Biomedical subjects

C Kwakernaak

Publications and source records attributed to C Kwakernaak.

7 recordsLinked to original sources

PubMed2003

Haematological characteristics predicting susceptibility for ascites. 1. High carbon dioxide tensions in juvenile chickens.

1. Male broilers of two different genetic stocks, a pure broiler sire line (A) and commercially available Ross broilers (B), were used to study the effect of haematological characteristics in juvenile chickens on the development of clinical ascitic signs. Production performance (body weight gain (BWG), feed intake (FI), feed conversion ratio (FCR)) from 448 birds per stock was measured from 2 to 5 weeks of age. Mortality was recorded from 2 to 6 weeks of age. The birds were housed at a low ambient temperature to stimulate the incidence of ascites. 2. From each stock, 32 birds with the highest (high risk: HRc) and 32 birds with the lowest (low risk: LRc) carbon dioxide tensions (pCO2) in venous blood were selected at 11 d of age. These birds were marked for future blood sampling to determine changes in pCO2 with age to relate these values to ascites susceptibility. 3. At 2 weeks of age all birds (including HRc and LRc birds) were allotted to 32 floor pens (one HRc and one LRc in each pen) per stock. Venous blood samples were collected weekly from HRc and LRc birds for blood gas analysis and haematocrit, and at week 5 also for thyroid hormone (T3, T4) concentrations in plasma. At 5 weeks of age all HRc and LRc birds were examined post-mortem, relative heart, lung, and liver weights and arterial pressure index (API) values were recorded. 4. Birds from stock A showed a lower BWG and FCR and notably higher ascites mortality compared with stock B. An effect of pCO2 tensions at d 11 was found on the incidence of ascitic signs in selected birds of both stocks up to week 5. From the HRc groups 30% of the birds showed ascitic signs, whereas this was only 8% in the LRc group. LRc birds of stock B in particular showed constant low API values (20 +/- 3%) and none of these birds showed signs of ascites. 5. Our results suggest that the ascites problem in Ross birds can be eliminated by selection for low pCO2 tensions in venous blood. Stock effects on API, liver weight, lung weight, and plasma thyroid hormone independent of pCO2 showed a more complex picture of the ascitic signs in stock A compared with B. 6. We concluded that in this experiment a high pCO2 tension in venous blood measured at d 11 was a reliable predictor for ascites susceptibility observed at 5 weeks of age. A low pCO2 tension provides an appropriate criterion for genetic selection, whereas a high pCO2 tension emphasises the necessity for intensive management in poultry houses.

Animals↗

PubMed2003

Haematological characteristics predicting susceptibility for ascites. 2. High haematocrit values in juvenile chickens.

1. Male broilers of two different genetic stocks, a pure broiler sire line (A) and commercially available Ross broilers (B), were used to study the effect of differences in haematocrit values in 12-d-old chickens on the development of ascitic symptoms. Body weight gain (BWG), feed intake (FI) and feed conversion ratio (FRC) were measured from 2 to 5 weeks of age. Mortality was recorded from 2 to 6 weeks. The birds were kept at a low ambient temperature to stimulate the incidence of ascites. 2. From each stock 32 birds with the highest (High Ht) and 32 birds with the lowest (Low Ht) haematocrit values in venous blood were selected at 12 d of age for an examination on susceptibility for the ascites syndrome at 5 weeks. 3. At 2 weeks 448 birds per stock (including High Ht and Low Ht birds) were allotted to 32 floor pens (1 High Ht and 1 Low Ht in each pen). Venous blood samples were taken weekly in High Ht and Low Ht birds for haematocrit measurements and at week 5 also thyroid hormone (T3, T4) concentrations in plasma were measured. At 5 weeks all High Ht and Low Ht birds were examined post-mortem and arterial pressure index, heart weight, lung weight and liver weight (all relative to body weight) were recorded. High values for arterial pressure index, relative heart and liver weights and low values for relative lung weights and plasma thyroid hormone were considered to be indicators for ascites susceptibility. 4. Stock A, with the highest ascites mortality, had lower values for BWG and FCR than stock B. Throughout, a clear difference in Ht values between High Ht and Low Ht birds was maintained. No significant effects of 12-d haematocrit values were found on the incidence of ascitic symptoms until week 5. High Ht values tended to correlate with low relative lung weights and low plasma T3 concentrations in High Ht birds. 5. Within the groups of selected birds, there was an effect of stock on ascitic symptoms (arterial pressure index, relative heart weight and T3 values) at week 5. This is consistent with a higher ascites mortality in flock A than in flock B, over the whole period up to 6 weeks. Until 4 weeks both A and B were similar with respect to mean Ht values of High Ht and Low Ht groups. After 4 weeks Ht values were very high in the High Ht birds of stock A, possibly as a result of the susceptibility for ascites of stock A. There was a significant interaction between stock and Ht values on the ascites-related variable arterial pressure index. Only in stock A was high arterial pressure at 5 weeks related to high Ht values at d 12. 6. Overall it was concluded that a high Ht in blood of juvenile chickens has limited practical value in predicting incidence of ascites at 5 weeks of age.

Animals↗

PubMed2003

Metabolic rate and its relationship with ascites in chicken genotypes.

