Resumen Introducción. La oferta de ensilaje de pasto Kikuyo permite reducir la estacionalidad de la producción láctea, pero es necesario evaluar los factores que afectan el proceso de ensilado para mantener una calidad similar a la del forraje fresco. Objetivo. Evaluar el efecto de la edad de rebrote, el tamaño del picado, el tiempo de oreo con el uso de aditivos sobre la calidad del ensilaje de pasto Kikuyo. Materiales y métodos. El estudio se realizó en Mosquera, Colombia, durante el 2020. Se evaluó el efecto de la edad de rebrote (28, 42 y 70 días), el tamaño de picado (1,5 cm, 3,0 cm y planta completa), tiempo de oreo (0 y 6 horas) y uso de aditivos (glicerina cruda y bacterias ácido lácticas (BAL)) sobre los parámetros: composición química, digestibilidad in situ de la materia seca (DISMS), dinámica del pH, perfil de ácidos grasos volátiles (AGV's), pérdidas de materia seca y calidad organoléptica. La información se analizó con un diseño completamente al azar con arreglo factorial. Resultados. El uso de pasto Kikuyo de 70 días de rebrote redujo (p<0,05) la proteína cruda, la digestibilidad y la energía, y aumentó la pared celular y la materia seca (MS) del ensilaje. La utilización de aditivos redujo (p<0,05) el pH final del pasto maduro. El picado pequeño o la inclusión de glicerina cruda en la planta completa incrementaron (p<0,05) la DISMS. El uso de aditivos redujo (p<0,05) el pH final del ensilaje elaborado con la planta completa. El oreo previo al empaque incrementó (p<0,05) la MS y (p<0,05) el pH final, pero redujo (p<0,05) la proteína cruda y el ácido láctico. Conclusión. El uso de forrajes tiernos, el picado pequeño y el embolsado en fresco mejoraron la calidad del ensilaje de pasto Kikuyo. El uso de forrajes maduros requiere aplicación de aditivos.

Abstract Introduction. The availability of Kikuyu grass silage helps reduce the seasonality of dairy production, but it is necessary to evaluate the factors affecting the ensiling process to maintain a quality similar to that of fresh forage. Objective. To evaluate the effect of regrowth age, chop size, wilting time with the use of additives on the quality of Kikuyu grass silage. Materials and methods. The study was conducted in Mosquera, Colombia, during 2020. The effect of regrowth age (28, 42, and 70 days), chop size (1.5 cm, 3.0 cm and whole plant), wilting time (0 and 6 hours), and the use of additives (crude glycerin and lactic acid bacteria (LAB)) on parameters such as chemical composition, in situ dry matter digestibility (ISDMD), pH dynamics, volatile fatty acid (VFA) profile, dry matter losses, and organoleptic quality was evaluated. The data was analyzed using a completely randomized design with a factorial arrangement. Results. The use of 70-day regrowth Kikuyu grass reduced (p<0.05) crude protein, digestibility, and energy, while increasing cell wall content and dry matter (DM) of the silage. Additive use reduced (p<0.05) the final pH of mature grass. Small chop size or inclusion of crude glycerin in the whole plant increased (p<0.05) ISDMD. Additive use reduced (p<0.05) the final pH of silage made with the whole plant. Pre-ensiling wilting increased (p<0.05) the DM and final pH, but reduced (p<0.05) crude protein and lactic acid. Conclusion. The use of tender forage, small chop size, and fresh bagging improved the quality of Kikuyu grass silage. The use of mature forage requires the application of additives.

