Effect of by-product gypsum application rate to grass pasture,grass hay,and corn silage on fermentation by rumen microorganisms in continuous culture

A dual-flow continuous culture fermenter system was used to investigate ruminal fermentation in response to increased by-product gypsum application rate of three forages. The treatments included 0, 22, 45, and 90 tonnes/ha by-product gypsum applied to grass plots and 0, 22, and 45 tonnes/ha by-product gypsum applied to corn plots. Forage was harvested to represent grass pasture (GP), grass hay (GH), and corn silage (CS), dried, ground, and fed to fermenters at a rate of 60 g dry matter (DM)/day. Organic matter (OM) and neutral detergent fiber (aNDF) digestibilities, rumen pH, total volatile fatty acid (VFA) production, and N metabolism were not affected by gypsum application rate for all forage types. The GH had greater sulfur content than recommended as the maximum tolerable level by the National Research Council (NRC). The results of this study indicate that ruminal fermentation was not compromised when by-product gypsum was applied to GP, GH, or CS at rates up to 90 tonnes/ha. By-product gypsum application to pastures and crops shows promise as an economical soil amendment to reduce dissolved phosphorus loss in runoff, although potential animal health issues should be further evaluated.     

Preference of horses for grass conserved as hay,haylage or silage

The purpose of this experiment was to determine if different methods of forage conservation influenced horse preference for conserved forages. Silage, haylage with two different dry matter (DM) levels and hay was produced from the same grass crop at the same botanical maturity stage. Four horses were simultaneously offered the four forages (1 kg DM of each forage) once daily for four consecutive experimental periods, each period consisting of 5 days. On each experimental day, the horses were observed for 2 h and their first choice, eating time and forage consumption was registered for every forage. The number of times each horse depleted individual forages and the number of times each horse tasted or smelled a forage, but left it in favour of another forage, was also recorded. Silage had the highest rate of consumption (0.90 kg DM/day, S.D. 0.14) and longest eating time (28.4 min/day, S.D. 5.16). Hay had the lowest rate of consumption (0.23 kg DM/day, S.D. 0.14) and shortest eating time (6.8 min/day, S.D. 4.08), while the haylages were intermediate. Silage was the first choice 72 of 84 times (85%). Hay was never completely consumed and silage was never left in favour of another forage after smelling or tasting it. We conclude that the forage conservation methods had an impact on horse preference in favour of silage, even if the reason for silage preference remains to be explained.     

The effect of heather supplementation on gastrointestinal nematode infections and performance in Cashmere and local Celtiberic goats on pasture

A study was performed on 48 adult dry goats (16 local Celtiberic and 32 Cashmere does) at pasture and naturally infected with gastrointestinal nematodes to investigate the effects of heather supplementation on faecal egg count(s) (FEC) and live weight changes. The experiment was carried out in a mountain area in the north-west of Spain from June to November in 2003. Two plots of 10,550 and 9,050 m² with perennial ryegrass/white clover (Lolium perenne/Trifolium repens) pastures were established and a total of 24 goats (8 local Celtiberic does and 16 Cashmere does) were randomly allocated to each plot. The trial consisted of comparing live weight changes and FECs in goats fed heather supplement (treated group) or not (control group). A supplement of freshly cut heather was offered ad libitum to the treated group every 3 days in the morning. Cashmere does showed a significantly (P < 0.001) lower live weight decrease than the Celtiberic goats. The goats supplemented with heather showed a lower FEC than compared controls and this effect was significant (P < 0.05) in August and in the following controls (September, October and November). Two goats died before November in the control group. In conclusion, it seems that the availability of heather reduces the FEC in goats grazing ryegrass/white clover pastures and tends to improve their live weights.     