1. Male chickens of 7 genetic lines, consisting of two pure sire and two pure dam populations, a commercial broiler cross and two slow-growing chicken lines (Label Rouge, LR and Mechelse Koekoek, MK) were reared from 1 to 37 d of age. The chickens received a two-phase dietary regime and were subjected to low ambient temperature. 2. The experimental aim was to investigate relationships between susceptibility to ascites and heat production. 3. Body weight gain (BWG), food intake and food conversion ratio (FCR) were determined. Ascites mortality, arterial pressure index (API=right ventricular/total ventricular weight ratio), haematocrit values, proportional lung weight (lung weight/body weight x 100), plasma thyroid hormones (thyroxine, T4 and triiodothyronine, T3) and arterial blood gas pressures (pCO2 and pO2) were determined. The heat production per kg metabolic body weight (H/W0.75) and total heat production (H) were calculated for the period 16 to 33 d using an energy balance study according to the comparative slaughter method. 4. The two breeder sire lines had high BWG and low FCR and high but different incidences of ascites compared with the slow-growing ascites resistant LR and MK lines with notable high FCR. The broiler cross and slower-growing breeder dam lines had a similar and relatively lower incidence of ascites mortality. 5. The fast-growing chickens had low H/W0.75 values compared with slow-growing lines. 6. These fast-growing breeder sires had lower plasma thyroid hormone, reduced proportional lung weights, low arterial pO2 and high arterial pCO2 pressures compared with the slower-growing lines. 7. In conclusion, ascites incidence was associated with lower heat production per metabolic body weight and therefore a lower oxygen requirement per metabolic weight.

Animals↗

PubMed2001

Evaluation of between-line variation for within-line selection against ascites in broilers.

Within-line opportunities for selection against ascites were studied in a data set comprising a 10-line comparison. The study attempted to reveal whether contrasts between lines provide reliable candidate traits for within-line selection. Mortality was chosen as the reference trait. As no pedigree information was available, a trait was required that related mortality to the nonmortality data. By principal component analysis, such a trait (ASC_INDIC = ascites indicator) was developed from pathology data. The composite trait ASC_INDIC ranked lines well for their mortality figures (r = 0.96), from which it was concluded that ASC_INDIC represents an underlying continuous ascites trait. Between lines, blood gas traits seemed to be the most promising traits. Within lines, performance traits appeared to be highly correlated to ascites. Comparison of within-line variation to between-line contrasts revealed considerable differences. The high correlation of the blood gas traits with mortality was not present within lines. However, although the magnitude was considerably reduced, the nature of the blood gas traits in their relationship to ascites was similar within and between lines. The study primarily demonstrates that contrasts between lines carry systematic but limited information for within-line coherence. Therefore, line contrasts must be interpreted with care when aiming to study genetic variation and coherence within lines.

Animal Husbandry↗

PubMed1999

High carbon dioxide tension (PCO2) and the incidence of cardiac arrhythmias in rapidly growing broiler chickens.

The purpose of this investigation was to determine whether two-week-old rapidly growing broiler chickens with high metabolic activity have an increased risk of the development of heart failure three to five weeks later. The incidence of cardiac arrhythmias was assessed in broiler chickens with either a relatively high carbon dioxide tension (PCO2) or a low PCO2 in their venous blood. Their electrocardiograms (ECGS) were measured when the birds were between five and seven weeks old by means of a biotransplant which allowed them to move freely. Premature ventricular beats were observed in all the birds, but the largest numbers were observed in birds that had had a high PCO2 when they were two weeks old.

Animals↗

PubMed1999

Performance and physiological variables in broiler chicken lines differing in susceptibility to the ascites syndrome: 1. Changes in blood gases as a function of ambient temperature.

1. Male broilers of 5 genetic stocks (A, B, C, D, E) selected in different ways for fast growth and low food conversion ratio (FCR) and differing in ascites sensitivity were subjected to 2 different ambient temperature step down regimens: high temperature (HT: 33 to 20 degrees C over 33 d) and low temperature (LT: 30 to 15 degrees C over 17 d). 2. Ascites incidence was recorded daily. Food intake and body weight gain were measured weekly and FCR was calculated. Heat production (Hp) was calculated using the comparative slaughter method. At 28 d venous samples were taken for blood gas analysis and haematocrit and relative heart, lung and liver weights were recorded. 3. Populations A and C showed the highest growth rates combined with a low FCR and a higher ascites incidence. A low FCR in these stocks was attributable to low values for Hp. These stocks also had low PO2 and high pCO2 in venous blood at low ambient temperature compared with other stocks. Stock B, which exhibited the slowest growth rate and the highest FCR, was not susceptible to ascites and showed higher Hp and PO2 and pCO2 at low ambient temperature. Populations D and E were intermediate for almost all variables. Heart and lung weights were both increased at LT, while liver weight did not differ between temperature regimes. 4. Our results show that a high haematocrit is not necessarily linked with an increased susceptibility to ascites.

Animals↗

PubMed1999

Performance and physiological variables in broiler chicken lines differing in susceptibility to the ascites syndrome: 2. Effect of ambient temperature on partial efficiencies of protein and fat retention and plasma hormone concentrations.

1. Male broilers of 5 genetic stocks (A, B, C, D and E), selected in different ways for fast growth and low food conversion rate (FCR) and differing in sensitivity to ascites, were subjected to 2 different ambient temperature (Ta) step-down programmes: normal (HT) and low (LT) Ta. 2. Ascites incidence was followed daily. Growth and food intake were measured weekly. Heat production (Hp), oxygen consumption (Oxc) and energy- metabolism parameters were calculated according to the comparative slaughter method. At week 4 blood samples were taken for the analysis of plasma T4, T3, growth hormone (GH) and insulin-like growth factor-I (IGF-1) concentrations. 3. Within-line changes of GH and IGF-1 point to the relative independence of both hormone concentrations. 4. Partial protein efficiency was higher in lines with lower GH, especially at LT. 5. The increase in plasma T3 concentration at LT was accompanied by a decrease in relative fat deposition from the increased energy expenditure. 6. The combination of fast growth and low FCR, linked to a low plasma T4 concentration at LT is indicative of a thyroid insufficiency which is related to an increased occurrence of ascites in these lines.

Adipose Tissue↗