ABSTRACT The objective of this study was to evaluate changes in the biochemical parameters of feedlot lambs fed with high concentrations of crude glycerin (GC). Forty crossbred lambs (Dorper × Santa Inês), non-castrated, weighing 21.7±2.7kg and 90 days old, were randomly assigned to four treatments (0, 10, 20, and 30% GC in the diet). To evaluate the biochemical parameters, blood samples (pre-prandial and 4 h after morning feeding) were collected on the first day and the day before slaughter, in each treatment. The high-density lipoprotein was linearly decreased (P<0.0001) when GC concentrations were increased in the diet. Alkaline phosphatase was quadratically affected by treatments (P=0.05), with greater values observed in blood from animals fed intermediate concentrations of CG, and gamma-glutamyl transferase was linearly increased (P=0.008). The blood urea was quadratically affected by treatments with lower values observed in blood from animals fed intermediate concentrations of CG. In conclusion, the replacement of up to 30% (based on dry matter) of corn grain by crude glycerin, in diets for feedlot finishing lambs, does not compromise the health status of these animals.

RESUMO O objetivo deste estudo foi avaliar as alterações nos parâmetros bioquímicos de cordeiros confinados, alimentados com elevadas concentrações de glicerina bruta (GC). Quarenta cordeiros mestiços (Dorper × Santa Inês), não castrados, com 21,7±2,7kg de peso e 90 dias de idade, foram distribuídos aleatoriamente em quatro tratamentos (0, 10, 20 e 30% de GC na dieta). Para avaliar os parâmetros bioquímicos, amostras de sangue (pré-prandial e 4h após a alimentação matinal) foram coletadas no primeiro dia e no dia anterior ao abate, em cada tratamento. A lipoproteína de alta densidade no sangue diminuiu linearmente (P<0,0001) quando as concentrações de GC foram aumentadas. A fosfatase alcalina foi afetada quadraticamente pelos tratamentos (P=0,05), com valores maiores observados no sangue de animais alimentados com concentrações intermediárias de GC, e a gamaglutamiltransferase aumentou linearmente (P=0,008). A ureia sanguínea foi afetada de forma quadrática pelos tratamentos, com valores menores observados no sangue de animais alimentados com concentrações intermediárias de GC. Em conclusão, a substituição de até 30% (com base na matéria seca) do grão de milho por glicerina bruta, em dietas para cordeiros em terminação em confinamento, não compromete o estado de saúde desses animais.

Abstract The objective of this study was to evaluate the production, fat and fatty acids of milk as well as the diameter, classification and quantity of the milk fat globules (MFG) of goats consuming a diet with 15% of crude glycerin. Twelve multiparous Saanen goats weighing 40 ± 6 kg and 90 ± 5 days of lactation were used. The experimental design was completely randomized with two treatments (0 and 15% inclusion of glycerin). In this way, each milk sample is classified according to the percentage of milk fat globules that were included in these three size categories. For the variables milk production, fat, diameter, medium and large fat globules and amount of globules showed a significant effect of the inclusion of glycerin in the diet (p < 0.05). Fifteen fatty acids were found, mostly saturated. For caprylic, palmitic, and linoleic fatty acids, there was no significant influence of the inclusion of glycerin (p > 0.05). Can recommend the use of 15% double-distilled glycerin in the feeding of lactating goats increased milk production, the amount of fat, increased the size of the milk fat globule. Regarding the saturated and polyunsaturated fatty acids, they kept the level of 15% of glycerin.

Abstract An experiment was conducted to evaluate the effects of increasing concentrations of crude glycerin, with or without ractopamine, in the diet of finishing barrows on carcass characteristics and pork quality. The experimental design was a randomized complete block, in a 4 x 2 factorial scheme, with four concentrations of crude glycerin (0, 100, 150, or 200 g/kg) and two concentrations of ractopamine (0 or 10 mg/kg). There was no interaction between the crude glycerin concentrations and the ractopamine use as well as there was no isolated effect of the dietary crude glycerin concentration for all the evaluated traits. However, the dietary ractopamine increased the hot (p = 0.021) and cold (p=0.020) carcass weight, the hot carcass yield (p = 0.038), the shear force (p = < 0.0001), lightness (L* index) (p = 0.043), hue angle (h*) (p = 0.026), and C16:1 (p = 0.023) concentration in the loin. Moreover, the dietary ractopamine decreased the red content (a* value) (p = 0.043), the activity of C16-C18 elongase (p = 0.037) and the C18:0 (p = 0.021) concentration in the loin. The inclusion of up to 200 g/kg crude glycerin in the diet of finishing pigs may be used as a partial substitute for dietary corn, combined or not with 10 mg/kg ractopamine, without impair the evaluated carcass characteristics and the quality of the loin.

