RESUMEN
The reproductive impact following controlled introduction of animals persistently infected (PI) with bovine viral diarrhea virus (BVDV) was evaluated in BVDV-naive heifers. Heifers were randomly allocated into two groups: an unexposed control herd (n = 34) and a herd exposed to five persistently infected (PI) animals for 7 mo, beginning 50 days before the breeding season (n = 34). Initiation of the BVDV-challenge was timed to mimic either direct contact with PI calves born in the previous calving season or accidental introduction of PI herd additions prior to the breeding season. The PI animals represented BVDV Types 1a (n = 3), 1b (n = 1) and 2 (n = 1). Two BVDV-free, seropositive bulls were used in each group for 78 days breeding seasons. In both groups, 33 of 34 heifers became pregnant, with similar distribution of fetal ages. Two heifers in each group aborted (etiology undetermined). In addition, one calf was born dead and one calf died 3 days post-partum in the BVDV-exposed group. One calf in the unexposed group died 4 mo post-partum. No calves, including the stillborn calf and the two calves that died prior to weaning, were persistently infected with BVDV. In summary, introduction of PI cattle to a group of BVDV-naive heifers 50 days prior to the breeding season did not negatively impact reproductive performance. To the contrary, the active immunity that developed following field exposure to BVDV provided effective reproductive and fetal protection during the breeding season and subsequent gestations, despite continuous exposure to PI animals until approximately midgestation. Although BVDV can have potentially devastating reproductive effects, timing of infection is a critical determinant in the outcome of a BVDV infection. A controlled breeding season with introduction of herd additions at less critical reproductive time points can mitigate the negative reproductive health consequences of BVDV.
Asunto(s)
Diarrea Mucosa Bovina Viral/inmunología , Diarrea Mucosa Bovina Viral/prevención & control , Reproducción , Animales , Anticuerpos Antivirales/sangre , Diarrea Mucosa Bovina Viral/economía , Cruzamiento/economía , Bovinos , Análisis Costo-Beneficio , Virus de la Diarrea Viral Bovina/inmunología , Femenino , Masculino , Embarazo , Complicaciones Infecciosas del Embarazo/veterinaria , Complicaciones Infecciosas del Embarazo/virología , Estaciones del AñoRESUMEN
Duroc-cross pigs (n = 25) were assigned to one of three experimental finishing diets containing 0 (control), 40,000 (40), or 80,000 (80) IU of supplemental vitamin D3/kg of feed (as-fed basis)to test the effects of vitamin D3 on pork quality traits. Experimental diets were fed for 44 or 51 d before slaughter, and days on feed were blocked in the experimental design. A trend existed for pigs receiving the highest concentration of vitamin D3 supplementation to have a lower (P = 0.08) ADG (0.77 kg/d) compared with pigs fed either the 40-diet (0.88 kg/d) or control (0.92 kg/d). Diet did not (P > 0.10) affect backfat thickness measured along the midline, 10th-rib fat depth, longissimus muscle area, muscle score, or hot carcass weights. Longissimus pH, measured at 0.5, 1, 2, 3, 4, and 24 h postmortem, was higher (P < 0.05) for pigs on the 80-diet than those fed the control diet. Longissimus muscle color, measured at 24 h postmortem, from pigs fed either the 40- or 80-diet were darker (lower L* values; P < 0.05) than those fed the control diet. Objective longissimus color scores were higher (P < 0.01), and firmness/wetness scores lower (P < 0.05), for pigs on the 80-diet as compared to those on the 40-diet or control diet. The diet had no (P > 0.10) effect on Warner-Bratzler shear force values; percentage of cook loss; or trained sensory panel evaluations for tenderness, juiciness, and flavor. Feeding the 80-diet increased (P < 0.05) plasma vitamin D3 and calcium after 2, 4, and 6 wk on feed compared with the control diet. Vitamin D3 and 25-hydroxy vitamin D3 concentrations in the longissimus muscle increased (P = 0.001) with increasing vitamin D3 levels in the diet; however, muscle calcium concentrations and fiber type were not (P > 0.30) affected by diet. These results indicate that feeding supranutritional levels of vitamin D3 for at least 44 d improves pork color and increases pH, but may retard growth if fed at 80,000 IU/kg of feed.
