Marc-Alexander Lieboldt

Effects of Long-term Graded L-arginine Supply on Growth Development, Egg Laying and Egg Quality in Four Genetically Diverse Purebred Layer Lines

The present study was conducted to examine effects of long-term graded L-arginine supply on growth development, egg laying and egg quality in four genetically diverse purebred layer lines. The study comprised a rearing trial from hatch to week 16 and a following laying performance trial from week 17 to 41. After hatch 150 one-day-old female chicks of each genotype were distributed to three diets. The experimental diets were equivalent to 70, 100 and 200% L-arginine of age-specific recommended level (National Research Council, 1994) and were offered ad libitum to chicks (hatch to week 7), pullets (week 8 to 16) and hens (week 17 to 41). However, hens’ diets were quite low in crude protein. After a pre-laying period from week 17 to 21 thirty-six pullets of each group were used further in the laying performance trial. Independent of chickens genetic background, insufficient L-arginine supply caused lower body weight, daily weight gain and daily feed intake during the rearing (p<0.001) and induced lower laying intensity and daily egg mass production in the laying period (p<0.05). Parameters fitted to Gompertz function suggested higher adult body weight in L-arginine supplemented birds compared to insufficient supplied ones (p<0.01). Groups fed with insufficient L-arginine reached age of maximum daily weight gain later and showed lowest maximum daily weight gain (p<0.001). As a consequence of limitations in dietary L-arginine and crude protein, high performing genotypes decreased strongly in body weight, daily feed intake and performance compared to the low performing genotypes. In conclusion, L-arginine modified the amount of weight gain and feed intake, especially in growing chicks and pullets independent of genetic background. The high performing hens were more nutritionally stressed than the low performing ones, because concentrations of dietary crude protein were relatively low.

Effects of Graded Dietary L-arginine Supply on Organ Growth in Four Genetically Diverse Layer Lines during Rearing Period

Little information has been available about the influence of genetic background and dietary L-arginine (Arg) supply on organ growth of chickens. Therefore, the present study examined the effects of a graded ad libitum Arg supply providing 70, 100 and 200% of recommended Arg concentration on organ growth of female chickens from hatch to 18 weeks of age. The chickens derived from four layer lines of different phylogeny (white vs. brown) and laying performance (high vs. low). Based on residual feed and absolute body and organ weights recorded in six-week-intervals, feed consumption, changes of relative organ weights and allometric organ growth were compared between experimental groups. Surplus Arg caused higher feed intake than insufficient Arg (p<0.01) that induced growth depression in turn (p <0.05). During the entire trial chickens heart, gizzard and liver decreased relatively to their body growth (p<0.001) and showed strong positive correlations among each other. On the contrary, proportions of pancreas and lymphoid organs increased until week 12 (p<0.001) and correlated positively among each other. Due to their opposite growth behaviour (p<0.001), internal organs were assigned to two separate groups. Furthermore, insufficient Arg induced larger proportions of bursa, gizzard and liver compared with a higher Arg supply (p<0.05). In contrast to less Arg containing diets, surplus Arg decreased relative spleen weights (p<0.01). The overall allometric evaluation of data indicated a precocious development of heart, liver, gizzard, pancreas and bursa independent of chickens genetic and nutritional background. However, insufficient Arg retarded the maturation of spleen and thymus compared with an adequate Arg supply. In conclusion, the present results emphasised the essential function of Arg in layer performance, and indicated different sensitivities of internal organs rather to chickens dietary Arg supply than to their genetic background.

Pre-hatching temperature training improves performance in dual- and laying-type cockerels fed with different protein and energy concentrations

The hypothesis of the present study was that pre-hatching temperature training (PTT) with short-term warm stimulation might improve hatching results and have long-lasting effect on growth performance, production efficiency, and robustness in laying-type and dual-purpose cockerels. Further, during the growth period these results may be modified by the protein and energy level of the diet. A total of 2880 eggs (Lohmann Brown-LB/Lohmann Dual-LD) were incubated from day 1 to 17 under normal incubation temperature (37.2–37.4°C) and until hatching in two groups with different temperature programs (control: 37.2–37.4°C or PTT: plus 1°C above standard for 2 h daily). For a subsequent 70 days growing period, 160 LB and 160 LD cockerels from each incubation group were randomly distributed in 8 treatments (8 pens/treatment; 10 birds/pen) resulting from two genotypes of cockerels, two incubation programs, and two dietary protein/energy levels (200 g crude protein/11 MJ AME N/kg – low level, LL; 215 g/12 MJ – high level, HL). PTT had no negative effect on hatching results in LB and LD cockerels. The origin of cockerels had a significant effect on feed intake, growth performance, and feed to gain ratio. The final body weight at day 70 was 85% higher in LD than in LB cockerels (2500 g/1351 g). In LD, but not so pronounced in LB cockerels, performance and production efficiency were significantly improved by PTT. In LD cockerels, the final body weight on day 70 reached in the LL and HL fed groups 2558 and 2528 g, respectively (control: LL 2432 g/HL 2482). Over the total growing period the feed to gain ratio was 10% higher in the LL fed LB/LD groups (2.56/2.29 kg/kg) compared with the HL groups (2.30/2.06 kg/kg). From day 1 until 49, the lowest feed to gain ratio ( P<0.05) of 1.81 kg/kg was calculated for the PTT group of LD cockerels fed with HL feed. Slaughter after 70 days showed significant differences in breast meat and legs, and percentage of abdominal fat between bird genotype and of the different incubated groups. While the thyroid weight was influenced by genotype only, the bursa weight depended also on experienced PTT at the age of 70 days. Possibly, robustness and therefore stress- and immune response might benefit from PTT in both LD and LB cockerels as indicated by increased mean relative bursa weight of 18 and 21%, respectively.