed diets containing roasted narbon than for lambs fed diets containing raw narbon (as % of intake 20.3 is 12.3; as % of absorbed 25.6 vs 15.4), but was lower for lambs fed diets containing roasted lupin than those fed diets containing raw lupin (as % of intake 23.1 vs 30.9; as % of absorbed 27.3 vs 37.4). Dry roasting of lupin and narbon bean seeds decreased in vitro CP solubility and reduced ruminai disappearance of CP. Nitrogen utilization in lambs fed diets containing roasted narbon seeds was improved. Roasted lupin significantly (R<0.05) reduced nitrogen utilization in lambs. However, roasting these legumes had no significant (R>0.05) effect on growth.
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ItemFinishing prime lambs using pulse stubbles, and pulse and cereal grains in the Wimmera region of Victoria( 1998)Three trials were conducted as part of this study. The first trial evaluated faba bean and chick pea stubble as feed source for the finishing of lambs. The second trial evaluated the use of barley and field peas in feed lot rations for lambs, and the final trial evaluated narbon beans and vetch as substitute grains for field peas in feed lot rations for lambs. In the first experiment one hundred and twenty six Poll Dorset x (Border Leicester x Merino) mixed sex lambs with a mean liveweight of 40.0 kg � 0.3 kg were grazed on faba bean (FB) or chick pea (CP) stubble at a stocking rate of 6.5/ha and received a supplement of 300 g/hd/day of barley (+B) or were unsupplemented (-B). There was no significant difference (P>0.05) in average daily gain (ADG) over the duration of the trial between lambs grazing faba bean and chick pea stubble, supplemented with barley or unsupplemented. Lambs supplemented with barley tended (P- 4.06) to have a lower ADG in the first fortnightly period, and had significantly lower (P<0.05) ADG in the second period. This result is supported by the observation of supplemented lambs not grazing the stubble but waiting to be fed the barley supplement. This result was reversed in the third period when supplemented lambs tended (P~.06) to have a higher ADG, and in the final period when the ADG was significantly higher (P<0.05) than the unsupplemented lambs. There was a significant correlation (P<0.01 for faba bean stubble and P<0.05 for chick pea stubble) between ADG of unsupplemented lambs and the quantity of grain residue in the stubble. In the second experiment eighty Border Leicester x Merino mixed sex lambs with a mean liveweight of 27.3 kg � 0.2 kg were fed barley (B) or barley + field peas (B+FP) (60:40) either daily at 800 g/hd/day or ad libitum for 56 days following a 14 day introductory period. Hay was provided ad libitum. There was no significant difference (P>0.05) in ADG between lambs fed the treatment rations. Lambs fed B+FP were significantly different to lambs fed barley in the following: higher carcass weight (P<0.05); fatter (P<0.05); higher dressing percentage (P<0.01); higher estimated carcass weight gain (P<0.05) and lower dry matter intake to estimated carcass weight gain ratio (P<0.05). There was no significant difference (P>0.05) in any of the measured characteristics between lambs fed restricted or lambs fed ad libitum. In the third experiment twenty four Poll Dorset x (Border Leicester x Merino) lambs with a mean liveweight of 28.8 kg � 0.45 kg were individually penned and fed ad libitum a ration of narbon beans (NB), vetch (V) or field peas (FP) mixed with wheat and formulated to 16% crude protein. Milled hay was provided separately ad libitum. There was no significant difference (P>0.05) in growth rate, carcass weight, dressing percentage, feed intake, or dry matter intake to liveweight gain ratio between lambs fed the three rations. The growth rate and feed intake of lambs fed FP was more consistent than lambs fed NB or V. Scouring was observed in lambs fed V. There was highly significant (P<0.001) separation and selection of wheat in the NB and FP based rations. Further research needs to be carried out to evaluate meat quality of lambs fed narbon beans and vetch, in particular to determine if there is any effect on flavour of the meat. The use of pulse stubbles, combined with lot feeding can form a feeding system to enable lambs to be finished in the autumn-winter period in the Wimmera region. The growth rate of lambs grazing pulse stubbles is dependent on the quantity of grain residue on the ground. The growth rate can be maintained as grain level declines by the introduction of a barley supplement. Lot feeding can be used to finish lambs when pulse stubbles have been grazed out. A combination of a cereal grain and a pulse grain formulated to 16% crude protein can be fed ad libitum. Hay can be provided separately ad libitum, or a more controlled intake of hay can be achieved by feeding a calculated amount daily.
