Circadian rhythm of salivary and serum urea concentration in alpacas and sheep receiving diets with different levels of protein.

All vertebrates possess a daily rhythm, encompassing a comprehensive set of physiological, cognitive, and behavioral patterns that manifest throughout a 24-hour period. The aim of this study was to compare the effect of crude protein (CP) levels in the diet on the daily rhythm of urea in serum (US) and saliva in alpacas and sheep. Ten alpacas and ten sheep, adult, clinically healthy males, were used; they were maintained in natural light conditions and fed ad libitum with two levels of CP (16 and 7%). Blood and saliva samples were taken every 4 h for 48 h. A two-way ANOVA was conducted to analyze the parameters, including adjusted mean rhythm (MESOR), amplitude, and acrophase. It was found that both US and saliva urea exhibited circadian rhythms with a peak during the midday (10:59 - 12:16 h). The MESOR with low CP diets was higher (P < 0.05) in alpacas. The MESOR of urea levels in saliva was greater (P < 0.05) at the highest level of CP in the diet, with no differences between alpacas and sheep (P > 0.05). The amplitude was greater (P < 0.05) in alpacas and at the high level of CP compared to the low level of CP in the diet. Our findings reveal that both serum and saliva urea levels in alpacas and sheep follow a daily rhythm and the MESOR of US was higher in alpacas when they consume food with low CP content, and this difference disappears when CP levels are increased in the diet.

Relationship between Chemical Composition and In Vitro Methane Production of High Andean Grasses.

The present study aims to establish the relationship between chemical composition and in vitro methane (CH4) production of high Andean grasses. For this purpose, eight species were collected in dry and rainy seasons: Alchemilla pinnata, Distichia muscoides, Carex ecuadorica, Hipochoeris taraxacoides, Mulhenbergia fastigiata, Mulhenbergia peruviana, Stipa brachiphylla and Stipa mucronata. They were chemically analyzed and incubated under an in vitro system. Species such as A. pinnata and H. taraxacoides were characterized by high crude protein (CP. 124 g/kg DM) and low neutral detergent fiber (NDF. 293 g/kg DM) contents in both seasons, contrary to Stipa grasses. This same pattern was obtained for H. taraxacoides, which presented the highest values of gas production, organic matter digestibility (DOM), metabolizable energy (ME) and CH4 production (241 mL/g DM, 59% DOM, 8.4 MJ ME/kg DM and 37.7 mL CH4/g DM, on average). For most species, the content of CP, acid detergent fiber (FDA) and ME was higher in the rainy season than in the dry season, which was the opposite for CH4 production (p ≥ 0.05). In general, the nutritional content that most explained the behavior of CH4 production was the NDF content (R2 = 0.69). Grasses characterized by high NDF content produced less CH4 (R = -0.85).

Role of Secondary Plant Metabolites on Enteric Methane Mitigation in Ruminants.

The rumen microbiome plays a fundamental role in all ruminant species, it is involved in health, nutrient utilization, detoxification, and methane emissions. Methane is a greenhouse gas which is eructated in large volumes by ruminants grazing extensive grasslands in the tropical regions of the world. Enteric methane is the largest contributor to the emissions of greenhouse gases originating from animal agriculture. A large variety of plants containing secondary metabolites [essential oils (terpenoids), tannins, saponins, and flavonoids] have been evaluated as cattle feedstuffs and changes in volatile fatty acid proportions and methane synthesis in the rumen have been assessed. Alterations to the rumen microbiome may lead to changes in diversity, composition, and structure of the methanogen community. Legumes containing condensed tannins such as Leucaena leucocephala have shown a good methane mitigating effect when fed at levels of up to 30-35% of ration dry matter in cattle as a result of the effect of condensed tannins on rumen bacteria and methanogens. It has been shown that saponins disrupt the membrane of rumen protozoa, thus decreasing the numbers of both protozoa and methanogenic archaea. Trials carried out with cattle housed in respiration chambers have demonstrated the enteric methane mitigation effect in cattle and sheep of tropical legumes such as Enterolobium cyclocarpum and Samanea saman which contain saponins. Essential oils are volatile constituents of terpenoid or non-terpenoid origin which impair energy metabolism of archaea and have shown reductions of up to 26% in enteric methane emissions in ruminants. There is emerging evidence showing the potential of flavonoids as methane mitigating compounds, but more work is required in vivo to confirm preliminary findings. From the information hereby presented, it is clear that plant secondary metabolites can be a rational approach to modulate the rumen microbiome and modify its function, some species of rumen microbes improve protein and fiber degradation and reduce feed energy loss as methane in ruminants fed tropical plant species.

