A. J. Ayala-Burgos

Assessing the efficacy of Duddingtonia flagrans chlamydospores per gram of faeces to control Haemonchus contortus larvae.

The aims were (a) to quantify the number of Duddingtonia flagrans chlamydospores per gram of faeces (CPG) recovered from sheep administered with different oral doses and, (b) to describe the relationship between CPG and eggs per gram of faeces (EPG) on the efficacy to reduce Haemonchus contortus infective larvae. Three doses of chlamydospores per kg BW were orally administered during seven days: (T1) non treated control group, (T2) 1 x 10(6), (T3) 2.5 x 10(6) and (T4) 5 x 10(6). Three lambs, infected with H. contortus, were used per group. Faeces were obtained from the rectum of each lamb during the fungal administration period (days 0-6) and for six days after that period. Four coproculture replicates were made from each animal in days 2, 4, 6, 8 and 10. A higher chlamydospore dose produced higher CPG in faeces (p < 0.05), but a clear dose dependent effect was not found either in the larvae reduction or in the CPG:EPG ratio. When ratios were re-analyzed, independently of the treatment groups of origin, a better efficacy was obtained with a ratio from 5 to 10 CPG:EPG and a higher ratio (> 10 per egg) showed a lower reduction efficacy (p < 0.05). The binomial analysis showed that for each unit of increment in CPG:EPG ratio there was a reduction of larvae number until a point (between 5 and 10 CPG:EPG) where no further reduction was detected. The surface response test indicated that the number of larvae was reduced by CPG until possible saturation. The highest CPG:EPG ratios did not necessarily improve efficacy of D. flagrans.

A technique for the quantification of Duddingtonia flagrans chlamydospores in sheep faeces

Previous observations showed that Duddingtonia flagrans chlamydospores were visualized in McMaster chambers containing faeces of treated sheep. This trial explored the McMaster technique as a tool to quantify chlamydospores in sheep faeces. A range of individual chlamydospore doses (from 19.5 x 10(6) to 177.5 x 10(6)) were offered orally to nine lambs for 7 consecutive days. A faecal sample (5 g) was daily obtained from the rectum of each animal (from days 1 to 13) to perform the McMaster technique using a sugar flotation fluid with 1.27 g/mL density. Each chlamydospore counted in the McMaster chamber was considered as 50 chlamydospores per g of faeces (CPG). The results confirmed that the estimated CPG was associated with the daily dose offered to the animals (r(2)=0.90; P<0.001). Furthermore, the total chlamydospore dose received by each animal was strongly associated to the total quantity of CPG obtained from the bulk faeces (TCtot) (r(2)=0.96; P<0.0001). Quantification of CPG can be used as a helpful tool to determine the number of chlamydospores reaching the faeces in orally dosed animals. This could be used to evaluate the efficacy of D. flagrans for the control of gastrointestinal nematode larvae in sheep faeces.

Digestibility of Duddingtonia flagrans chlamydospores in ruminants: in vitro and in vivo studies

BackgroundThe use of Duddingtonia flagrans as a tool for the biological control of gastrointestinal nematodes (GIN) is a promising alternative to anthelmintics. The chlamydospores of D. flagrans are orally dosed and their thick cell wall gives them the capacity to resist digestion and pass through the gastrointestinal tract (GIT). Chlamydospores reaching the faeces are able to germinate and trap nematode larvae. The efficacy of this control method is based on reducing the numbers of infective larvae leaving the faeces. Techniques have recently been developed for quantifying the numbers of chlamydospores in faeces. As the number of non-digested spores could be relevant in the design and optimization of dosing programmes for the control of GIN infective larvae, the aim of the present study was to estimate the loss of D. flagrans chlamydospores during their passage through the ruminant gastrointestinal tract using in vitro and in vivo techniques.ResultsAfter in vitro rumen digestion, chlamydospore recovery was not different from the quantity originally incubated (undigested spores) (P > 0.05). In vitro rumen+abomasum digestion caused nearly 36% loss of the chlamydospores originally incubated (P < 0.05). Germination of chlamydospores classified as viable was 24.3%. Chlamydospores classified as non-viable did not germinate. Rumen digestion resulted in more spore germination (R1 = 35.7% and R2 = 53.3%) compared to no digestion (time 0 h = 8.7%). Subsequent abomasal digestion reduced germination (R1+A = 25%) or stopped it (R2+A = 0%). In vivo apparent chlamydospore digestibility in sheep showed a loss of 89.7% of the chlamydospores (P < 0.05).ConclusionsThe loss of chlamydospores was evident under in vitro and in vivo conditions. Negligible amounts of spores were lost during the in vitro rumen digestion. However, in vitro rumen+abomasum digestion resulted in a chlamydospore loss of approximately 36%. In vivo passage through the sheep GIT resulted in a total loss of 89.7% of the orally administered spores.