Characterization of immune responses against gastrointestinal nematodes in weaned lambs grazing willow fodder blocks

A 131-day rotational grazing experiment was conducted in the summer autumn of 2007/2008 to compare effects of feeding condensed tannin (CT)-containing willow (Salix spp.) fodder blocks (i.e., silvopastoral system) or perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) control pasture upon the immune response to gastrointestinal nematode parasite infection in Romney weaned lambs. Groups of lambs (n = 40) were allocated to either willow fodder blocks or control pasture; half of each group (n = 20) were regularly-drenched with anthelmintic at approximately 21 day intervals, whilst the remaining 20 weaned lambs were not drenched unless pre-determined faecal nematode egg counts (FEC) were reached, when all weaned lambs in that group were drenched with anthelmintic (i.e., trigger-drenching). Metabolizable energy and CT concentrations were higher in willow fodder versus pasture herbages. Weaned lambs grazing willow fodder blocks had lower live weight gain (92 g/day) and carcass weight (14.4 kg) than those grazing control pasture (134 g; 15.3 kg), with no effect of anthelmintic drenching. Regular anthelmintic treatment maintained similar and low FEC up to day 82, which then increased, whilst trigger-drenched lambs grazing willow fodder blocks had higher FEC than lambs grazing control pasture on three out of eight occasions. As judged by faecal larval cultures, grazing willow fodder blocks reduced the relative proportions of abomasal-dwelling parasites (Haemonchus contortus and Teladorsagia spp.). Trigger-drenched willow fodder block-fed sheep had higher platelet, eosinophil, total white blood cell and lymphocyte counts, greater CD21⁺ and greater γδ (Gamma Delta) TCR⁺ (T cell receptor) lymphocyte subsets than control pasture-fed sheep, and higher plasma levels of Immunoglobulin A (IgA) specific for carbohydrate larval antigen (CarLa) on day 105 (P<0.001). None of these parameters were affected by grazing treatment in regularly-drenched lambs. Higher immunological measurements in trigger-drenched lambs grazing willow fodder blocks could be due to higher larval intake and/or to the effects of secondary compounds in willow fodder blocks priming the immune system. Further research is required to separate these effects.     

Fecal nitrogen to estimate intake and digestibility in grazing ruminants

This study aimed at evaluating forage intake and digestibility in ruminants using fecal nitrogen content, as well as validating a non-linear model to estimate digestibility in ruminants. A total of 58 conventional metabolism trials, carried out with sheep fed 27 forages (offered pure or in mixture) used in Rio Grande do Sul (RS) during the period 1969–1989 was analyzed. OM intake and OM digestibility (OMD) results were regressed linearly against fecal N, and OMD was also estimated from fecal crude protein (N × 6.25) content by a non-linear regression model. Fecal nitrogen excretion estimated forage intake in sheep with an R² = 0.73, whereas a low R² value of 0.36 was observed for OMD estimates. The equation obtained using the non-linear model was OMD = 0.7326 ? 0.3598 exp [(?0.9052 CP (g/kg OM))/100]. The parameters a (0.7326) and b (0.3598) estimated by the equation for all forages were significant (P<0.00001) and there was no effect of type of forage (P=0.38). The mean prediction error (MSPE), was 0.2379, indicating that the equation fit well to the data. The difference between estimated and observed organic matter digestibility was mainly caused by random variation (0.9765). The results indicated that the equation using the non-linear model developed with all forages can be used with enough precision to estimate the OM digestibility of forage consumed by sheep in Rio Grande do Sul.     

Biomass and quality changes of forages along land use and soil type gradients in the riparian zone of Lake Naivasha,Kenya

The recession of the water level of Lake Naivasha has incrementally exposed land surfaces creating a chronosequential transect representing durations of 1–30 years of exposure to grazing. This chronosequence provides a unique model to study the effects of land use duration on resource availability and resource base quality. Particularly, pasture quality changes in the riparian land of tropical fresh water lakes have so far not been studied. We assessed the effect of the duration of exposure to grazing on the biomass production, crude protein content and energy quality of pastures in a 4 × 4 latin square design (4 chronosequence positions × 4 soil types). Species composition was recorded and biomass was sampled at monthly intervals from February to August 2011. Soil moisture was recorded using frequency domain reflectometry sensors. Vegetation samples were analyzed for dry matter, nitrogen and metabolizable energy. Increased land use duration favored a shift in species dominance from Pennisetum clandestinum to Cynodon plectostachyus, which was associated with a reduction in dry matter yield and increased plant nitrogen content. All measured variables tended to be higher in soils formed on alluvial than in those formed on lacustrine deposits. Increased soil N and gravimetric moisture content stimulated biomass accumulation. The crude protein yield and metabolizable energy changed with phenological stages of the pasture and declined significantly towards maturity (seed setting of grasses). Continuous grazing and reduced soil moisture content, both during low rainfall and increased distance from the lake shore, affected the composition of pasture grasses as well as forage yield and quality. This may thus differentially affect the suitability of the riparian land as pasture ground and feed resource area for grazing animals.     

