Effects of maternal dietary nitrate supplementation on farrowing and placental characteristics, level of asphyxiation at birth and piglet vitality.

We investigated whether maternal dietary nitrate supplementation, leading to nitric oxide (NO) formation, would affect duration of farrowing, levels of asphyxiation, vitality of piglets at birth and/or loss of potential viable piglets in the form of stillbirth and pre-weaning mortality. Data were collected from 190 crossbred (Yorkshire x Dutch Landrace) sows, which were allocated, balanced for parity, to six dietary nitrate levels (0, 0.03, 0.06, 0.09, 0.12 or 0.15% of nitrate). Sow received the lactational diet containing nitrate from approximately 7 days before farrowing until 5 days after farrowing. Blood acid-base parameters (pH, pO2, pCO2, BEecf, HCO3, sO2 and lactate) and nitrate concentration were determined in umbilical cord blood. The farrowing process was video recorded and later analysed for total duration of farrowing, piglet birth interval, piglet vitality was scored and piglet latency to stand right after birth. Placentas were collected after expulsion during and after farrowing. Placenta length and width were measured and placental color scores were assessed based on redness of the placenta. The probability of a higher vitality score of piglets (being more vital) linearly increased with increasing levels of maternal dietary nitrate. This higher vitality score however, was not reflected by changes in the blood acid-base parameters in umbilical cord blood, except for a tendency for a higher pO2 with increasing levels of nitrate, which could have been caused by a quicker onset of respiration or an increased blood flow to the piglets during birth. Placenta width increased with increasing levels of maternal dietary nitrate, but no effect on placenta length and redness was found. Neither duration of farrowing nor birth interval were affected by maternal dietary nitrate level. In conclusion, maternal nitrate supplementation may affect piglet vitality via vasodilatation (placental characteristics) rather than an increase in exercise efficiency (duration of farrowing).

Effects of feed access after hatch and inclusion of fish oil and medium chain fatty acids in a pre-starter diet on broiler chicken growth performance and humoral immunity.

Delayed feed and water access is known to impair growth performance of day old broiler chickens. Although effects of feed access on growth performance and immune function of broilers have been examined before, effects of dietary composition and its potential interaction with feed access are hardly investigated. This experiment aimed to determine whether moment of first feed and water access after hatch and pre-starter composition (0 to 7 days) affect growth rate and humoral immune function in broiler chickens. Direct fed chickens received feed and water directly after placement in the grow-out facility, whilst delayed fed chickens only after 48 h. Direct and delayed fed chickens received a control pre-starter diet, or a diet containing medium chain fatty acids (MCFA) or fish oil. At 21 days, chickens were immunized by injection of sheep red blood cells. The mortality rate depended on an interaction between feed access and pre-starter composition (P=0.014). Chickens with direct feed access fed the control pre-starter diet had a higher risk for mortality than chickens with delayed feed access fed the control pre-starter diet (16.4% v. 4.2%) whereas the other treatment groups were in-between. BW gain and feed intake till 25 days in direct fed chickens were higher compared with delayed fed chickens, whilst gain to feed ratio was lower. Within the direct fed chickens, the control pre-starter diet resulted in the highest BW at 28 days and the MCFA pre-starter diet the lowest (Δ=2.4%), whereas this was opposite for delayed fed chickens (Δ=3.0%; P=0.033). Provision of MCFA resulted in a 4.6% higher BW gain and a higher gain to feed ratio compared with other pre-starter diets, but only during the period it was provided (2 to 7 days). Minor treatment effects were found for humoral immune response by measuring immunoglobulins, agglutination titers, interferon gamma (IFN- γ ), and complement activity. Concluding, current inclusion levels of fish oil (5 g/kg) and MCFA (30 g/kg) in the pre-starter diet appear to have limited (carryover) effects on growth and development, as well as on humoral immune function.

Effects of moment of hatch and feed access on chicken development.

The current study evaluated effects of hatch moment and immediate feed and water access within a 24-h hatch window on chicken growth and development. Five hundred four male chickens obtained from a 49-wk-old Ross 308 breeder flock were assigned to 72 cages based on hatching moment (early, midterm, or late; selected during periods of 475 to 481, 483 to 487, and 489 to 493 h after onset of incubation). At the end of each hatching period, chickens were moved to the grow-out facility and one-half of the chickens received feed and water ad libitum immediately. Remaining chickens received feed and water from 504 h after onset of incubation (d 0). Body weight gain and feed intake for each cage were recorded at d 0, 1, 4, 7, 11, and 18. Chickens were sampled at d 4 and 18 for organ and carcass development. Early hatchers had lower BW at placement compared with midterm and late hatchers but compensated for this afterward, resulting in a higher BW at d 4 (112.8, 107.1, and 103.3 g, respectively). From d 0 to 18, early hatchers tended to have higher BW gain than both other groups. Relative breast meat yield at d 18, expressed as percentage of carcass weight, was higher for early (30.4%) than midterm (28.5%) and late hatchers (27.8%). Up to d 7, direct feed access resulted in higher BW gain (6.1%) and feed intake (4.2%) compared with delayed feed access. No effect of moment of feed access on feed efficiency or organ weights was found. Direct feed access resulted in a higher weight:length ratio of the jejunum (12.5%) and ileum (7.5%) at d 4 compared with delayed feed access. These results suggest that early hatchers have a different developmental and growth pattern than midterm or late hatchers within a 24-h hatch window. A mild delay in feed access after hatch affects growth and development during the first week after hatch.