Asunto(s)
Alimentación Animal , Colecalciferol/administración & dosificación , Carne/normas , Músculo Esquelético/metabolismo , Porcinos/metabolismo , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Calcio/análisis , Colecalciferol/análisis , Colecalciferol/metabolismo , Suplementos Dietéticos , Relación Dosis-Respuesta a Droga , Femenino , Concentración de Iones de Hidrógeno , Masculino , Músculo Esquelético/química , Pigmentación , Cambios Post Mortem , Distribución Aleatoria , Porcinos/crecimiento & desarrollo , Gusto , Factores de TiempoRESUMEN
A possible management strategy to alter fetal development and enhance sow productivity and progeny performance was examined by maternal administration of porcine somatotropin during early gestation. Eighteen crossbred gilts were bred naturally to boars of similar genetics, and pregnancy was confirmed between Days 21 and 24 of gestation by ultrasound. All animals were allowed ad libitum consumption of a 16% CP gestation diet through Day 21 of gestation and 3.0 kg/d for the remainder of gestation. Gilts were injected twice daily with 0 (n = 10) or 15 micrograms/kg body weight (BW) (n = 10; total, 30 micrograms/kg BW per d) pituitary-derived porcine somatotropin (pST) during Days 28 to 40 of gestation. Data were collected postmortem during embryonic, neonatal, and market-weight phases. At 41 d of gestation, pST treatment increased embryonic survival (87.9 versus 77.0%; P < 0.05) and embryo crown rump lengths (77.96 versus 65.14 mm; P < 0.01), but embryo weight was not altered (10.15 and 9.03 g; P > 0.10). Pigs from pST-treated gilts had increased (P < 0.01) crown rump lengths at birth (31.5 versus 30.4 cm) and 21 d (50.9 versus 48.4 cm). However, no differences were observed in birth or 21-d weights as a result of pST treatment (P > 0.10). Neonatal carcasses of progeny (20 kg BW) from the pST-treated gilts had heavier semitendinosus muscles (76.1 versus 66.0 g; P < 0.10), larger longissimus muscle cross-sectional area (10.1 versus 8.2 cm2; P < 0.05), longer sides (51.2 versus 47.9 cm; P < 0.001), and decreased 10th rib backfat (6.67 versus 8.64 mm; P < 0.001) compared with those of controls. Carcasses of market-weight progeny (100 kg BW) from pST-treated gilts had larger longissimus muscle cross-sectional area (P < 0.10), heavier trimmed loins (P < 0.10), and longer carcass sides (P < 0.05). Data are supportive of a hypothesis that mechanisms during early embryonic development are sensitive to manipulation through selected management strategies of the sow and that modifications of this strategy may serve as a model for the examination of molecular and cellular events controlling early embryonic growth.
