A qualitative and quantitative macroscopic and microscopic study

The transition to using dual-purpose chickens is an alternative to killing male hatchlings of high performance egg-laying chickens. This study aimed to compare the gastrointestinal tract of a recently developed genetic line of dual purpose male chicken, Lohmann Dual (LD), with that of a broiler line, Ross 308. Eighty birds from each line were grown until they reached an average body weight 2000 g (5 weeks for Ross and 9 for LD birds). Six birds of each line were sampled weekly. Body weight (BW), normalized mass of gastrointestinal segments and relative length of intestine were determined. Histologically the villus height, epithelium height, crypt depth, mucosal enlargement factor and the tunica muscularis thickness were measured in jejunum and ileum. Data were regressed against body weight and genetic line. Jejunal enterocyte microvilli and junctional complexes length were measured. Normalized mass and relative length of the gastrointestinal segments were greater in LD birds than in Ross birds at all ages. After day 7 these decreased steadily over the lifetime of the birds in both genetic lines. The growth curves of the gastrointestinal segments of the LD birds were similar to those of the Ross birds. In birds of the same BW, LD birds had a significantly heavier gizzard, shorter intestine, higher jejunal villi, thicker ileal tunica muscularis and smaller ileal mucosal enlargement factor than were found in Ross birds. The large gizzard in LD chickens presumably increases the degree of food processing and enhances availability of nutrients in the orad part of the intestine leading to a lower nutrient concentration and a smaller absorption surface area in the ileum of the LD compared to the Ross chickens. The anatomical differences between the two lines are important criteria for further selection and should be considered in their feeding management

Basic morphometry, microcomputed tomography and mechanical evaluation of the tibiotarsal bone of a dual-purpose and a broiler chicken line

Continuous loading of the skeleton by the body’s weight is an important factor in establishing and maintaining bone morphology, architecture and strength. However, in fast-growing chickens the appendicular skeleton growth is suboptimal making these chickens predisposed to skeletal mineralization disorders and fractures. This study compared the macro- and microstructure as well as the mechanical properties of the tibiotarsus of a novel dual-purpose, Lohmann Dual (LD) and a highly developed broiler, Ross (Ross 308) chicken line. Eighty one-day-old male chicks of each line were grown until their body weight (BW) reached 2000g. Starting at the day of hatching, six birds of each line were sampled weekly. The weight, length and width of the tibiotarsus were measured and its mechanical properties (rigidity, M-Max and the M-fracture) were evaluated using the three-point bending test. Additionally, the mineral density of both, trabecular and cortical bone, the bone volume fraction, the trabecular number, thickness and separation plus cortical thickness of both chicken lines were analyzed using microcomputed tomography. The growth of the tibiotarsus in both chicken lines followed a similar pattern. At the same age, the lighter LD chickens had shorter, thinner and lighter tibiotarsi than those of Ross chickens. However, the LD chickens had a similar cortical thickness, bone volume fraction and similar mineral density of both trabecular and cortical bone to that of Ross chickens. Furthermore, the tibiotarsus of LD chickens was longer, heavier and wider than those of Ross chickens of the same BW. In addition the rigidity of the LD tibiotarsus was greater than that of Ross chickens. This suggests that the tibiotarsus of LD chickens had more bending resistance than those of Ross chickens of the same BW. Consequently, fattening LD chickens to the marketable weight should not affect their leg skeleton stability

Makroskopische, mikroskopische und morphometrische Vergleichsstudie des Magens, des Darmes und der Leber einer Zweinutzungs- und einer Broiler-Hühnerlinie