Abstract Crude glycerin is a byproduct of the biodiesel industry and has been widely used in ruminant diets as a source of energy, usually in place of corn, primarily during periods of drought in tropical regions. The objective of this study was to evaluate the effect of including levels of the crude glycerin of low purity (0, 6, 12 and 18%) replacing corn in the diets of goats on the carcass characteristics, tissue composition, meat cuts yield and physicochemical parameters of meat. Forty males castrated without defined racial pattern goats an initial average weight of 19.70 ± 2.30 kg were slaughtered after 86 days. Diets content 0 and 6% crude glycerin promoted similar responses to the analyzed variables, except for pH and breast weight. No differences were observed to total digestible nutrients, slaughter body weight, commercial cut yield leg tissue composition and physicochemical parameters of meat. Crude glycerin can be included up to 12% without losses on carcass weight and meat cuts, leg composition, and meat quality. The inclusion of crude glycerin containing 63.06% glycerol and 45.57% lipids could be effective in partial replacement of corn in diets for confined goats in tropical areas.

ABSTRACT The aim of the present meta-analytical study was to evaluate the effect of glycerol in the diet on the productive performance, nutrient digestibility and the characteristics of the carcass and meat of fattening goats. A systematic review was made using the Google Scholar, ScienceDirect and SciELO databases. Keywords such as crude glycerine, intake, goat, kids, carcass, meat quality were used. As inclusion criteria of the scientific articles, the presence of a control treatment (0% glycerol) and at least a percentage of glycerol in the diet, data regarding the digestibility of nutrients, productive response, characteristics of the carcass and meat and glycerol level in crude glycerin were considered in papers published between 2014 and 2019. In total, 56 articles were selected, of which 11 met the inclusion criteria. Given the heterogeneity or amplitude of the glycerol levels, the levels were grouped: 0, 1.27-4.38 and 6.40-9.60% of glycerol based on the dry matter of the diet. Normality, variance and regression analyses were performed from the data of each variable within each level of glycerol in the diet. The high variation of glycerol levels in crude glycerine was evidenced. Glycerol up to 9.60% in the diet does not compromise digestibility, consumption, main characteristics of the carcass and goat meat.

RESUMEN El objetivo del presente estudio meta-analítico fue evaluar el efecto del glicerol en la dieta sobre el comportamiento productivo, digestibilidad de nutrientes y las características de la canal y carne de cabras en engorde. Se hizo una revisión sistemática utilizando las bases de datos de Google Scholar, ScienceDirect y SciELO. Palabras clave como crude glycerin, intake, goat, kids, carcass, meat quality fueron utilizados. Como criterios de inclusión de los artículos científicos se consideraron la presencia de un tratamiento testigo (0% de glicerol) y por lo menos un porcentaje de glicerol en la dieta, datos referentes a la digestibilidad de los nutrientes, respuesta productiva, características de la canal y carne y nivel de glicerol en la glicerina bruta en trabajos publicados entre 2014 y 2019. Se seleccionaron 56 artículos, de los cuales 11 reunieron los criterios de inclusión. Ante la heterogeneidad o amplitud de los niveles de glicerol, los niveles fueron agrupados: 0, 1.27-4.38 y 6.40-9.60% de glicerol en base a la materia seca de la dieta. Análisis de normalidad, variancia y de regresión fueron realizadas a partir de los datos de cada variable dentro de cada nivel de glicerol en la dieta. Se evidenció la alta variación de los niveles de glicerol en glicerina bruta. Glicerol hasta 9.60% en la dieta no compromete la digestibilidad, consumo, principales características de la canal y carne de cabra.