Weight gains of meat goat kids on wheat (Triticum aestivum L.) pastures fertilized at different nitrogen levels

Wheat (Triticum aestivum L.) pastures are increasingly being used for cool-season forages to complement range-based goat production systems in southern USA. Because goats are more selective than cattle, ideal nitrogen (N) fertilizer rates already established for wheat grazed by cattle may be different for goats. Weight gains of Boer X Spanish doe kids (average 17 kg) as well as forage yields and crude protein (CP), acid detergent fiber (ADF) and acid detergent lignin (ADL) concentrations were measured for two winter seasons on replicated wheat paddocks fertilized with 0, 56, 112 and 224 kg N/ha per season in split autumn/spring applications at Stephenville, TX, USA. Animals were stocked in the pasture at 20 head/ha from January to April 2003 (478 mm rainfall from September to March) and 2004 (355 mm rainfall). Available forage ranged from 50 to 200 kg/ha in January and from 2300 to 6300 kg/ha in April in the 0 and 224 kg N/ha paddocks, respectively. Crude protein dry matter (DM) concentration ranged from 25 to 34% (0 and 224 kg N/ha, respectively) in January, but down to 13 and 22% across treatments in April. Average daily gains (ADG) over the 90-day trial were similar both years, 68 g per head per day for the 0 N treatment and undifferentiated among the fertilized paddocks, all near 90 g per head per day. Results indicate that N fertilizer rates above 56 kg/ha per season do not increase ADG/kid, but will increase ADG/ha if stocking rates are adjusted for forage production.     

Effect of supplementation with pelleted citrus pulp on digestibility and intake in beef cattle fed a tropical grass-based diet (Cynodon nlemfuensis)

Citrus pulp is an important by-product for sub-tropical and tropical ruminant animal production. In this study, three steers (average body weight = 324 ± 16 kg) were randomly assigned to three levels of pelleted citrus pulp (PCP) supplementation (0, 1.25, and 2.5 kg animal⁻¹ d⁻¹; as-fed) in a 3 × 3 Latin square design to evaluate its effects on forage intake, digestion, and ruminal pH. The basal diet was stargrass (Cynodon nlemfuensis) harvested and chopped every day and fed fresh. Supplementation with increasing amounts of PCP tended (P≤0.10) to result in a linear increase in digestibility of total diet dry matter (DM) and organic matter (OM), but no effects were noticed for digestibility of forage DM or total diet neutral detergent fiber. Forage DM intake decreased linearly (P=0.03) with increasing PCP supplementation, although the decrease tended (quadratic; P=0.08) to be of greater magnitude at the highest level of supplementation. Both a linear increase (P<0.01) and a quadratic trend (greatest increase with first level of supplementation; P=0.09) were also observed for intake of total digestible OM. Average ruminal pH was between 6.6 and 7.2 and was not affected (P=0.29) by supplementation treatment. Although supplementation with PCP depressed forage consumption somewhat, little effect on forage digestion was observed. The provision of digestible OM in the form of supplement was greater than that lost via depressed forage consumption, resulting in an overall increase in energy supply. Our results suggest that high levels of citrus pulp to beef cattle can lower forage intake, but increase total energy intake. High levels of citrus pulp supplementation could be beneficial in combination with forages high in rumen dagradable protein. Systems using grasses with higher ruminally degradable protein content than we used, may benefit from this extra supply of energy which should be tested in a further experiment.     

