Carlos F. Aguilar-Pérez

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 Fatty Acids on Reproductive Performance of Ruminants

Different types of fats have been utilized in an attempt to improve reproductive function in ruminant animals. Fatty acids derived from plants and oil seeds have exerted a major impact on reproductive performance, some of the most common sources include sunflower, linseed, cottonseed, rapeseed and soyabean. Animal fat (tallow) and calcium salts of saturated fatty acids may escape in a significant percentage rumen hydrogenation to be incorporated into adipose tissue and milk. Fish by-products contain a high proportion of polyunsaturated fatty acids (PUFAs) and pass without being altered in the rumen exerting no effects on rumen fermentation. Each dietary source of fat varies regarding composition of specific fatty acids (Table 1). Early studies of the effect of fat in the ration on reproductive performance were carried out by Burr & Burr (1930), who observed that fat deficiency in the ration of growing rats induced alterations in ovulation rate and on the onset of oestrus, while lipid supplementation reestablished reproductive performance of the females, coining the concept of essential fatty acids. In later studies, research was aimed at evaluating the effect of fat supplementation in different animal species both ruminant and non-ruminant, on reproductive aspects such as the establishment of puberty (Smith et al., 1989), semen production (Castellano et al., 2010), maternal recognition of pregnancy (Abayasekara & Wathes, 1999, Filley et al., 2000, Lopes et al., 2009) by means of the suppression of luteolytic signals (Mattos et al., 2000), restart of ovarian activity after parturition (de Fries et al., 1998), follicle development, quality of oocytes (Staples & Thatcher, 2005; Bilby et al., 2006c), and of the embryo (Cerri et al., 2009), modification in the mechanism of synthesis and secretion of hormones involved in reproductive processes (Staples et al., 1998) and on production aspects such as quality of milk (Rego et al., 2004; Bernal et al., 2010) or meat (Wood et al., 2003). Due to the fact that some fatty acids (FA) are essential for mammals and to the role of fatty acids on reproductive processes, it is possible that cattle reproduction will be influenced more by the type of lipids consumed than for the total lipid intake. This is particularly important since ruminants hydrogenate PUFAs in the rumen, limiting the amount of PUFAs that are absorbed from the small intestine (Thatcher & Staples, 2007,

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.