RESUMO Os valores energéticos da glicerina bruta (GB) foram determinados para frangos de corte em diferentes idades, por meio da utilização do método proposto por Matterson e de regressões polinomiais. Foram realizados dois ensaios: de 11 a 21 dias e de 31 a 41 dias de idade das aves; em ambos, as aves foram distribuídas em um delineamento experimental inteiramente ao acaso, com uma ração referência (RR), sem GB, e três rações testes com substituição de 5%, 10% e 15% da RR por GB. Foram calculados os valores de energia metabolizável pelo método de Matterson, sendo os valores de energia metabolizável aparente (EMA) utilizados na análise de regressão polinomial. Os valores médios da EMA corrigida pelo balanço de nitrogênio (EMAn), o coeficiente de metabolizabilidade da EB (CMAEB) e o corrigido para o balanço de nitrogênio (CMAEBn) da GB, na matéria natural, para a fase de 11 a 21 dias, pelo método de Matterson, foram de 10,08 MJ kg-1, 10,04 MJ kg-1, 67,06% e 66,74%, respectivamente. A inclusão de GB apresentou um efeito linear crescente para os CMAEB e os CMAEBn. Na fase de 31 a 41 dias, foram de 10,38 MJ kg-1, 10,27 MJ kg-1, 69,02% e 62,24%, respectivamente. Por meio das equações de regressões polinomiais, o valor de EMAn estimada foi de 10,49 MJ kg-1 e 10,18 MJ kg-1, respectivamente. Os valores de EMAn da GB para as idades 11 a 21 e 31 a 41 dias foram de 10,04 MJ kg-1 e 10,26 MJ kg-1, respectivamente. De acordo com as equações propostas por Matterson e com o método de Adeola, os valores de EMAn foram 10,49 e 10,20 MJ kg-1 para cada fase.

ABSTRACT The energetic values of crude glycerin (CG) were determined for broilers at different ages using the method proposed by Matterson and by polynomial regressions. Two trials were performed with broilers from 11 to 21 and from 31 to 41 days of age. The birds were distributed in a completely randomized experimental design with a reference ration (RR), without CG, and three ration tests with replacement of 5%, 10%, and 15% of RR by CG. The metabolizable energy values were calculated by the Matterson method, and the apparent metabolizable energy (AME) values were used in polynomial regression analysis. The mean values of AME, apparent corrected for nitrogen balance (AMEn), metabolizable coefficient of gross energy (CAMEB), and corrected for nitrogen balance (CAMEBn) of CG, for the phase from 11 to 21 days by the Matterson method were 10.08 MJ kg-1, 10.04 MJ kg-1, 67.06%, and 66.74%, respectively. The inclusion of CG presented an increasing linear effect for CAMEB and CAMEBn in this period. From 31 to 41 days, these values were 10.38 MJ kg-1, 10.27 MJ kg-1, 69.02%, and 62.24%, respectively. The predicted AMEn value through the polynomial regression equations was 10.49 MJ kg-1 and 10.18 MJ kg-1, respectively. According to the equations proposed by Matterson, the crude glycerin EMAn values for broilers from 11 to 21 and 31 to 41 days of age were 10.04 MJ kg-1 and 10.26 MJ kg-1, respectively. According to Adeola's method the AMEn values were 10.49 and 10.20 MJ kg-1 for each phase.

