Se evaluó la ganancia diaria de peso (GDP) de ovinos de pelo tipo Sudán en crecimiento utilizando 1,090 registros tomados durante dos años en tres granjas localizadas en el trópico seco en la región del Caribe de Colombia. En cada una de las granjas se registró el tipo de parto de la oveja y el sexo de los corderos. Para determinar la GDP, los corderos se pesaron semanalmente desde el nacimiento hasta los 240 días de edad. Los datos se analizaron según un diseño estadístico completamente aleatorizado con arreglo factorial 3 (granjas) x 2 (sexo del cordero) x 3 (tipo de parto, sencillo, doble o triple). Se utilizó la prueba de Tukey para la separación de medias. La GDP fue similar entre las tres granjas evaluadas con un promedio general de 112 g. Se observó en promedio una mayor (P<0.05) GDP en hembras que en machos (115 versus 103 g) y tal como esperado, la GDP individual de corderos producto de partos sencillos (117 g) fue mayor (P<0.05) que la de corderos nacidos de partos dobles (106 g) o triples (23 g). La mayor GDP de corderas se observó en dos de las tres granjas. La GDP fue similar en machos o hembras nacidos de partos sencillos, sin embargo, en corderas nacidas de partos dobles la GDP fue mayor (P<0.05) que en corderos, y lo contrario se observó en partos triples donde la GDP fue 32 g mayor (P<0.05) en machos que en hembras. En resumen, la GDP de ovinos de pelo tipo Sudán en la región del Caribe de Colombia es buena dado su sistema de crianza extensivo. La GDP fue similar entre fincas pero difirió entre el sexo de la cría y el tipo de parto.

In two experiments, we studied the characteristics of ensiling and aerobic stability of triticale (x Triticosecale spp.) ensiled with or without a homolactic bacterial inoculant (HBI). The first experiment used 60 vacuum-sealed 0.946 L glass jar mini-silos (GJ) to determine the effect of ensiling on pH, dry matter recovery (DMR) and temperature. Three GJ per treatment were opened on d 0, 1, 2, 3, 5, 7, 14, 30, 105 and 123 of fermentation. Across all lengths of fermentation, inoculation decreased (P<0.05) average silage pH and temperature upon opening the mini-silos but did not influence (P>0.05) DMR versus the Non-HBI silage. Both silages had a similar (P>0.05) pH at the end of 123 d of fermentation. The second experiment compared the nutritional and fermentation characteristics and aerobic stability of triticale ensiled with or without HBI for 123 d in either 3L PVC mini-silos packed manually (PVC) or vacuum-sealed GJ. There was little difference (P>0.05) in silage nutrient content using PVC or GJ mini-silos, nor did inoculation affect these variables. Ensiling triticale decreased (P<0.05) its 30 h neutral detergent fiber (NDF) digestibility, the lowest value being that of Non-HBI/ PVC silage, which differed (P<0.05) from the HBI/PVC silage, but these did not differ (P>0.05) from the GJ silages. Differences among silages were not found (P>0.05) in NDF at 240 h (uNDF240), total tract NDF digestion (TTNDFD) and rate of NDF digestion (NDFkd). Triticale ensiled well in GJ, however the amount of material ensiled may have been too small to detect differences due to inoculation.