Asunto(s)
Animales Recién Nacidos/crecimiento & desarrollo , Desarrollo Embrionario y Fetal/efectos de los fármacos , Hormona del Crecimiento/farmacología , Porcinos/crecimiento & desarrollo , Animales , Peso Corporal/efectos de los fármacos , Peso Corporal/fisiología , Desarrollo Embrionario y Fetal/genética , Desarrollo Embrionario y Fetal/fisiología , Femenino , Expresión Génica , Factor I del Crecimiento Similar a la Insulina/análisis , Intercambio Materno-Fetal/fisiología , Músculo Esquelético/anatomía & histología , Músculo Esquelético/fisiología , Miogenina/genética , Embarazo , Radioinmunoensayo , Porcinos/genética , Porcinos/fisiologíaRESUMEN
Effects of age and diet composition on amylase, trypsin and chymotrypsin activities in the pancreas and intestinal contents, pancreas weights and body weights were determined from birth to 56 d. A total of 120 pigs, five to seven pigs/litter from 18 litters, were slaughtered at birth, 14, 27, 29, 31, 42 and 56 d. Litters were allotted to dietary treatments (corn-soy, A; corn-soy + 20% dried whey, B; corn-soy + 5% lard, C) and offered these diets as creep feed at 14 d. All pigs were weaned at 28 d, placed in elevated nursery pens and fed their respective diets. Total activities of amylase, trypsin and chymotrypsin in the pancreas and small intestine increased (P less than .05) with age. Both trypsin and amylase activities, measured per kilogram body weight or gram pancreas weight, were low at 29 d in the intestine and increased to 56 d. Pigs on diet B had the highest level of trypsin and chymotrypsin in the intestinal contents (P less than .05). Trypsin activity in the pancreas (units/kg body weight) was lowest (P less than .05) for pigs on diet B and highest (P less than .05) for those on diet C (units/g pancreas and units/kg body weight). Amylase activity (units/kg body weight) was lower (P less than .05) in the pancreas for pigs on diet B than for those on diets A and C. Pigs on diet A had lower (P less than .01) intestinal amylase activities than those on diets B and C. Enzyme activities in the intestinal contents and pancreas were low following weaning. In the pancreas, activities decreased at 31 d.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Envejecimiento , Amilasas/biosíntesis , Quimotripsina/biosíntesis , Dieta , Páncreas/crecimiento & desarrollo , Porcinos/metabolismo , Tripsina/biosíntesis , Amilasas/metabolismo , Animales , Peso Corporal , Quimotripsina/metabolismo , Femenino , Masculino , Tamaño de los Órganos , Páncreas/enzimología , Tripsina/metabolismoRESUMEN
Dried whole whey, lard or dried skim milk was added to a corn-soybean meal basal diet to determine the effect on apparent nitrogen (ND), energy (ED) and dry matter digestibility (DMD) in pigs weaned at 28 d. Four groups of four littermate barrows were allotted to the experimental diets and placed in individual metabolism pens for 12 d (3 d adjustment and three collection periods of 3 d each) after weaning. The study was a 4 X 3 factorial with diet and period as main effects. Addition of dried skim milk or dried whey to the diet resulted in higher values (P less than .05) for DMD and ED as compared with the basal or corn-soy and lard diet. Pigs fed added dried skim milk had improved (P less than .05) ND over pigs on other dietary treatments. All nutrient digestibility coefficients increased (P less than .05) from period 1 to period 2, and ND increased (P less than .05) from period 2 to 3. It was concluded that the young pig requires at least 6 to 9 d after weaning at 28 d to adjust to typical corn-soybean meal starter diets.
Asunto(s)
Dieta , Metabolismo Energético , Nitrógeno/metabolismo , Porcinos/metabolismo , Animales , Digestión , Masculino , DesteteRESUMEN
The effect of sorghum particle size on nutrient digestibilities at the terminal ileum and over the total digestive tract of growing-finishing pigs were investigated in a replicated 3 X 3 Latin square trial. Sorghum-casein diets were used. Sorghum was dry rolled (C) or ground in a hammer mill through 6.4 mm (M) or 3.2 mm (F) screens, producing particles with a modulus of fineness of 3.57, 2.85 or 2.36, respectively. Each successive reduction in particle size improved (P less than .05) the apparent ileal digestibility of dry matter, starch, gross energy and N. Measured over the total digestive tract, digestibilities of these components were highest (P less than .05) for the F diet but they did not differ (P greater than .10) between diets M and C because of increased (P less than .05) disappearance in the large intestine of dry matter, starch and gross energy from the C diet. N loss in the large intestine was also higher for pigs fed diet C than for those fed diet M, but the difference was not significant. The digestibilities of most amino acids at the terminal ileum were improved (P less than .05) as particle size decreased. Lysine digestibilities were not affected (P greater tha .10). Amino acid digestibilities measured over the total digestive tract were consistently higher (P less than .05) for diet F than diets M and C, which did not differ (P greater than .10) from one another. A comparison of ileal and total tract digestibilities indicated a net disappearance of all measured amino acids except lysine during large intestine transit. These data indicate that increasing fineness of grind will improve digestibility of nutrients in sorghum by growing-finishing pigs.