RESUMO O objetivo deste estudo foi avaliar o perfil de ácidos graxos (AG) do leite de vacas alimentadas com dietas à base de silagem de milho contendo 0% e 8,9% de glicerina bruta (GB) na matéria seca (MS). Foram utilizadas 18 vacas Holandês x Gir com 48±18 dias em lactação, produzindo 19,8±4,9kg/dia de leite. Utilizou-se delineamento de blocos ao acaso, com nove vacas/tratamento e duas medidas repetidas no tempo, com os resultados analisados por modelos mistos. A inclusão de GB na dieta não alterou a ingestão de MS, mas reduziu os consumos dos AG oleico, linoleico e α-linolênico. Os teores dos AG mirístico, palmítico, rumênico, vacênico, esteárico, oleico, linoleico, α-linolênico e CLA trans-10 cis-12 na gordura do leite foram semelhantes entre dietas. A inclusão de GB reduziu os teores dos AG elaídico e C18:1 trans-10 e aumentou os teores dos AG de cadeia ímpar linear e do ácido láurico. Não houve efeito da inclusão da GB sobre os índices de aterogenicidade e trombogenicidade da gordura do leite. Concluiu-se que a inclusão de glicerina bruta em dieta à base de silagem de milho não afetou a qualidade nutricional da gordura do leite de vacas Holandês x Gir.

ABSTRACT The objective of this study was to evaluate the milk fatty acid (FA) composition of cows fed corn silage-based diets containing 0% and 8.9% of crude glycerin (GB) on a dry matter (DM) basis. Eighteen Holstein x Gyr cows with 48±18 days in milk and producing 19.8±4.9kg milk/day were used in the study. The experimental design was a randomized block with nine cows per treatment and two repeated measures. Results were analyzed using mixed models. The milk fat contents of myristic, palmitic, rumenic, vaccenic, estearic, oleic, linoleic, α-linolenic, and trans-10 cis-12 CLA were similar between diets. Dietary inclusion of GB decreased elaidic and trans-10 C18:1, and increased lauric acid and odd linear-chain FA contents in milk fat. Both atherogenicity and trombogenicity indices were unaffected by GB inclusion. It was concluded that GB inclusion in corn silage-based diets had no effect on the nutritional quality of milk fat from Holstein x Gyr dairy cows.

Abstract The aim of this study was to evaluate the effect of different crude glycerin levels in the diet of Nile tilapia fingerlings (mean initial weight 0.32 ± 0.06 g, n = 450) on growth performance parameters, whole-body composition, blood glucose and liver morphology. Crude glycerin was tested at six different levels (0, 4, 8, 12, 16, and 20%) in diets containing 30% digestible protein and 3,000 kcal kg-1 digestible energy. After 37 days of feeding, the inclusion of crude glycerin resulted in positive effects on final weight, visceral fat, weight gain, feed conversion, specific growth rate and feed intake. The different treatments did not influence fillet yield, glycemia, survival and hepatosomatic index, but intermediate levels of inclusion decreased the area of hepatocytes. Regarding fish body composition, significant differences were found in moisture and ash contents, with no changes in crude protein and total lipid. The inclusion of crude glycerin in the Nile tilapia diet improves growth performance without negatively affecting survival rate and glycemia of fingerlings.

ABSTRACT The objective of this study was to evaluate performance, apparent digestibility, blood parameters, and quantitative characteristics of carcass and internal organs of crossbred dairy calves fed different levels of crude glycerin in corn grain-based diets. Twenty-four calves of three months of age and average initial weight of 95.5±11.8 kg were used. The experimental design was completely randomized with four treatments (0, 80, 160, and 240 g kg−1 of crude glycerin of DM of diets). The calves were fed in feedlot until six months of age (195.68±2.38 kg of BW). Dry matter (4.14, 4.11, 3.80, and 3.49 kg day−1) and apparent digestible energy intake (0.43, 0.41, 0.37, and 0.35 MJ kg−1 BW) decreased with increasing levels of glycerin in the diets. There was no effect on the apparent digestibility of nutrients, average daily gain, feed efficiency, carcass characteristics, and blood parameters. The diets did not influence the weights [g kg−1 of empty body weight (EBW)] of lungs, heart, kidneys, liver, omasum, abomasum, and large intestine. The reticulorumen weight (g kg−1 EBW) increased, whereas the small intestine weight decreased with increased levels of glycerin in the diets. The area, height, and width of the rumen papillae were not changed with increasing levels of glycerin. The rumen wall thickness increased with increasing levels of glycerin in the diets. The inclusion up to 240 g kg−1 DM of crude glycerin of in corn grain-based diets for the production of dairy calves does not alter animal performance, carcass characteristics, and weights of internal organs.

