Two experiments were carried out to evaluate the bactericidal impacts of Bacillus amyloliquefaciens CECT 5940 on the shedding of faecal pathogenic bacteria in dairy calves (Experiment 1) and in adults dogs (experiment 2). In the calves experiment, a completely randomized design was used to investigate the faecal bacteria profile of Holstein dairy calves fed with either pasteurized waste milk (PWM; n = 9) or a formulated non-medicated milk replacer (NMR; n = 9) for 60 d. The NMR containing sodium-butyrate and the active probiotic B. amyloliquefaciens CECT 5940. In the dogs experiment, addition of same probiotic (i.e., B. amyloliquefaciens CECT 5940) was carried out in two stages. The first stage started from day 7-37, and the second from day 44-71. The assessment of faecal score measured on day 22, 37, 42, 57, 71 and 77 to determine the texture of the stools. Calves received PWM consumed (P < 0.05) more starter feed between day 16 and day 45. The calves fed NMR had more moisture faeces and less cough reflux than the PWM-calves. Feeding NMR to calves increased faecal Klebsiella oxytoca and Proteus vulgaris counts in comparison to PWM-calves. The administration of B. amyloliquefaciens CECT 5940 to the dog diet has no significant effect on the hardness of the stool. Meanwhile, the bacillus count increases while the coliforms count decreases upon B. amyloliquefaciens CECT 5940 administration. This reveals that B. amyloliquefaciens CECT 5940 survived the gastrointestinal passage and rapidly colonized the dog intestine, which could positively affect the metabolism and composition of the intestinal microflora. These results show that B. amyloliquefaciens are a promising probiotic with an antimicrobial and bactericidal activities against the intestinal pathogenic bacteria for dairy calves and adult dogs.

In production systems of prickly pear fruit and prickly pear cactus, significant amounts of pruned material, which could be used as an ingredient in animal feeding, is generated. The aim of this study was to measure the nutrient content, fermentation kinetics and in vitro digestibility of eleven cultivars of cladodes of prickly pear cactus. The fermentation was measured indirectly using the gas production technique, where 500 mg of DM substrate (prickly pear cactus cultivars) were placed in amber glass flasks of 125 mL with 90 mL of ruminal inoculum under a continuous flow of CO 2 . Flasks were hermetically wrapped up with a rubber stopper and a metal ring, and were placed in a water bath at 39°C. The fermentation gas pressure was measured using a monometer at 0, 2, 4, 6, 8, 12, 16, 20, 24, 32, 38, 50 and 72 h incubation. Results show that the chemical composition ranged between (g kg -1 DM): 64 and 160 g kg -1 dry matter (DM), 137-293 g kg -1 DM ash, 52-101 g kg -1 DM crude protein, 3-22 g kg -1 DM ether extract, 251-393 neutral detergent fiber and 132-192 acid detergent fiber. The gas volume was different (p \ 0.05) among cultivars, with the Red Vigor cultivar having the largest volume at 378 mL g -1 DM. The highest volume of gas was produced during the first 24 h in on average 67 % of the total produced. The in vitro DM digestibility displayed values of up to 82 % in the Roja Pelota cultivar. It can be concluded that the cladodes of prickly pear cactus from different cultivars can be used in animal feed for its good rumen fermentation characteristics.

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The objective of the present research was to evaluate the nutritive value and the fermentationcharacteristics of cactus pear silages and diets including them for growing lambs. There weretwo cactus pear silage types: one made from cladodes and the other combining cladodes andcactus pear fruit. Similarly, it was calculated the gas potential emission index (GPEI; dL lamb-1day-1). The four diets: control (with not silage, NSD), including corn silage (CSD), or cladodecactus pear silage (CCSD), or cladode-fruit cactus pear silage (CFSD) were iso-nitrogenous(15% CP) and iso-energetic (2.7 Mcal of ME kg-1 of dry matter) fulfilling the requirements forfinishing lambs. Eight commercial cross lambs (23±3.0 kg liveweight) were used, under a 4 x 4replicated Latin Square design. The results indicated that the CCSD and CFSD had 3% more(P<0.05) dry matter (DM) content than the CSD, but the later had more (P<0.05) protein (80 gkg-1) and greater digestibility (60%) than the CCSD and CFSD (50 g kg-1 and 50%). The dietswith CCSD and CFSD had more (P<0.05) crude protein (160 g kg-1) than the control and CSD(150 g kg-1 DM). The in vitro digestibility of the control diet was greater (P<0.05) than the otherdiets, although the DM voluntary intake, apparent digestibility, and the acid detergent fiber(ADF) were not different (P>0.05). The neutral detergent fiber (NDF) was greater (P<0.05) indiets including silages in comparison to the control diet. Lambs fed with control or CCSD dietshad a gas potential production of 350 and 370 L lamb-1 d-1, in comparison to 200 and 210 Llamb-1 d-1 from CSD and CFSD diets. It is concluded that the nutritive and in vitro fermentativequalities of the CCS and CFS were similar to CS, thus, their inclusion in diets for finishing lambscan be considered as a feeding alternative, and more importantly, CFS could mitigate theemission of greenhouse gases.

