Two assays were conducted to study the Tithonia diversifolia (Td) plant: (1) chemical analysis and in vitro dry matter digestibility (IVDMD) of plant parts and (2) productive performance of lambs fed a traditional diet or a Td diet (30% of Td plus 70% of the traditional diet). The plant parts studied were leaves (L), leaves and petioles (LP); and leaves, petioles and stems (LPS). Feed intake, weight gain and feed conversion were registered weekly during five weeks of experimentation. The L showed higher (P<0.05) crude protein content (26.7%) than LP and LPS (25.5 and 19.7%, respectively). Crude fiber (11.2%), neutral detergent fiber (45.4%), cellulose (16.9%) and hemicellulose (33.5%) were lower in L than in LP (12.5, 46.7, 18.0 and 35.7%, respectively) and LPS (22.6, 59.2, 27.0 and 43.5%, respectively). The L and LP showed the highest IVDMD (89.2 and 88.2%, respectively vs. 77.2% of LPS). The Td diet resulted in greater feed intake and weight gain and lower feed conversion than the traditional diet. Therefore, Tithonia diversifolia is a forage plant of good quality for lambs which does not affect the productive performance.

Mesquite (Prosopis spp.), a highly nutritious legume from arid regions characterized by its secondary metabolites, offers a cost-effective resource to provide energy and protein for small ruminant farmers in harsh environments. In addition, the high concentrations of secondary metabolites found in mesquite pods could be an option to mitigate methane (CH₄) emissions. Thus, the aim of this study was to conduct an analytical review to assess the impact of adding mesquite pods on small ruminant productivity and enteric CH₄ emissions. A comprehensive and structured search of scientific articles resulted in a database of 38 trials. The response variables were evaluated through raw mean differences (RMDs) and standardized mean differences (SMDs), followed by a meta-regression, used to investigate the heterogeneity of the explanatory variables. Supplementation with mesquite pods significantly increased the dry matter intake (DMI) and average daily gain (ADG) and reduced the feed conversion ratio (FCR), with sheep showing the highest effect. The meta-regression demonstrated that the mesquite pod effect was influenced mainly by the species, level of incorporation and processing of the pods. Studies employing in silico CH₄ estimation reported increased emissions when the diets included mesquite pods. In contrast, in vivo studies demonstrated promising results, showing a significant reduction in CH₄ emissions when mesquite pods were included in small ruminant diets. Therefore, future research should focus on evaluating mesquite pod supplementation using precise methods to assess CH₄ emissions.

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, Y_m, 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.

Background and Aim: Weaning is a critical period in calf development, particularly under tropical conditions where nutritional stress and parasitic infestations can precipitate anemia. Anemia compromises growth and survival; yet, few studies have evaluated the effectiveness of hematinic therapy in anemic calves before weaning in tropical systems. This study aimed to assess hematological responses in anemic dairy calves treated with a hematinic complex and to establish anemia thresholds based on hematological indices in healthy calves raised under tropical conditions. Materials and Methods: A total of 22 Holstein × Zebu calves were studied from January to April 2024 in Tabasco, Mexico. Calves were grouped as healthy (n = 10; hematocrit [HCT] >24%) or anemic (n = 12; HCT <24%). The anemic group received an intramuscular hematinic complex for 5 consecutive days and three additional doses at day 42. Hematological parameters were measured every 21 days using an automated analyzer. Anemia thresholds were defined from the healthy group using mean ± 2 standard deviations. Data were analyzed using a repeated-measures design over time. Results: Anemia thresholds were determined as HCT <21.3%, hemoglobin (HGB) <7.5 g/dL, and red blood cell (RBC) <5.4 × 106/μL. At baseline, anemic calves exhibited significantly lower HCT (21.4%), HGB (6.9 g/dL), and RBC (5.9 × 106/μL) compared to healthy controls (p < 0.01). Three calves presented with microcytic hypochromic anemia and one with macrocytic anemia. By day 42, hematinic-treated calves surpassed the anemia threshold, reaching an HCT of 25%, and further increased to 30% following the second treatment. HGB and RBC levels also improved, showing no significant differences from healthy calves at study end. Males responded more robustly to treatment than females. Conclusion: The administration of a hematinic complex effectively restored hematological parameters in anemic calves within 42 days, with sustained improvement following a second application. This intervention is recommended as part of pre-weaning health protocols to mitigate anemia-related growth setbacks in tropical cattle systems. Keywords: anemia, calves, haematocrit, haemoglobin, hematinic complex, red blood cells, tropical cattle systems.

An experiment was carried out to assess the effect of the incorporation of sun-dried foliage of Brosimum alicastrum into rations based on hay of Megathyrsus maximus on intake, rumen fermentation, kinetics of passage, microbial nitrogen supply to the small intestine, apparent digestibility in Pelibuey hair sheep. Four rations were randomly allotted to four rumen-cannulated lambs (BW = 37.4 ± 4.9 kg) using a 4 × 4 Latin square design to assess the effect of increasing levels (0, 15, 30 and 45% DM basis) of foliage of Brosimum alicastrum on a basal ration of M. maximus. Organic matter intake and water consumption increased linearly (p < 0.01) with increasing levels of B. alicastrum in the ration. The rate and potential extent of rumen fermentation of OM and CP of B. alicastrum were 10.6%/h and 86.6% and 11.4%/h and 95.2%, respectively, but no effect (p > 0.05) was found on the potential rumen degradation of DM (40.2%) or on the rate of degradation of DM (0.033%/h) of M. maximus, although a positive effect was found in the rumen degradation rate of NDF (p < 0.05). VFA and ammonia concentration in the rumen and the rate of passage of solids and liquids through the rumen (k₁) increased linearly (p < 0.01) with increasing levels of B. alicastrum. Rumen pH was not affected by the incorporation of B. alicastrum (p > 0.05). Microbial nitrogen supply to the small intestine (p < 0.001), apparent digestibility of dry matter (p < 0.01) and NDF (p < 0.05) of the rations were also significantly increased as a result of the incorporation of B. alicastrum foliage. Results from this experiment suggest that the foliage of Brosimum alicastrum can be readily incorporated at around 30% of the ration of dry matter in hair sheep with beneficial effects on feed intake, rate of passage and microbial N supply to the lower tract.