Potential of condensed tannins for the reduction of emissions of enteric methane and their effect on ruminant productivity

El metano (CH4) es un gas subproducto de la fermentacion de los carbohidratos en el rumen. La agricultura contribuye con el 47% de las emisiones antropogenicas de CH4, siendo los rumiantes responsables del 39% de las emisiones de metano enterico. Este gas de efecto invernadero (GEI) tiene un potencial de calentamiento global 25 veces mas que el CO2 y representa una perdida de hasta el 12% de la energia total consumida por los rumiantes. Este trabajo describe los mecanismos de accion de los taninos condensados contenidos en follajes y frutos y su efecto en los microbios del rumen, asi como su potencial en la mitigacion de las emisiones de CH4. Los hallazgos sugieren que los taninos condensados reducen la poblacion de protozoos hasta 79%, reduciendo ademas los metanogenos del rumen hasta en 33%. Los taninos condensados se unen a proteinas y polisacaridos formando complejos, reduciendo asi la digestibilidad de la meteria seca y organica y la produccion de H2 metabolico, el que es usado por metanogenos para la reduccion del CO2 a CH4. Estudios in vitro sugieren que los taninos condensados pueden reducir el CH4 en el rumen hasta 63%, mientras que in vivo se han registrado reducciones hasta 58% en la produccion de CH4. Ademas, la incorporacion de taninos condensados en la racion de rumiantes tiene el potencial de aumentar la ganancia de peso en 26%, relacionando esto al aumento en el flujo de proteina de baja degradacion ruminal al intestino delgado o la reduccion de la energia perdida en forma de CH4 en el rumen. Se concluye que la incorporacion de taninos condensados en la racion de los rumiantes en concentracion de 3-6% de materia seca puede reducir las emisiones de CH4 asi como mejorar la ganancia de peso y produccion de leche de los animales productivos.

Milk production and reproduction of dual-purpose cows with a restricted concentrate allowance and access to an association of Leucaena leucocephala and Cynodon nlemfuensis

The aim of the study was to evaluate the productive and reproductive performance of dual-purpose (DP) cows with a restricted concentrate allowance and access to a forage association of Leucaena (Leucaena leucocephala) and Stargrass (Cynodon nlemfuensis). Twenty-four multiparous Holstein × Zebu cows were used during the first 98 days postpartum. Treatments were control (CT): nightly grazing of Stargrass + commercial concentrate (3.97 kg dry matter [DM]/d), and Leucaena (LT): nightly grazing of Stargrass + commercial concentrate (1.97 kg DM/d) + 4 h grazing on an association of Leucaena/Stargrass. The actual time spent browsing Leucaena represented 38% of the total time of consumption. The bite rate of Leucaena was 22 5 bites/min with a bite size of 0.541 ± 0.08 g DM. The estimated intake of Leucaena per cow was 503 ± 228 g DM/d. Milk yield per cow was similar (P > 0.05) between treatments (CT = 12.28 ± 0.6 kg/d, LT = 11.97 ± 0.6, TL = 11.9 0.6) with a similar composition (P > 0.05). There were no differences (P > 0.05) between treatments for changes in live weight (CT −29.6 kg, LT −33.3 kg) and body condition (CT −1.3, LT −1.4, in a 1–9 scale). Population of ovarian follicles per cow was similar between treatments throughout the experiment. Pregnancy rate was 33% for CT and 25% for LT, with no significant differences (P > 0.05). Grazing an association of Leucaena and Stargrass can replace part of the concentrate without detrimental effects on production and reproduction in DP cows.