CONSUMO Y DIGESTIBILIDAD DE NUTRIENTES DE HENO DE MANÍ RIZOMA PERENNE Y ALFALFA COMERCIAL

Fresh whole plant spring triticale (x Triticosecale spp.) was field wilted and chopped prior to either being sprayed or not with a homolactic bacterial inoculant (HBI). Wilted triticale was ensiled for 120 d at 20 to 23 °C using 16 PVC mini-silos of 3 L capacity fitted with two-way mechanics to vent gas (which imposed aerobic stress (ASTS) when it remained open), and filled with about 2 kg of the crop containing 35% dry matter (DM) and 5.2% water soluble carbohydrates (WSC) in the DM. Four treatments of a 2x2 factorial were: 1) No HBI/vent closed; 2) HBI/ vent closed; 3) No HBI/vent open; 4) HBI/vent open. Upon opening the mini-silos, chemical composition, fermentation characteristics and in vitro 30 h neutral detergent fiber (NDF) digestibility of the silages were determined. Relative to pre-ensiled forage, either sprayed or not with HBI, ensiling increased (P<0.05) contents of moisture, inorganic matter, fibrous fractions (acid detergent fiber (ADF) and lignin), and ether extract (EE), while decreasing contents of WSC and non-fibrous carbohydrates (NFC). However, treatment had no consistent effect on content of silage nutrients. Of the two non-inoculated silages, the one subjected to ASTS was more than 20 percentage points lower (66 vs. 88 %) in DM recovery (DMR), whereas the HBI silage subjected to ASTS was protected from DM losses. Ensiling and ASTS during the 120 d fermentation decreased NDF digestibility, whereas inoculated non-ASTS silage was nearly as digestible (57.5) as the pre-ensiled forages (58.2 and 60.7%, without and with HBI). Inoculation tended to steer fermentation in a homolactic direction. On balance, HBI is recommended because of the benefits in the fermentation pattern, fiber digestibility and DMR, especially in the presence of ASTS.

The objective of this study was to determine physiological parameters (rectal temperature = RT, respiratory rate = RR, heart rate = HR) and production parameters (dry matter intake = DMI, water intake = WI, average daily weight gain = ADG, and feed conversion = FC) of crossbred and Katahdin lambs raised in rotational grazing of native pastures (NP) and in confinement under heat stress conditions. Nine crossbred lambs (average initial weight = 19.4 kg) were used and fed in a rotational grazing system for 70 days with occupation and rest periods of seven and 21 days, respectively. The lambs had daily access to the grazing area for four to six hours, grass hay and water ad libitum, a daily supplement of 100 g of commercial concentrate and a nutritional block. In the confined system, six lambs of the Katahdin breed (average initial weight = 27.3 kg) were used, and for 28 days these were fed total mixed rations (TMR) containing 30% grass hay, 15.4% soybean meal, 54.6% corn grain and a mineral block. The diet contained 14% Crude Protein (CP) and 66% Total Digestible Nutrients (TDN) and was formulated for an ADG of 200 g. The offered and rejected feed was quantified every day [4% body weight (BW)/dry matter basis (DMB)] to determine the DMI, and the volume of water offered and rejected to determine WI. To validate the stress conditions, the maximum environmental temperature and relative humidity were monitored to calculate the temperature and humidity index (THI), and the RT, HR and RR of the 15 lambs were determined. The lambs were weighed every seven days. In both experiments, the THI oscillated between 78 and 80. The lambs were under environmental heat stress conditions (THI x̅ = 79) during both studies. The averages of HR and RT in the grazing system were 118.0 beats per minute and 38.6° C, while the averages under the confinement system were 108.6 beats per minute and 39.4° C, respectively. The average RR (53.6 and 62.6 breaths per minute, in grazing and in confinement, respectively) was greater than the normal value considered for thermal comfort. Respiratory rate is the main mechanism used by lambs to dissipate heat. The heart rate also showed slightly higher values than those reported for animals in their comfort zone. However, the rectal temperature values were constant. As expected, crossbred lambs fed under grazing conditions with naturalized pastures (NP) had a low ADG (55.6 g). Nevertheless, Katahdin lambs fed in confinement with TMR had a DMI of 935.4 g/day (3.14% BW/DMB), a WI of 3.5 L/day, a FC of 4.74 and an ADG of 226.2 g. In conclusion, raising crossbred sheep in rotational grazing of NP without any type of agronomic management results in ADG that could not be considered viable in traditional production systems. The introduction of pure breeds and feeding them in confined systems with a TMR results in a pre-determined ADG (>200 g/day) and is an alternative that can be evaluated economically for its practical implementation.