Evaluation of green forage intake and digestibility in ruminants using near infrared reflectance spectroscopy (NIRS): Developing a global calibration

The objective of this study was to evaluate the potential of near infrared reflectance spectroscopy (NIRS), applied to forage and/or faeces, to estimate the in vivo organic matter digestibility (OMD) and the organic matter voluntary intake (OMVI, g/kg metabolic weight [BW^0.75]) for a wide range of temperate forages. Two different databases, in terms of forage species and development stages were studied. The first one included two grass species and two forage mixtures for which OMD and OMVI were continuously measured during the grass-growing seasons (spring and summer). The second one contained a large set of grass and legume species and forage mixtures (142 trials) for which OMD and OMVI were measured.Forage and faeces samples were submitted to NIRS analysis and predictive calibrations were developed from forage spectra, faeces spectra, forage and faeces subtracted spectra, and faeces and forage concatenated spectra. Working on faecal spectra (alone or concatenated) enabled us to develop the best calibration equations for both OMD and OMVI estimation. The coefficient of determination (R²) was greater than 0.8. The standard error of cross validation (SECV) for OMD and OMVI was 0.021 and 4.51 g/kg BW^0.75, respectively, and the accuracy was similar to that obtained with other predictive methods. With regard to the faecal spectra (second derivative mode), the fat absorbency at wavelengths of 1730, 2310 and 2350 nm was higher when the corresponding forage was highly digestible and ingestible.In conclusion, applying NIRS to faeces is a rapid and easy analytical method that could be an interesting tool for managing grazing ruminants and optimising their performance.     

Seasonal variations in fatty acid composition of pasture forage plants and CLA content in ewe milk fat

The relations between fatty acids (FAs) composition of pasture forage plants and the content of conjugated linoleic acid (CLA) as a total content of cis-9, trans-11 + trans-7, cis-9 + trans-8, cis-10 CLA isomers in ewes’ milk fat during natural pasture season (April–September) were investigated. The extracts of ewes’ milk fat samples as well as the pasture samples were analyzed for fatty acid composition by capillary gas chromatography with flame ionization and mass spectrometric detection. α-Linolenic, linoleic, and palmitic acids were predominant in pasture plants, and their contents varied during pasture season. The most abundant and most varied fatty acid compound in pasture plants was α-linolenic acid. Its content significantly decreased from 62% to 39% (of total FA) (P < 0.001) from May to August, and subsequently it slightly (57%) increased from August to September (P < 0.05), compared with the beginning of pasture season. Similarly, the content of CLA in ewes’ milk fat decreased from 2.4% in May to 1.3% in August (P < 0.001), and subsequently it rose to 2.6% in September (P < 0.001). The α-linolenic/linoleic acid ratio in the pasture sample decreased from 4.36 in May to 1.97 in August (P < 0.001), and subsequently it increased to 3.14 in September (P < 0.001); thus, it reached the level approaching to that at the beginning of pasture season. The pasture seasonal variations in the ratio were directly proportional to the corresponding content of CLA and indirectly proportional to the ratio in ewes’ milk fat. The results suggest that the seasonal variations in CLA content in ewes’ milk fat are related primarily to the seasonal variation in α-linolenic acid content in grass lipids.     

Intake,digestion and selection of roughage with different staple lengths by sheep and goats

The diet selection, ingestive and digestive responses of goats and sheep offered a single forage, which was prepared with three staple lengths: long (L), medium (M) and short (S) (mean particle size (mm): 13.29, 7.26 and 0.69, respectively) were studied in three experiments. The sheep (Scottish Blackface wethers) increased their dry matter intake (sheep DMI: 60.1, 61.1 and 66.2 g DM/(kg W^0.75) per day for L, M and S) and reduced mean retention time (MRT) of the undigested residues (sheep MRT: 54.6, 52.9 and 45.9 h for L, M and S) and digestive efficiency (sheep DM digestibility: 0.524, 0.522 and 0.493 for L, M and S) with the reduction in forage particle size. The respective responses of goats (feral crosses) were not modified with forage staple length (goat DMI: 68.1, 65.9 and 67.3 g DM/(kg W^0.75) per day for L, M and S); (goat MRT: 38.7, 39.3 and 41.1 h for L, M and S); (goat DM digestibility: 0.495, 0.475 and 0.480 for L, M and S). However, both species had similar intakes of digestible dry matter (DDMI) on all staple lengths (mean DDMI: 32.0 and 32.6 g DDM/(kg W^0.75) per day for sheep and goats). On the longer staple lengths (L and M) goats masticated the fibre into smaller particles than did sheep and had (P<0.01) a greater proportion of small particles in their boli (mean: 0.45 and 0.30 for goats and sheep). The selection of components within the forage offered was different for the two species. Goats consumed forage of lower nitrogen (N) (P<0.01) and in vitro organic matter digestibility (OMD) (P<0.05) and higher neutral detergent fibre (NDF) (P<0.01) contents than sheep. This was associated with the residues from sheep having a coarser texture than those of goats. When the forages of different staple lengths were offered in pairs to the animals, there was no evidence for selection of forage types by either species. It would appear that the greater ability of goats to chew efficiently provides a reason for the different responses to staple length in intake, digestibility and MRT by the two species.     