Effect of supplementation with saponins from Yucca schidigera on ruminal methane production by Pelibuey sheep fed Pennisetum purpureum grass

The aim of the work was to determine the effect of increasing concentrations of saponins from Yucca schidigera in the diet on voluntary intake, rumen fermentation and methane (CH4) production in Pelibuey sheep fed a tropical grass Pennisetum purpureum. Five male sheep (32.2 ± 1.1 kg liveweight) were fed chopped P. purpureum grass in a 5 × 5 Latin square design. Sheep were supplemented with 0.0, 1.5, 3.0, 4.5 or 6.0 g per day of saponins from Y. schidigera mixed with ground corn, before the grass was offered. Feed intake, feed refusal and total faecal output were recorded for 20 days of the adaptation period and 5 days of the experimental period. Apparent digestibility of dry matter (DMD), organic matter (OMD), neutral detergent fibre (NDFD) and acid detergent fibre (ADFD) were determined. Ruminal methane emission was estimated using stoichiometric balance and the molar proportion of volatile fatty acids was determined by gas chromatography. Voluntary intake, DMD, OMD, NDFD, ADFD, volatile fatty acids and CH4 emission were not affected (P > 0.05) by increasing inclusion levels of saponins in the ration of sheep. Nonetheless, CH4 production increased as the voluntary intake of NDF augmented. Addition of 6 g of saponins per day as a supplement to Pelibuey sheep fed a tropical grass did not affect voluntary intake and digestibility of DM, OM, NDF and ADF, or ruminal methane production.

Effect of condensed tannins from Leucaena leucocephala on rumen fermentation, methane production and population of rumen protozoa in heifers fed low-quality forage

Objective The aim of the experiment was to assess the effect of increasing amounts of Leucaena leucocephala forage on dry matter intake (DMI), organic matter intake (OMI), enteric methane production, rumen fermentation pattern and protozoa population in cattle fed Pennisetum purpureum and housed in respiration chambers. Methods Five crossbred heifers (Bos taurus×Bos indicus) (BW: 295±6 kg) were fed chopped P. purpureum grass and increasing levels of L. leucocephala (0%, 20%, 40%, 60%, and 80% of dry matter [DM]) in a 5×5 Latin square design. Results The voluntary intake and methane production were measured for 23 h per day in respiration chambers; molar proportions of volatile fatty acids (VFAs) were determined at 6 h postprandial period. Molar concentration of VFAs in rumen liquor were similar (p>0.05) between treatments. However, methane production decreased linearly (p<0.005), recording a maximum reduction of up to ~61% with 80% of DM incorporation of L. leucocephala in the ration and no changes (p>0.05) in rumen protozoa population were found. Conclusion Inclusion of 80% of L. leucocephala in the diet of heifers fed low-quality tropical forages has the capacity to reduce up to 61.3% enteric methane emission without affecting DMI, OMI, and protozoa population in rumen liquor.

Effect of metabolizable energy intake on energy partitioning into muscle and fat in Pelibuey ewes

In ruminants, seasonality and physiological conditions result in fluctuations in feed intake, inducing periods of underfeeding and refeeding throughout the year. These seasonal variations induce fluctuations in live weight in grazing animals (Atti et al., 2000; Mahouachi and Atti, 2005; Kamalzadeh et al., 2009), and consequently in the energy content of the carcass and the whole body. Nonetheless, in hair sheep breeds there is scarce information relative to carcass composition and energy changes in the carcass during periods of weight loss and gain. Moreover, it has been reported that knowledge of body composition of productive animals is of relevance in order to better assess nutrient requirements. The aim of the present work was to evaluate the effect of metabolizable energy intake (MEI) on energy partitioning of muscular and adipose tissues in adult Pelibuey ewes.