Our objectives were to estimate responses and genetic parameters for ovulation rate, number of fully formed pigs at birth, and other production traits following two-stage selection for increased ovulation rate and number of fully formed pigs. Eight generations of selection were practiced in each of two lines. One selection line was derived from a line that previously selected eight generations for an index to increase ovulation rate and embryonic survival (the IOL pigs). The other selection line was derived from the unselected control line of the index selection experiment (the COL pigs). The control line (C) was continued with random selection. Due to previous selection, Line IOL had greater ovulation rate (4.24 ± 0.38 and 4.14 ± 0.29 ova) and litter size (1.97 ± 0.39 and 1.06 ± 0.38 pigs) at Generation 0 of two-stage selection than did Lines COL and C. In Stage 1, all gilts from 50% of the largest litters were retained. Approximately 50%

There are unknown interactions between supplements of exogenous fibrolytic enzymes (EFE) and the cell walls of feedstuff in ruminal conditions. The quantitative effects of using EFE in ruminant diets were evaluated using meta-analysis. Records (586) were extracted from 74 journal articles from a list of published papers (2000-2012). Statistical analyses were performed considering fixed [type of foragebased diet, forage-to-concentrate ratio (F:C ratio) and primarily enzyme activities in the EFE], and random effects [Experiment(Article)]. In dairy cows fed high-forage (F:C ≥50%), the supplementation of primarily mixtures of cellulases and xylanases (Cel:Xyl: 1:4-1:1) increased milk production and milk composition of legume-based diets, and primarily xylanases (Xyl) EFE improved those variables of grass-based diets. In F: C <50% grass-based diets, Cel:Xyl improved the average daily gain (ADG) and feed conversion [FC:DM intake (DMI)/ADG] of beef cattle. DMI of dairy cows was not affected by EFE supplementation, but EFE improved the DMI of beef cattle. EFE effects were inconsistent in sheep productive performance variables. Cellulases (Cel) and Xyl enhanced in vivo dry matter (DM) digestibility (DMD) in low-forage (F:C <50%) grass-based diets. In F:C ≥50% legume-based diets, EFE enhanced the in situ DM disappearance (ISDMD), and mainly Cel:Xyl improved the in situ neutral detergent fibre (NDF) disappearance (ISNDFD), but there were no effects in those variables in F:C ≥50% grass-based diets. Regardless of the type of ruminal liquid (RL) or forage, in F:C ≥50% diets, in vitro DM degradability (IVDMD) was improved mainly by Cel, but fibre degradability only was improved by Cel:Xyl when sheep RL was used for in vitro evaluations. Overall, EFE could improve the productive performance of dairy cows and beef cattle, but the response depends upon the proper mixture of Cel and Xyl according to the diet composition.

Beef cows were used to determine the influence of calcium soaps of fatty acids (CSFA) incorporated in a range supplement on postpartum reproductive characteristics and growth of calves. Cows were assigned randomly to receive 0 (C, n = 68) or 125 g/d of CSFA (M, n = 66). Diets were isonitrogenous (23%) and were used during 105 d, beginning at 61 +/- 36 d (range) precalving. Two blood samples were collected monthly (7-d intervals). Weights of calves at 35, 50, and 90 d of age and weaning weight adjusted to 200 d of age were greater in M than in C (46.8 vs 43.8 kg, P < .05; 56.0 vs 50.6 kg, P< .01; 98.8 vs 91.8 kg, P < .01; and 186 vs 173 kg, P < .01, respectively). Body weights at 35 and 50 d postcalving were greater in M than in C cows (334 and 310 kg, P < .01; 329 and 300 kg, P < .01, respectively). A similar tendency was observed in body condition scores in the same postpartum periods (4.1 vs 3.4, P < .01 and 3.6 vs 2.5, P < .01 for M and C, respectively). Concentrations of total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, very-low-density lipoprotein cholesterol, and triglycerides were greater (P < .01) in M than in C cows. Percentage of cycling (progesterone > 1 ng/mL) cows at 30 to 90 d postpartum was 38% in M and 22% in C (P < .02). Percentage of pregnant cows during the first half of the breeding season was greater (P < .02) in M (62.5%) than in C cows (35.5%). We concluded that CSFA incorporated in a range supplement during pre- and postpartum periods improved reproductive efficiency and growth of calves.

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Thirty six Landrace × Yorkshire barrows with 18.6 kg of initial body weight were used to evaluate three sources of fatty acids: crude soybean oil, conjugated linoleic acid (CLA), and soybean soapstock in standard crude protein (CP) and low-protein diets for starter (21 d; 205, 160 g kg -1 CP), growing (28 d; 160, 145 g kg -1 CP), and finishing (29 d; 140, 125 g kg -1 CP) phases. Growth performance, carcass characteristics, plasma urea nitrogen concentration and fatty acid profile in meat were evaluated. The reduction of CP diminished average daily gain, feed:gain ratio, longissimus muscle area and plasma urea nitrogen concentration in nursery pigs; reduced longissimus muscle area and plasma urea nitrogen concentration in growing pigs; increased average daily feed intake, and reduced lean meat percentage and plasma urea nitrogen content in finishing pigs. It also increased c9, t11 and c11, t9 CLA isomers and total lipids and lowered eicosapentaenoic and docosahexaenoic acids concentrations in semimembranosus muscle; linolenic acid decreased with low-protein diets in longissimus and semimembranosus muscles; the oil type affected the concentration of c9, t11 and c11, t9 CLA isomers and total saturated fatty acids in semimembranosus muscle; CLA increased individually and total saturated fatty acids, reduced linoleic and docosapentaenoic acids, and increased total lipids in longissimus muscle. These results indicate that decreasing CP changes the profile of fatty acids. The soybean soapstock can replace crude soybean oil in pig diets; while conjugated linoleic acid does not improve response of pigs fed standard-or low-protein diets.Additional key words: feed additives; feeding management; pork meat quality. ResumenEfecto de la fuente de ácidos grasos sobre la respuesta productiva, características de la canal, concentración de urea en plasma y perfil de ácidos grasos en carne de cerdos alimentados con dietas estándar o con baja proteína Se utilizaron 36 cerdos machos castrados (18,6 ± 2,3 kg peso inicial) para evaluar tres fuentes de ácidos grasos: aceite crudo de soya, ácido linoleico conjugado (ALC) y aceite de soya acidulado en dietas estándar en proteína bruta (PB) y con baja proteína para iniciación (21 d; 205, 160 g kg -1 PC), crecimiento (28 d; 160, 145 g kg -1 PC), y finalización (29 d; 140, 125 g kg -1 PC). Se evaluó la respuesta productiva, características de la canal, urea en plasma y perfil de ácidos grasos en carne. La reducción de PB disminuyó la ganancia de peso, conversión alimenticia, área del mús-culo longissimus y urea en plasma en iniciación; redujo el área del músculo longissimus y urea en plasma durante el crecimiento; aumentó el consumo, disminuyó el porcentaje de carne magra y la urea en plasma en finalización. También