Effect of high tannin grain sorghum on gastrointestinal parasite fecal egg counts in goats

The objective of three experiments was to determine the influence of high condensed tannin (CT) grain sorghum on gastrointestinal parasite fecal egg counts (FEC). Sixteen naturally infected Boer crossbred mixed-sex goats were used. Animals that were supplemented with grain daily were removed from pasture and placed in individual pens and fed treatment diets for 21 or 14 days (Experiment 3). Goats were allowed ad libitum access to water and diets containing high or low CT cracked grain sorghum. On day 0 and every 7 days thereafter, PCV, FEC and FAMACHA^® eyelid color scores (EYE; Experiment 1 only) were recorded. For Experiment 1, percentage of animals dewormed, PCV and EYE were not influenced by treatment and averaged 13.6 ± 4.5% per treatment period, 23.4 ± 0.8% and 3.2 ± 0.12, respectively, for all animals. The FEC increased after day 0 for control but not high tannin grain sorghum fed goats (treatment by day interaction, P < 0.02). As expected, EYE and PCV were negatively related (r = −0.45; P < 0.0005). For Experiment 2, there was no influence of diet on PCV or FEC, but there was an effect of day on FEC (P < 0.002) in which all goats had higher FEC on day 0 (1956 ± 219 eggs/g) than any other sampling day. For Experiment 3, there was no effect of feeding high CT grain sorghum on FEC (2992 ± 591 eggs/g) or PCV (25.1 ± 0.5%). In these studies, high CT grain sorghum did not consistently influence FEC and did not impact PCV or number of animals requiring chemical anthelmintic treatment.     

Effect of harvesting period on the nutritive value of rice grass (Echinochloa sp.) hay given as sole diet to lambs

Data regarding the influence of maturity within the vegetative stage of tropical grasses on forage quality are limited and conflicting. The change in chemical composition of rice grass (Echinochloa sp.) hay harvested at 32, 46, 72 and 90 days of regrowth, and its effect on intake, digestibility, ruminal fermentation, rumen microbial protein synthesis (Experiment 1) and splanchnic oxygen uptake (Experiment 2) by lambs was evaluated. Except intake of indigestible neutral detergent fibre (NDF) which was similar for all treatments, intake of all hay components and the apparent digestibility of dry matter, organic matter (OM), NDF, N, as well as OM and N true digestibility, N retention and rumen microbial protein synthesis decreased linearly (P < 0.05) with increased regrowth age. Rumen fluid pH, ammonia N and peptide concentrations were similar for all treatments while sugars and amino acid concentrations decreased linearly with increased regrowth age of rice grass (P < 0.05). Passage rate of particles through reticulum-rumen (PRrr) was quadratically related (P < 0.05) to regrowth age. The highest PRrr and, consequently, the lowest retention time in the reticulum-rumen were obtained at 72 days of regrowth. There was a quadratic effect (P < 0.05) on net portal-drained viscera (PDV) flux of oxygen and heat production, while OM intake, portal blood flow and heat production as proportion of digestible energy (DE) intake were not affected by the increased regrowth age of rice grass. The highest means of oxygen uptake and heat production by PDV tissues were in 72 days treatment. In the whole splanchnic metabolism assay neither hay intake nor blood flow, oxygen uptake or heat production were affected by forage regrowth age. In conclusion, the nutritive value of rice grass hay decreased as regrowth age increased from 32 to 90 days due to decrease both OM intake and digestibility.     