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ItemThe influence of concentrations of dietary lysine and energy offered during lactation on the lactation and subsequent reproductive performance of the first-litter sow( 1996)The first-litter sow has lower lactation and subsequent reproductive performance than older parity animals. The experimental work in this thesis was conducted to elucidate the influence of dietary energy and protein concentration during lactation on the lactation and subsequent reproductive performance of first-litter sows, whose litters were weaned at 3-4 weeks of age. In the first experiment, 140 first-litter sows were offered one of five diets, ranging in lysine content from 6.2 to 15.1 g/kg. Voluntary feed intake and sow liveweight loss were unaffected by dietary lysine concentration. However sow backfat loss was lowest for sows offered the lowest lysine diet and tended to plateau at a dietary lysine level of 10.6 g/kg. Piglet preweaning growth responded in a curvilinear manner to increasing lysine concentration. The results also indicated for sows nursing 9 or more piglets, that weaning to mating interval decreased with increasing sow dietary lysine concentration. Subsequent litter size was significantly higher for sows offered the two higher lysine diets during lactation, compared to the two lower lysine diets (10.7 vs 9.6 born alive, P<.05; s.e.d. 0.5). In the second experiment, 175 first-litter sows were offered one of five diets with a similar lysine:digestible energy (DE) ratio (0.88 to 0.85 g/MJ) but ranging in DE content from 12.6 to 15.1 MJ/kg. Voluntary food intake and piglet growth rate during lactation were unaffected by DE content of the diets. Sow liveweight loss during lactation declined with increasing energy content up to 13.8 MJ DE/kg. Backfat loss during lactation tended to be highest for sows offered the diet of lowest DE content and declined with increasing energy content up to 15.1 MJ DE/kg. The subsequent weaning to remating interval and litter size were unaffected by dietary DE content. In the third experiment, 204 first-litter sows were offered diets containing either 8.1 or 13.3 g lysine/kg during lactation. Voluntary food intake in lactation, piglet preweaning growth, sow liveweight and backfat loss during lactation, weaning to mating interval and subsequent litter size, were unaffected by dietary lysine concentration of the lactation diet. The number of corpora lutea and embryos were also not influenced by dietary lysine concentration during the preceding lactation. However, the data from those sows whose preweaning litter growth was in excess of 40 kg demonstrated a significant improvement in number of corpora lutea at the higher dietary lysine level. The results indicate that sow liveweight and fat losses during lactation appear to be more responsive to changes in DE concentration than changes in dietary lysine level. However, lysine concentration may limit piglet growth rate, weaning to mating interval and subsequent litter size. The results also suggest that improvements in subsequent litter size, observed when sows are offered high dietary lysine levels during lactation, may be due to an improvement in ovulation rate. These experiments suggest that current amino acid recommendations for lactating first-litter sows are inappropriate and may be constraining both milk production and subsequent reproductive performance.
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ItemEffect of tannins on the nutritive value of tropical shrubs( 1995)Three studies were conducted to assess the effect of condensed tannins (CT) on the nutritive value (NV) of some tropical shrubs. The first study involved two experiments (Experiments la and lb). Experiment la was designed to investigate the nylon bag dry matter digestibility (NBDMD) of 12 tropical shrubs (10 legumes and 2 non-legumes) varying in their content of extractable (ECT) and bound (BCT) condensed tannin. Samples were finely-chopped (- 3 mm) and incubated as either fresh or after oven-drying at 65C for 48 hours in the rumen of 5 steers. The contents of nitrogen (N), neutral (NDF) and acid (ADF) detergent fibres, lignin, ECT by vanillin (ECTvan) and butanol-HC1 (ECTbut) assay methods, protein-bound (PCT) and fibre-bound (FCT) were measured and the relationship between these plant constituents and the NBDMD were determined. Experiment lb was undertaken to determine the effect of drying method of forage samples on the chemical and CT contents, and NBDMD of 6 shrub legumes. A further purpose was to determine the effect of drying method on the prediction of NBDMD from the chemical and CT constituents. Forage samples were either freeze-dried (FD) at -30C or oven-dried (OD) at 65C for 48 hours and then ground through a 1 mm screen before the analyses or nylon bag digestion. The second study was an investigation of the effect of preparation method of fresh forage samples on the NBDMD of two leguminous shrub species, Calliandra calothyrsus and Lysiloma watsonii. Preparation methods included: fresh material coarsely (Ti) or finely (T2) chopped immediately after harvest and inserted in the rumen of steers within 30 minutes of harvest and preparation of sample; fresh material finely chopped and held for 6 hours before incubation either, in the oven at 65C (T3), in a sealed plastic bag and refrigerated at about 4C (T4) or in shade (wilted) under room temperature (approx. 