Abstract This study aimed to evaluate the productive behavior and metabolic profile of 64 steers (initial weight 364 kg ± 5.9 kg) fed with four experimental diets (16 animals per treatment) with the inclusion of crude glycerin (CG) as a replacement of corn grain. Diets contained 0%, 5%, 15%, and 25% of CG, and steers were fed during 90 days in a completely randomized design. Steers were weighed every 30 days. Blood samples from each steer were taken before the morning feed by puncturing in the coccygeal vein to evaluate serum metabolites. The addition of CG did not affect the variables of productive behavior (p > 0.05). The interaction level of CG per sampling month was significant for glucose (p < 0.05); however, the inclusion of CG did not affect the urea and triglycerides concentrations (p > 0.05). The inclusion of crude glycerin to ruminants’ diets is an energetic alternative when there is low corn grains availability.

Resumen El objetivo de este estudio es evaluar el comportamiento productivo y perfil metabólico de 64 becerros (peso inicial 364 kg ± 5.9 kg) alimentados con cuatro dietas experimentales (16 animales por tratamiento) con la inclusión de glicerina cruda (GC) como reemplazo de grano de maíz. Las dietas contenían 0%, 5%, 15% y 25% de GC y fueron suministradas durante 90 días en un diseño completamente al azar. Los animales se pesaron cada 90 días. Se tomaron muestras de sangre antes del alimento de la mañana para el análisis de metabolitos séricos. La adición de GC no afectó las variables de comportamiento productivo (p > 0.05). La interacción nivel de GC por mes de muestreo fue significativa para la glucosa (p < 0.05). Sin embargo, la inclusión de GC no afectó las concentraciones de urea y triglicéridos (p > 0.05). La inclusión de glicerina en la dieta de rumiantes representa una alternativa energética cuando hay baja disponibilidad de maíz.

ABSTRACT. This study was conducted to evaluate the effects of the inclusion of low-purity crude glycerin (CG, 63.1% of glycerol) in the diets of feedlot-finished goats on the weights and yields of the non-carcass components, with are frequently used in regionals dishes (buchada and panelada). Forty castrated male goats with the initial mean body weight of 19.70 ± 2.30 kg were used. Experimental treatments consisted of inclusion of CG at levels of 0, 6, 12, and 18%, based on dry matter. The weights of the lungs, spleen, total organs (TWO), and TWO yield, as a function of the slaughter body weight, decreased linearly. It was shown that the rumen portion of the weight showed a quadratic effect, at the level of 10.71% of CG, with a minimum point of 0.37 kg. Similar behavior was observed for the reticulum, with a minimum point of 0.08 kg, at the level of 7.5% of CG. The weights and yields of the buchada and panelada were negatively influenced by the experimental diets. Low-purity crude glycerin may partially replace corn and be included in up to 6% of the dry matter of the finished goats' feedlot diet without adversely affecting weights and yields of organs, viscera, and regional dishes, such as buchada and panelada.