Ruminal nitrogen disappearance from sod-seeded cereal grain forages in Northern Arkansas

Wheat (Triticum aestivum L.), oat (Avena sativa L.) and rye (Secale cereale L.) were overseeded into a dormant bermudagrass (Cynodon dactylon (L.) Pers.) sod and harvested on six dates throughout the spring. Plant growth stage was documented for each forage on each harvest date, and harvested forages were subsequently evaluated for forage quality characteristics. Four ruminally cannulated steers were used to evaluate disappearance kinetics of nitrogen (N) by an in situ method. All forages had high concentrations of N (≥31.1 g kg⁻¹ DM) throughout harvest dates in March. By 15 April, rye had reached a substantially more advanced growth stage than either wheat or oat. This trait, coupled with the concurrent taller growth habit, caused concentrations of N in rye to decline (P<0.05) rapidly between the 24 March and 4 May harvest dates. The effective ruminal disappearance of N remained high (≥790 g kg⁻¹ N) for all forages harvested through mid-April, thereby indicating that these cereal-grain forages exhibit the same characteristics of high N disappearance and low potential ruminal escape that are commonly observed in other high-quality cool season grasses harvested at similar growth stages. The effective disappearance of N reached a minimum (P<0.05) for all forages immediately before grain fill. Generally, substantial increases (P<0.05) in effective ruminal disappearance of N were observed as these forages partitioned N into the filling grain head. Fractional rates of N disappearance for wheat and rye were extremely rapid (≥0.383 h⁻¹) during grain fill. However, rye also exhibited an extremely rapid disappearance rate (0.548 h⁻¹) immediately prior to the onset of grain fill that was not observed for wheat (0.085 h⁻¹) at an identical growth stage. Parameters associated with disappearance kinetics can be related to growth stage at harvest by linear and polynomial regression techniques, although the best fit model was dependent on forage type.     

The effect of inclusion of lupins/triticale whole crop silage in the diet of winter finishing beef cattle on their performance and meat quality at two levels of concentrates

This study investigated the performance and instrumental meat quality of finishing beef steers offered grass silage (GS), grass silage:maize silage (GS:MS) and grass silage:lupins/triticale silage (GS:LT). The lupins/triticale silage was grown as either two separate crops in the same field and harvested together (LT1) or grown and harvested as a mixture (LT2). The silages were offered to eighty continental cross beef steers, initial live weight 530 ± 47.7 kg and 18 ± 1.6 months of age and were supplemented with 3 or 6 kg concentrates fresh/head/d. Silage was fed ad libitum with the mixtures offered at a ratio of 60 GS:40 maize silage (MS), LT1 or LT2 on a dry matter (DM) basis and concentrates were offered once (3 kg) or twice (6 kg) daily on top of the silage. Animals were slaughtered in three batches after 100, 117 and 124 d on experiment. The LT1 and LT2 produced yields of 8.7 and 7.5 kg DM/ha and the silages were poorly fermented as demonstrated by high ammonia-N concentration (182 and 173 g/kg total N), low lactic acid (9 g/kg DM) and high pH (5.0 and 4.7). Silage type had no significant effect on slaughter live weight, liveweight gain, carcass gain, forage DM intake (DMI), total DMI or feed efficiency expressed as kg DMI/kg liveweight gain or kg DMI/kg carcass gain. Silage type had no effect on carcass characteristics or instrumental meat quality. The results of this study demonstrate that offering lupins/triticale silage in combination with high quality grass silage (D-value greater than 700) at a ratio of 60 grass silage:40 LT1 or LT2 on a DM basis had no effect on animal performance, carcass characteristics or meat quality parameters relative to high quality grass silage offered alone or in combination with maize silage.     