Determination of Aflatoxin M1 in Raw Milk from Different Provinces of Ecuador.

Aflatoxin M1 (AFM1) is a mycotoxin from Aspergillus flavus and A. parasiticus, classified as carcinogenic and hepatotoxic. The objective of the present investigation was to determine its presence in raw milk from north-central Ecuador, constituted by the provinces of Pichincha, Manabí, and Santo Domingo de los Tsáchilas. These areas represent approximately 30% of Ecuadorian milk production. By the end of the investigation, a total of 209 raw milk samples were collected, obtained both during the dry (June and August) and rainy seasons (April and November) of 2019. AFM1 concentrations were measured with lateral flow immunochromatographic assays, and 100% of the samples were positive for this mycotoxin, presenting a mean value of 0.0774 µg/kg with a range of 0.023 to 0.751 µg/kg. These AFM1 levels exceeded the European Union regulatory limit of 0.05 µg/kg in 59.3% (124/209) of samples, while only 1.9% (4/209) exceeded the Ecuadorian legal limit of 0.5 µg/kg. By using non-parametric tests, significant differences were determined (p ≤ 0.05) between the provinces for months of study, climatic season (being higher in the dry season), and climatic region (greater in the coast region). On the other hand, there were no significant differences (p ≥ 0.05) between the types of producers or between production systems. Therefore, AFM1 contamination in raw milk does not present a serious public health problem in Ecuador, but a monitoring and surveillance program for this mycotoxin in milk should be developed to prevent consumer health problems.

Contenido de yodo en leche de vacuno procedente de la sierra y costa del Perú / Iodine content of cattle milk from two milksheds in Perú

Con la finalidad de establecer la relación causa-efecto entre área geológica y contenido de yodo en la leche de vacuno y estimar la contribución del consumo de leche a la ingesta de yodo, en la presente investigación se ha determinado el contenido de yodo en leche de vacuno procedente de la sierra y costa de Perú. Se obtuvieron muestras de leche de tres principales zonas productoras, 62 en Cajamarca, 44 en Arequipa, ambos departamentos de la Sierra, y 27 muestras en el Departamento de Lima en la Costa. La determinación cuantitativa de yodo se realizó por el método de Zak modificado, basado en la relación de Sandell-Kolthoff. Las medianas obtenidas fueron 24 µg/L en Cajamarca, 34 µg/L en Arequipa y 170 µg/L en Lima. El valor de la mediana corespondiente a la sierra, 26 µg/L, fue significativamente más baja que el corespondiente a la Costa; además mientras en la primera el 81 por ciento de los valores individuales estuvieron por debajo de 50 µg/L, en la segunda, contrariante, el 77 por ciento estuvieron sobre 80 µg/L. Estos resultados confirman que el contenido de yodo en leche de la sierra es 6 veces menor que en la costa y que su consumo contribuye significativamente a satisfacer las necesidades fisiológicas de yodo de los pobladores de dicha zona

[Iodine content of cattle milk from mountain and coast from Perú]. / Contenido de yodo en leche de vacuno procedente de la Sierra y Costa del Perú.

With the objective to establish the cause-effect relationship between a geological area and the iodine content in cattle milk, and to estimate the contribution of milk consumption to the dietary iodine intake, the iodine content in cattle milk from the sierra and the coastal regions of Perú was determined. Milk samples were collected of cows from the three main productive zones of Perú, 62 in Cajamarca, 42 in Arequipa, both in the sierra, and 27 in Lima at the coast. The measurement of iodine was made by the method of Zak, based on the Sandell- Kolthoff reaction. The median values obtained were 24 microg/L in Cajamarca, 34 microg/L in Arequipa, and 170 microg/L in Lima. The median value in the sierra, 26 microg/L, was significantly lower than the one found in the coast. Moreover, while in the former 81% of individual values were below 50 microg/L, in the latter, on the contrary, 77% were above 80 microg/L. These results confirm that the iodine content in cattle milk is related to ecological factors. At the same time, they demonstrate that the iodine content in milk from the sierra is six times lower than in milk from the coast, and also that its consumption does not contribute significantly to satisfy the human physiological requirements of iodine in that zone.