23C, T5); unchopped fresh material was sealed in a plastic bag and refrigerated for 6 hours before being finely-chopped and inserted in the rumen immediately after preparation (T6). All samples were incubated in the rumen of steers for 48 hours. In the third experiment the effect of the addition of polyethylene glycol (PEG) on in vitro dry matter digestibility (IVDMD) of freeze- (FD) and oven-dried (OD) samples of 4 shrub species was determined. Two in vitro techniques were used, the rumen-liquor-pepsin (RLP) and the pepsin-cellulase (PC) methods. Polyethylene glycol was added as a solution at 0, 80, 160, 320 or 640 mg/g DM of sample incubated. The results of the chemical analysis showed significant (P<0.001) variation between species in Experiment 1a but not in Experiment 1b. The contents of ECT and BCT (PCT+FCT) also varied between species and method of analysis, although these differences were not tested. The ranges of the content of ECT in FD samples for vanillin and butanol- HC1 respectively were: 0.35-11.62% and 0-9.34% in Experiment 1a, 0.3-6.5% and 0.1- 7.6% in Experiment 1b. Nylon bag dry matter digestibility was significantly (P<0.001) different between species, ranging from 17-81% in the fresh samples and 75-88% in FD samples. There were significant (P<0.001) linear correlations between NBDMD and N (r = 0.438), NDF (r = -0.663), ADF (r = -0.666) lignin (r = -0.810), ECTvan (r = -0.548), ECTbut (r = -0.620) and total CT (r = -0.601) but not with PCT (r = -0.210) or FCT (r = -0.389) (P>0.05). Oven-drying significantly (P<0.001) increased the contents of NDF, ADF and lignin in Experiment 1a but not in Experiment 1b. The effect of oven-drying on the content of ECT or BCT was not consistent between species or drying methods (FD vs. OD). While some forms of CT were increased by oven-drying in some species, others were decreased but this pattern was not similar for all species. Oven-drying at 650C significantly (P<0.001) depressed NBDMD of C. calothyrsus, L. watsonii and A. currassavica (Experiment 1a), and C. calothyrsus and L pallida (Experiment 1b). The correlation between NBDMD and lignin was significant when FD samples were used (r = -0.55; P<0.001) but not when OD samples were used (r = -0.29; P>0.05) for both the analysis and digestion study. The relationship between NBDMD and other chemical or CT component was not affected by drying. Preparation method of fresh forage significantly (P<0.001) affected NBDMD of both C. calothyrsus and L. watsonii. Coarse-chopping (- 15 mm) gave lower estimates of NBDMD compared to fine-chopping (- 3 mm). Holding freshly-chopped samples for 6 hours significantly (P<0.05) depressed NBDMD and this depression was related to temperature and was greatest in OD samples. In vitro dry matter digestibility differed significantly (P<0.001) between species, method of drying samples, the level of PEG and some of the interactions between these factors. Addition of PEG at 80-160 mg/g DM of sample significantly (P<0.05) improved IVDMD of the tannin-containing shrubs. Increasing the level of PEG beyond 160 mg up to 640 mg/g DM did not show any further improvement in IVDMD. Generally, the PC method gave significantly (P<0.05) higher IVDMD than the RLP method at all levels of PEG (62.77 vs. 54.14%, s.e.d. = 0.28). Similarly, FD samples were significantly (P<0.05) higher in IVDMD than OD samples (59.32 vs. 57.60% respectively, s.e.d. = 0.28). It was concluded from these studies that the composition of CT varied between assay technique and species. Also, the effect of CT on the NV of tanninferous tropical shrubs also varied between species. The variation in the effect of oven-drying on the chemical and CT contents and the digestibility of shrubs was attributed to the differences in the composition and nature of CT present in individual shrubs. It appears that the depressing effect of CT on digestibility was primarily due to the free or extractable form rather than the bound CT in the species studied. However, in addition to CT, other factors such as the fibre and lignin components of shrubs also affect digestibility. Method of preparation of fresh samples should be taken into consideration when conducting a chemical analysis or nylon bag digestibility study. Whenever possible, freshly-chopped forage materials should be used. Otherwise, fresh materials can be stored under low temperature (VC) prior to incubation in the rumen. Polyethylene glycol improved IVDMD irrespective of in vitro technique or drying method but the efficiency of PEG varied from one species to another since the nature and reactivity of CT vary between species. Polyethylene glycol was not able to overcome the depression in IVDMD associated with oven-drying probably due to the formation of some irreversible CT-protein complexes. The Pepsin-cellulase in vitro technique gave higher estimates of IVDMD than the RLP technique after 48 hours of incubation. More studies were suggested to further understand the anti-nutritional effects of CT, most especially in dried forages. Characterisation of tannins in plant materials should precede their quantitative determination. Also, more in vivo studies and feeding trials are recommended since in addition to digestibility and chemical composition, the NV of forage is a function of voluntary feed intake and the efficiency of conversion of digested nutrients to tissue gain and reproductive performance.
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