The consequences of short-term grazing of bioactive forages on established adult and incoming larvae populations of Teladorsagia circumcincta in lambs

The objective of this study was to investigate the consequences of short-term grazing on bioactive forages on (i) the viability and fecundity of established adult Teladorsagia circumcincta population and (ii) the establishment and development of incoming T. circumcincta infective larvae. Forty-eight, parasite naive, 3-month old, grazing lambs were artificially infected with 8000 infective larvae of T. circumcincta on day 1 of the experiment. On day 21 p.i., lambs were allocated to one of three bioactive forage grazing treatments; chicory (Cichorium intybus), sulla (Hedysarum coronarium), lotus (Lotus pedunculatus), and the control grass/clover (Lolium perenne/Trifolium repens) forage. On day 28 of the experiment a second dose of 8000 T. circumcincta infective larvae was administered to the lambs to investigate the effects of forages on the ability of infective larvae to establish within the host. All animals were slaughtered for worm recovery on day 35, while liveweight gain, feacal egg counts (FEC) and total worm egg output were monitored regularly throughout the experiment. Although FEC or total egg output were similar among the groups, adult worm burdens at slaughter were significantly affected (P<0.05) by forage treatment during the 2 week grazing period. Lambs grazing chicory had the lowest adult worm burdens and significantly lower numbers of male worms compared to those grazing on grass/clover (P<0.01), while the lambs grazing on sulla or lotus had similar adult populations to grass/clover fed animals. The results from the worm recoveries of the second dose (immature worm burdens) were affected by physiologically and/or immunologically mediated mechanisms, which reduced larval establishment in all treatments. Nevertheless, immature worm burdens at slaughter were similar between chicory, sulla and grass/clover group, while the immature worm recoveries from the lotus group were significantly higher (P<0.05) compared to those from lambs grazing grass/clover. Overall, the results of the present study support the view that chicory can be a promising candidate species in pasture management practices to control T. circumcincta burdens.     

Effect of partial replacement of concentrates with jackfruit (Artocarpus heterophyllus) leaves on growth performance of kids grazing on native pasture of Tripura,India

Fifteen Black Bengal kids of about 3 months of age and body weight ranging from 3.8 to 4.9 kg were randomly distributed into three groups of five. Kids grazed native pasture 8 h/d. The kids in group I received supplementary concentrate (maize 35%, mustard cake 32%, rice bran 30%, mineral mixture 2% and common salt 1%) at approximately 2% of BW. However, 25 and 50% of the concentrate was replaced with jackfruit leaves for groups II and III, respectively. Total dry matter intake (DMI) was significantly higher in groups II and III than for group I due to greater forage consumption. Digestibility of CP (P < 0.05) decreased and that of NDF increased (P < 0.01) with increasing level of jackfruit leaves in the diet. Digestibility of ADF (P < 0.01), hemi cellulose (P < 0.05) and cellulose (P < 0.01) was higher in groups II and III in comparison to group I. Ruminal pH and TVFA concentration were not significantly different among the groups; however, rumen ammonia-N concentration decreased (P < 0.01) with increased level of jackfruit leaves in the diet. Similarly, plasma urea nitrogen and blood glucose levels were also reduced (P < 0.05) with increasing level of jackfruit leaves in the diet Average daily gain (ADG) was 47.33, 45.11 and 35.56 g/d in groups I, II and III, respectively. ADG and DMI/kg gain were not adversely affected when the level of replacement was restricted to 25%; however, at the 50% of replacement both parameters were adversely affected (P < 0.05). From the results of this experiment, it was concluded that jackfruit leaves might replace 25% of the supplemental concentrate for growing kids grazing in native pasture of northeast India.     

Responses of hair and wool sheep to a single fixed dose of infective larvae of Haemonchus contortus