Vegetable oils have been shown to reduce enteric methane (CH4) production by up to 20%. However, when the level of incorporation exceeds the threshold of 70 g/kg DM, dry matter intake (DMI) and nutrient digestibility may be reduced. The objective of this study was to determine the effects of the incorporation of three levels of palm oil (PO) on enteric CH4 emissions, rumen fermentation and apparent digestibility in heifers fed low-quality grass. Four rumen-cannulated heifers (Bos taurus × Bos indicus) were randomly assigned to four treatments: control (CON) and three increasing PO levels: 20, 40 and 60 g/kg in a 4 × 4 Latin square design with four periods of 22 days (14 days of adaptation to the ration), 5 days of feces and rumen fluid sampling (day 18, 4 h postprandial) and the last 3 days for measurements of CH4 in respiration chambers. With the exception of CP (p = 0.04), starch (p = 0.002) and EE (p < 0.001), the intake of nutrients was not affected by the inclusion of PO (p > 0.05). The apparent digestibility (AD) of nutrients was not affected by the inclusion of PO (p > 0.05), except for starch, which reduced its AD as the PO level was increased (p < 0.05). The gross energy intake was higher in PO-containing rations (p = 0.001), on the other hand, the digestible energy intake was similar between treatments (p > 0.05). In situ ruminal digestion kinetics and the potential degradability remained unchanged (p > 0.05), however, the effective degradability decreased with the inclusion of PO in the rations (p < 0.05). The ruminal pH and molar proportions of acetic, isovaleric and valeric acid were not different between treatments (p > 0.05). The ruminal concentration of propionic acid increased as the PO level increased, reaching its highest molar proportion with 60 g/kg PO (p < 0.05), however, the acetic/propionic ratio and the molar proportions of butyric acid and isobutyric acid decreased as the PO level increased (p < 0.05). The total daily CH4 production was lower in diets containing 20, 40 and 60 g/kg PO compared to the CON diet (p < 0.001). The production of CH4 per kg DMI and DOMI was greater (p < 0.05) for the CON diet compared to all three rations containing PO. The emission intensity, Ym, energy lost as CH4, emission factor (EF) and kg CO2 eq/year were reduced as an effect of the inclusion of PO (p < 0.05). Based on the results obtained, it is concluded that the incorporation of PO in cattle rations has the potential to reduce enteric methane emissions by 4% for every 10 g/kg PO in the ration, without affecting DMI, apparent digestibility or the consumption of digestible nutrient fractions.

Guanidinoacetic acid (GAA) is a feed additive that promotes growth in animals, while maize (Zea mays L.) is used for the mitigation of ruminal greenhouse gases. However, it is unknown if GAA affects the efficiency of maize in mitigating gases or if there is synergy between them. Therefore, the objective of this study was to evaluate the in vitro production of total gas, methane (CH4), carbon monoxide (CO), and hydrogen sulfide (H2S), ruminal fermentation characteristics, and the CH4 conversion efficiency of fresh forage and silage of different genotypes (Amarillo, Montesa, Olotillo, Tampiqueño, and Tuxpeño) of maize, with and without the addition of GAA. The silage of the Amarillo genotype without AAG had the highest (p = 0.01) total gas production rate and the lowest (p = 0.044) delay time before gas production. In addition, at 48 h, the Amarillo silage with GAA increased the production of total gas (p = 0.0001) and CH4, as well as the proportion of CH4 (mL CH4 100 mL−1 total gas). The Amarillo and Tuxpeño genotype produced more (p = 0.033) CO in the first 24 h of incubation, while silage and the addition of GAA only increased (p = 0.001) CO at 6 h. The highest (p = 0.02) H2S production was observed with the ensiled Amarillo genotype with GAA. Regarding fermentation characteristics, the silage of the Amarillo and Montesa genotypes presented the highest degradation of dry matter (DMD), short-chain fatty acids (SCFA), and metabolizable energy (ME), and although there was no effect on CH4 efficiency, the Amarillo and Olotillo genotypes produced more SCFA, ME, and OM per unit of CH4. It can be concluded that rumen gas production, fermentation characteristics, and CH4 conversion efficiency are more influenced by the maize genotype and forage condition than by the addition of guanidinoacetic acid, and of the genotypes evaluated, the forage silage from Amarillo showed the best characteristics and efficiency of CH4.

El objetivo fue caracterizar el crecimiento de aves Criollas Mexicanas (CMX), Hy-Line Brown (HLB) y Rhode Island Red (RIR) mediante los modelos Gompertz-Laird (MNGL), Logístico (MNL), Richards (MNR) y Von Bertalanffy(MNVB). Se utilizaron 70 pollitas de cada genotipo. Cada ave fue identificada para registrar su peso de 7 a 210 d de edad. Los parámetros de los modelos se estimaron con el procedimiento NLIN (algoritmo de Marquardt) de SAS. Se calculó el coeficiente de determinación ajustado, criterio de información de Akaike y criterio de información Bayesiana, para cada caso. La tasa de crecimiento inicial (d−1) en aves CMX fue menor (0.047 15) que en aves RIR (0.071 69) y HLB (0.052 16). Con los cuatro modelos, la tasa de decaimiento en aves CMX fue menor, respecto a los otros genotipos. Asimismo, la edad al máximo crecimiento (d) en las aves CMX,RIR y HLB, varió de 49.4 a 87.9, de 60.7 a 81.6 y de 58.7 a 87.8, respectivamente. Por otro lado, el peso asintótico (g), estimado con los cuatro modelos varió de 2 068.5 a 2 644.3, de 1 902.4 a 2 250.9 y 2 096.3 a 2 464.5, en las aves CMX, RIR y HLB, respectivamente. Con el MNVB se obtuvo el mejor ajuste para los datos de las aves RIR y HLB, en contraste, el MNR fue mejor para las aves CMX, seguido del MNVB. El MNVB sería el más adecuado para el estudio simultáneo del crecimiento de aves CMX, RIR y HLB.