In ovo inoculation of chicken embryos with probiotic bacteria and its effect on posthatch Salmonella susceptibility.

The feasibility of establishing probiotic bacteria in the intestine of broiler chickens by in ovo inoculation was investigated, followed by verifying possible subsequent protection against Salmonella Enteriditis infection. In a first study, 7 commercially available probiotics were screened for compatibility with in ovo inoculation. Two of these probiotics, one being a Enterococcus faecium and the other a Bacillus subtilis, were selected for colonizing the chick gut without compromising hatchability. In a second study, these 2 products were administered in ovo and in the feed to chicks reared until 18 d in comparison with noninoculated chicks and with chicks fed an antibiotic. All chicks were orally challenged with Salmonella Enteritidis at 4 d of age. Results showed reduced performance of Salmonella Enteritidis challenged chicks fed no additives compared with challenged chicks fed antibiotic, but no significant differences in mortality was observed. Probiotics offered in ovo or through the diet could only partially recover performance compared with antibiotic-fed chicks. A significant reduction in the number of Salmonella Enteritidis positive chicks was observed when chicks were in ovo inoculated with E. faecium and continued receiving it in the diet. This work establishes standards for future in ovo colonization research and emphasizes its value as a promising method to deliver individual precise dose of probiotics to poultry in mass scale at the earliest possible age based on the competitive exclusion concept. In ovo colonization with probiotic can therefore become an important ally in combination with other approaches to combat Salmonella and other intestinal bacterial infections in poultry.

Moisture content in broiler excreta is influenced by excreta nutrient contents.

High litter moisture content, often referred to as wet litter, is a major problem in poultry production. Wet litter is often related to poor management, diseases, and digestive problems. In this experiment, the objective was to study the relationship between nutrient content and the moisture content of the excreta of broilers. A dataset containing 351 observations was built and contained the nutrient contents data including moisture content of excreta samples collected in 8 different broiler feeding trials. A biological based model approach was used to create a model with 10 and another one with 14 variables that may explain the excreta moisture level response. Subsequently, these models were compared with a statistical model that was built automatically and adjusted only if this improved the biological model. The R(2) of the 10 variable model was 0.54, in which Zn content and the interaction of NDF × K and Ca × P content were negatively associated with excreta moisture. Sodium, P, and Ca content and the interaction between content of NDF × Na were positively associated with excreta moisture. The R(2) of the 14 variable model was 0.58, in which Zn and K content and the interaction of NDF × protein and Ca × P content were negatively associated with excreta moisture, and Na, protein, P, and Ca content and the interactions in contents of NDF × Na, NDF × Zn, and K × Cu were positively associated with excreta moisture content. In conclusion, the models confirmed the effect of Na, protein, P, and Ca on excreta moisture content. Furthermore, hitherto unknown nutrient interactions that contribute to excreta moisture level were identified. As excreta levels of most nutrients can be manipulated by adjusting dietary nutrient levels, dietary formulation can be adjusted with the findings of this analysis to change levels of excreted nutrients and, consequently, also moisture output.

Effect of different magnesium sources on digesta and excreta moisture content and production performance in broiler chickens.

Reducing litter moisture is an effective measure to reduce the incidence of footpad dermatitis. Dietary mineral levels affect intestinal conditions with regard to osmolarity and water reabsorption. Magnesium is often used as a laxative, preventing reabsorption of water from the digesta, and as a consequence, more moisture in the excreta. The objective of the current experiment was to evaluate Mg in broiler diets as a model for reduced intestinal water reabsorption. Effects of magnesium source (magnesium sulfate, magnesium oxide, and magnesium chloride), each at 3 levels (0.255, 1.02, and 2.04 g·kg(-1) diet), were studied. Measured effects were digesta moisture levels throughout the gastrointestinal tract and the moisture level of the excreta. The 10 treatments were randomly assigned to cages within 6 blocks, resulting in 6 replicates per treatments with 18 birds per replicate. Adding magnesium to the diet of broilers linearly increased the excreta moisture content, following the pattern MgCl > MgSO(4) = MgO. This rejects the hypothesis that MgO and MgCl are less laxative sources compared with MgSO(4). The magnesium sources most likely changed the water reabsorption in the distal gastrointestinal tract, as confirmed by the increased digesta moisture percentage in the ceca and colon. Increasing dietary MgSO(4) linearly reduced BW gain and feed intake, though absolute differences were minor. The results of this experiment show that Mg addition in the diet may be used as a model to study wet litter caused by reduced intestinal water reabsorption.