Body weights, fecal egg counts (FEC), and packed cell volumes (PCV) of hair sheep and wool sheep crossbred lambs were compared over 8 weeks following administration of a single dose of approximately 10,000 third-stage larvae of Haemonchus contortus. Hair sheep lambs (n=17) were reciprocal crosses between mainland USA populations of Barbados Blackbelly (BB) and Virgin Islands White (VIW) sheep. Wool sheep lambs (n=64) were from a crossbred composite of 50% Dorset, 25% Rambouillet, and 25% Finnish Landrace breeding. Lambs of both breed types continued to grow during the period of infection. Mean weights were higher for wool lambs (39.7±0.8 kg) than for hair lambs (28.2±1.5 kg). FEC increased to week 5 in both breed groups and remained elevated in wool lambs through week 7 but declined sharply in hair lambs after week 5. Mean FEC for weeks 4 through 8 were 4011±361 eggs per gram of feces (epg) in wool lambs, and 1135±196 epg in hair lambs. PCV declined through week 7 in wool lambs but stabilized and then increased after week 4 in hair lambs. Mean PCV in weeks 4 through 8 were 22.4±0.3% in wool lambs and 24.3±0.5% in hair lambs. These results suggest that Caribbean hair breeds may be able to contribute significantly to development of parasite-resistant sheep populations.     

Seed and forage yield,and forage quality determinants of nine legume shrubs in a non-tropical dryland environment

The objective was to identify legume shrub species for development of agroforestry technologies based on seed and forage (leaves and twigs < 10 mm diameter) yield, and determinants of forage quality. Ten individual plants of Bituminaria bituminosa ‘Ecotypes 1’, B. bituminosa ‘Ecotypes 2’, Medicago citrina, and M. arborea from Spain; Colutea istria and Onobrychis aurantiaca from Syria; C. istria from Jordan; Chamaecytisus mollis from Morocco; and Coronilla glauca from France were randomly selected from plots established in a non-tropical dryland environment in northwest Syria in 2000. Five individual plants of each species were cut back to 0.5 m above ground in March 2004. Coppice regrowths were pruned in December 2004 and April 2005 to determine forage yield and proportion of forage in the total above ground biomass (PEFB). Forage samples were analyzed for concentrations of crude protein (CP), lignin(sa), acid detergent fibre (ADFom), neutral detergent fibre (aNDFom), in vitro organic matter (OM) digestibility (IVOMD), and in vitro 24 h gas production (IVGP24h). Matured seeds were hand harvested from the remaining five plants of each species to estimate seed yield. Forage (21–250 kg DM/ha) and seed (0–200 kg DM/ha) yields; PEFB (0.22–0.96); and concentrations of CP (85–115 g/kg DM), lignin(sa) (14–42 g/kg DM), ADFom (94–170 g/kg DM), aNDFom (122–217 g/kg DM), IVOMD (456–617 g/kg OM), and IVGP24h (27–42 ml 200 mg/DM) varied (P<0.05) among shrub species. The IVOMD and IVGP24h were positively correlated (r = 0.75, P<0.032), whereas IVOMD and IVGP24h were negatively correlated with ADFom, lignin(sa) and aNDFom. In terms of forage and seed yields and determinants of forage quality, C. istria from Jordan, M. arborea, B. bituminosa ‘Ecotype-2’, C. istria and O. aurantiaca have higher potential than C. mollis, C. glauca and B. Bituminosa ‘Ecotype-1’ for the development of agroforestry technologies in non-tropical dry areas.     

Effects of yak dung patch dropped in cold season on soil and pasture on the Qinghai-Tibetan Plateau

To clarify how dung patches from grazing yaks affect soil and pasture in the alpine meadow of Qinghai-Tibetan Plateau, yak dung was collected, mixed and redistributed in a cold grazing season. The soil physical and chemical properties and forage growth were then monitored under the yak dung patch, and 10 cm and 50 cm from the edge of yak dung patches. The result has shown that yak dung significantly improved soil moisture, total organic matter, and soil available N and P under or close to the dung patches. The forage production at 10 cm from the dung patch (303 g/m²) was significantly higher than that at 50 cm from the dung patch (control) (284 g/m²) in the second year, while the production was similar to the control in the first and the third year. The process of yak dung decomposition was slow and yak dung remains were observed 3 years after the drop. The dung patches also formed a strong ‘shell’, very difficult for plant underneath to penetrate and grow. Therefore, almost all plants under yak dung patches died, leading to decline in forage yield in the first, second, and the third year. In practice in the Qinghai-Tibetan Plateau regions, yak dung is often collected as fuel by the local farmers. Removing yak dung from alpine meadow may on one hand lead to losses in soil nutrients, but on the other hand reduces some of the negative effects, e.g. the reduction of forage yield under yak dung patches.