The poultry industry has specialized in meat and eggs as the two major fields of production. Due to economic reasons, the fattening of male layer breeds is considered to be inefficient in modern chicken industry. Therefore, about 50 million male chicks of laying hens are killed in Germany every year on their first day of life. As an alternative to this, dual-purpose chickens have received much attention in the last years. The new genetic chicken line Lohmann Dual (LD) combines a good laying performance with an acceptable increase of body weight. However, there is still a demand for reliable data on the basic anatomical and physiological responsiveness of the gastrointestinal tract and the liver of LD chickens when fed high-energy diets. The aim of this doctoral thesis was to carry out comparative examinations on the gastrointestinal tracts and the livers of the new LD chicken line and the conventional broiler chicken line Ross 308. The body weight (BW), the weight of the stomach, intestine and liver as well as the intestinal length were measured. Villus and epithelial height, crypts´ depth, the enlargement factor of the intestinal mucosal surface and the thickness of the tunica muscularis were determined. Ultrastructural characteristics of the jejunum were analyzed via transmission electron microscopy. In addition, liver fat content and lymphatic aggregations in the liver were studied histologically; the ultrastructure of the hepatocytes was examined by electron microscopy. Results showed that the weight of the gastrointestinal tract and the liver of LD chickens increased in proportion to the body weight gain, with no abnormalities or deformations observed.. Anatomical differences between the LD chickens and the faster-growing Ross 308 birds were found that may have contributed to a slower growth rate of LD chickens. LD chickens may have lower nutrient absorption capacity due to their shorter intestinal tract and smaller intestinal mucosal surface area, resulting in slower body growth rates than Ross chickens. Liver lipid content of the two chicken lines examined in this study, were within the normal physiological range. Liver lipid content correlated negatively with age and body weight in both lines. In summary this study has not lead to indications that under the described experimental conditions the development of the gastrointestinal tract and the liver of LD chickens are impaired by breeding and selection methods.Die Geflügelindustrie ist auf die zwei Hauptproduktionsbereiche Fleisch und Eier spezialisiert. Da die Mast der männlichen Küken von Legehennen für die Fleischindustrie als ineffizient erachtet wird, werden in Deutschland jedes Jahr am ersten Lebenstag etwa 50 Millionen männliche Legehennenküken getötet. Als Alternative dazu werden Mehrzweckhühner („Dual-purpose“-Hühner) mehr in den letzten Jahren diskutiert. So kombiniert die neue Hühnerlinie Lohmann Dual (LD) eine gute Legeleistung mit einem akzeptablen Mastresultat. Das Ziel der vorliegenden Arbeit waren Untersuchungen am Magen-Darm-Trakt und an der Leber der neuen Hühnerlinie LD im Vergleich mit einer herkömmlichen Broiler-Hühnerlinie (Ross 308), um zuverlässige Daten zur anatomischen Robustheit dieser Organe von LD-Hühnern bei Mast mit energiereicher Nahrung zu erhalten. Das Körpergewicht, das Gewicht des Magen-Darm-Trakts und der Leber sowie die Darmlänge wurden erfasst. Ebenso wurden die Zotten- und Epithelhöhe, die Tiefe der Darmkrypten, der Vergrößerungsfaktor der Darmschleimhautoberfläche sowie die Dicke der intestinalen Tunica muscularis gemessen. Jejunumproben wurden mittels Transmissionselektronenmikroskopie untersucht. Zusätzlich wurden der Leberfettgehalt und Lymphaggregationen in der Leber histologisch und die Ultrastruktur der Hepatozyten transmissionselektronenmikroskopisch analysiert. Die Ergebnisse zeigten, dass sich das Gewicht des Magen-Darm-Trakts und der Leber von LD-Hühnern proportional zur Körpergewichtszunahme entwickelte, ohne dass Anomalien oder Deformationen beobachtet wurden. Einige anatomische Unterschiede zwischen den LD-Hühnern und den schneller wachsenden Ross 308-Vögeln wurden beobachtet, die möglicherweise im Zusammenhang mit der langsameren Wachstumsrate von LD-Hühnern zu sehen sind. Die Ergebnisse geben Hinweise darauf, dass LD-Hühner aufgrund ihrer kürzeren Darmlänge- und kleineren Darmschleimhautoberfläche eine geringere Nährstoffaufnahmefähigkeit haben, was zu langsameren Körperwachstumsraten im Vergleich zu dem der Ross-Hühner führen könnte. Die Veränderungen des Leberlipidgehalts der beiden Hühnerlinien lagen im Untersuchungszeitraum im normalen physiologischen Bereich. Der Leberlipidgehalt korrelierte in beiden Linien negativ mit Alter und Körpergewicht. Insgesamt ergaben diese Untersuchungen keine Hinweise auf Beeinträchtigungen der Entwicklung des Magen-Darm-Trakts und der Leber von LD-Hühnern unter den beschrieben Versuchsbedingungen

Comparison of the gastrointestinal tract of a dual-purpose to a broiler chicken line: A qualitative and quantitative macroscopic and microscopic study.

The transition to using dual-purpose chickens is an alternative to killing male hatchlings of high performance egg-laying chickens. This study aimed to compare the gastrointestinal tract of a recently developed genetic line of dual purpose male chicken, Lohmann Dual (LD), with that of a broiler line, Ross 308. Eighty birds from each line were grown until they reached an average body weight 2000 g (5 weeks for Ross and 9 for LD birds). Six birds of each line were sampled weekly. Body weight (BW), normalized mass of gastrointestinal segments and relative length of intestine were determined. Histologically the villus height, epithelium height, crypt depth, mucosal enlargement factor and the tunica muscularis thickness were measured in jejunum and ileum. Data were regressed against body weight and genetic line. Jejunal enterocyte microvilli and junctional complexes length were measured. Normalized mass and relative length of the gastrointestinal segments were greater in LD birds than in Ross birds at all ages. After day 7 these decreased steadily over the lifetime of the birds in both genetic lines. The growth curves of the gastrointestinal segments of the LD birds were similar to those of the Ross birds. In birds of the same BW, LD birds had a significantly heavier gizzard, shorter intestine, higher jejunal villi, thicker ileal tunica muscularis and smaller ileal mucosal enlargement factor than were found in Ross birds. The large gizzard in LD chickens presumably increases the degree of food processing and enhances availability of nutrients in the orad part of the intestine leading to a lower nutrient concentration and a smaller absorption surface area in the ileum of the LD compared to the Ross chickens. The anatomical differences between the two lines are important criteria for further selection and should be considered in their feeding management