Objective: to evaluate the effects of organic copper (Cu) and selenium (Se) on milk production, milk quality and reproductive parameters of Normande dairy cows. Materials and methods: 36 multiparous cows (BW = 600 ± 32 kg) were used, distributed in completely randomized blocks. Treatments were: T0: without mineral supplementation, T1: inorganic mineral supplementation with Cu and Se, T2: 50% Inorganic supplementation + 50% organic supplementation, with an experimental period of 150 days (30 days before calving and 120 days of lactation). The variables evaluated were milk production and quality (total solids, proteins, fat, somatic cells and MUN), blood metabolites (glucose, betahydroxybutyrate and BUN) and reproductive parameters (open days, days to first service and services per conception). Results: No differences were observed in milk production and quality (P> 0.05). However, open days and services per conception were shorter when cows were supplemented with organic minerals (P <0.05). Conclusions: In this study milk production, milk quality and blood metabolites were not affected by supplementation with Se and Cu. However, the reproductive parameters of the cows improved when supplemented with organic Se and Cu.

Extensive livestock management is a common practice in the dry tropics. However, summer conditions can cause high fiber and low protein concentrations, even in grasses adapted to tropical soils, such as Angleton (Dichanthium spp.), widely used in producing small ruminants. On the other hand, Guacimo (Guazuma ulmifolia) is a tree that overcomes high temperatures and hydric stress. This research evaluated the effect of replacing Angleton with four foliage levels of Guacimo on hair lambs’ intake, digestibility, and blood metabolites. Twelve male hair lambs with an average of 22.0 ± 1.3 kg of body weight were used in an experimental 4 × 4 square design. Treatments were as follows: 100 % Angleton hay; 85 % Angleton hay + 15 % Guacimo foliage; 70 % Angleton hay + 30 % Guacimo foliage, and 55 % Angleton hay + 45 % Guacimo foliage. Dry matter (DM), organic matter (OM), crude protein (CP), and neutral detergent fiber (NDF) intake, as well as CP digestibility and glucose concentrations, increased linearly as the level of Guacimo rose (P > 0.05). Guacimo foliage improves intake, blood metabolites, and in vivo digestibility of DM and can be used to replace part of the hay in lamb rations.

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The aim was to evaluate the fatty acid profile of meat of crossbred cattle grazing under different supplementation strategies. Thirty crossbred steers (1/2 Holstein x 1/2 Zebu) were used in a completely randomized design with three groups of different supplementation strategies (SS) according to the climatic season of the year: SS-1 (mineral salt/mineral salt with urea), SS-2 (mineral salt with urea/protein supplement 0.1% PC), and SS-3 (protein supplement 0.1% BW / 0.2% BW protein supplement). Longissimus dorsi muscle samples were collected, stored, and frozen until analysis of the fatty acid (FA) profile. Data were subjected to analysis of variance (ANOVA), using the Tukey test (P < 0.5) (SAS 2008). Our results exhibited that the oleic acid (C18: 1n9cis) was affected by supplementation strategies, the oleic acid was higher (34.91%) in SS-1. In addition, the content Polyunsaturated fatty acids (PUFA; P <0.05); C18: 3n3 (α – linolenic), C18: 2c9t11 (Rumenic / CLA), C18: 2t10c12 (Trans-10, cis-12-octadecadienic / CLA) and C20: 5n3 (eicosapentaenoic - EPA) also were higher in SS-1. In contrast, in SS-3 the C20: 4n6 (arachidonic) was higher (1.09%). The total PUFA content was influenced (P <0.05), with a higher content in the SS-1 group (3.58%). SS-3 influenced higher levels of AG n-6 (1.86%), and AG n-3 (1.02%) being higher in SS-1, producing a lower n-6: n-3 ratio in SS-1 (P <0.05) of 1.57. Grazing animals with mineral supplementation SS-1 showed meat with a higher composition of polyunsaturated fatty acids, mainly omega-3 and CLA, which provided a reduction in the n-6: n-3 ratio, highly related to human health.

The objective of this study was to evaluate the effects of different energy sources on performance, and carcass characteristics in hair lambs finished in feedlots. Twenty-eight hair lambs with an initial body weight (BW) 20.8 ± 3.01, were randomly assigned to one of four dietary treatments included with seven lambs per treatment. The dietary treatments included an energy source included at 18% Dry matter: S. spectabilis flour (SF), palm kernel (PK), corn bran (CB) and rice bran (RB) in a diet based in corn silage, ground corn, soybean meal formulated to 13.0% PC and 2.6 Mcal/Kg of DM. The feeding trial was performed for 13 weeks. Water was allowed ad libitum. Animals were slaughtered after the feeding trial, and the carcasses were kept at 4°C for 24 h under Colombian standard guidelines. Data were analyzed by using the ANOVA procedure, SAS version 9.1 to perform a randomized complete experiment with four diets. For each studied variable, the mean and standard error of the mean (SEM) were calculated and differences between means were evaluated Using Tukey′s Test (P ≤ 0.05). Final body weight, hot carcass weight, cold carcass weight, hot dressing carcass (%), and cold dressing weight (%) were not different between the four treatments (P &gt; 0.05). Dry matter intake was superior to the S. spectabilis flour (P &lt; 0,001). Feed efficiency was higher in the CB and RB treatments (P &lt; 0,05). These results indicate that the inclusion of S. spectabilis and palm kernel could improve the dry matter intake and corn bran and rice bran the feed efficiency without effects on carcass characteristics