ABSTRACT A total of 320 13-weeks-old pullets were weighed and randomly allocated to treatments comprised by four levels of crude glycerin (0, 3, 6 or 9%) and two levels of ME (metabolizable energy, difference of 100 kcal/kg) in the diets growing (14 to 17 weeks of age), pre-lay and pre-peak (low: 2750, 2800 and 2750 kcal/kg and high: 2850, 2900 and 2850 kcal/kg, respectively). During the study, body weight was registered until 30 weeks of age, feed intake, egg weight and egg-production for each repetition and for individual hens were measured every week. The information was analyzed through a completely randomized design with a 4x2 factorial arrangement. During the growing phase, hens that received low energy diets consumed more feed (p<0.05), gained less body weight (p<0.05) and recorded lower feed conversion (p<0.05). Besides, a positive linear effect (p<0.05) was observed when including glycerin on feed conversion and weight gain. During the initial egg-laying phase, hens fed low-energy diets consumed more feed (p<0.05) and laid lighter eggs (p<0.05). Furthermore, a positive linear effect (p<0.05) of including crude glycerin on egg yield and feed intake was observed. After the egg-laying peak, the hens of high energy groups consumed 1.6 g/d less feed (p<0.05) and lay 0.9% less eggs, also, it a quadratic effect of inclusion of glycerin on laying-eggs was observed. In conclusion, the use of high energy diets decrease feed intake, increase egg weight until peak, but decrease the percentage of eggs post-peak; glycerin used in diets increases feed intake and improves egg-laying rate in different ways during the laying phase.

ABSTRACT Fifty-seven primiparous Angus, Hereford, and crossbred cows were used to study the effect of strategic supplementation on metabolic, productive, and reproductive responses. The experiment had two periods including four phases: prepartum supplementation (phase I; 52 days), early postpartum (phase II; 43 days), pre-mating supplementation (phase III; 21 days), and the last phase including mating, gestation, and lactation until weaning (phase IV; 103 days). Phases I and II were considered as period 1, and phases III and IV were considered as period 2. During phase I (−52±2 days before calving to birth), half of the cows received a supplement (S-), and the rest only grazed native swards (C-). For phase III (59±2 days postpartum [DPP] until mating), cows from the previous treatments (C- or S-) were sorted in two levels of pre-mating supplementation, supplemented (-S) or not supplemented (-C), resulting in four treatment combinations (CC, CS, SC, and SS). The supplement was 1 kg dry matter/cow per day of whole rice bran and 550 mL/cow per day of crude glycerin. In period 1, cows receiving prepartum supplementation increased concentration of cholesterol, glucose, and albumin and decreased concentration of non-esterified fatty acids, beta-hydroxybutyrate, and urea. This improvement in energy balance was reflected in a higher body condition score at calving. Alternatively, in period 2, pre-mating supplementation only increased cholesterol concentration. None of the supplementation periods affected the weaning weight of calves. Prepartum, but not pre-mating, supplementation increased total pregnancy rate. A short prepartum supplementation improves pregnancy rate of primiparous cows managed under extensive production systems. However, there is no additional benefit of supplementation during the pre-mating period.

ABSTRACT The morphology of the ruminal and omasal mucosa and hepatic parenchyma of 44 young bulls submitted to four types of concentrates were evaluated by varying the inclusion level of crude Glycerin - CG (0, 6, 12 and 18%). The variables evaluated were number of ruminal papillae per cm² of wall; area of the papillae and total absorption surface per cm² of wall; Mitotic index - MI, height and area of ruminal and omasal papillae; and hepatic morphology. The samples processed for inclusion in paraffin and stained with Hematoxylin-Eosin. The different levels of inclusion of CG in the diet did not interfere either in the number of papillae per cm2 of rumen wall (P= 0,70) or in the ruminal absorptive surface area (P= 0,89). Animals that received diets with levels 12 and 18% had higher MI of the ruminal epithelium (P< 0.01), but higher cell proliferation wasn’t reflected in height gain and papillary area (P= 0,82). The omasal mucosa wasn’t influenced by the inclusion of CG (MI e height gain and papillary area, P= 0,43, P= 0,56 e P= 0,9, respectively). The inclusion of GB in up to 18% of diet dry matter didn’t alter the morphology of the rumen and omaso mucosa; and the integrity hepatic parenchyma.