A dietary deficiency of Arg may suppress chick immune system functions; however, research evaluating immune function responsiveness of commercial broilers fed dietary Arg levels near NRC (1994) recommendations is sparse. Therefore, three experiments were conducted to evaluate growth and immunity of broilers fed varying Arg levels near NRC (1994) specifications. Because Arg and Lys are similar in structure and are known to compete in intestinal absorption, dietary Lys treatments [near NRC (1994) recommendations] were evaluated to determine if Arg and Lys interact to affect broiler immunity. There were four dietary treatments in Experiment 1 representing a 2 x 2 factorial design of additional Arg (120% of NRC) or additional Lys (120% of NRC) added to a control diet containing 100% of NRC Arg and Lys (six replications per treatment). Experiment 2 contained the following four treatments: the control diet; the control diet plus L-Arg (0.20% Arg of diet); the control diet plus L-Lys HCl (0.20% Lys of diet); and the control diet plus L-Arg-L-Glu (0.10% Arg of diet). Graduations of Arg were fed from 90 to 120% of NRC in 10% increments in Experiment 3. Also, half of the birds were exposed to vaccinations of Newcastle disease virus and infectious bronchitis virus in Experiment 3 to derive a 2 x 4 factorial design. Experiments 1 and 2 were conducted from Days 1 to 18 and Experiment 3 was conducted from Days 1 to 15 in Petersime battery brooders. No interactions occurred between dietary Lys and Arg in Experiment 1. Increasing dietary Arg, but not Lys, from 100 to 120% of the NRC recommendation increased (P < or = 0.05) Day 18 BW gain. Treatment differences in the cutaneous basophil hypersensitivity assay in Experiment 1 did not occur. In Experiment 2, treatment differences in growth responses, lymphoid organ development, and primary antibody titers to SRBC did not occur. Unvaccinated birds in Experiment 3 fed an Arg-deficient diet had lower (P < or = 0.05) feed conversion in comparison with vaccinated birds fed an Arg-deficient diet. Vaccinated birds had lower (P < or = 0.05) Day 15 BW than unvaccinated birds, but higher (P < or = 0.05) titers to Newcastle disease virus. Increasing dietary Arg in Experiment 3 increased plasma Arg (P < or = 0.05), but did not affect plasma Lys. Although increased dietary Arg improved BW gain in Experiment 1, minimal effects were noted in growth and immune system parameters throughtout this study. A dietary Arg level near the NRC (1994) recommendation should support proper immune system functions in healthy chicks.

1. The present study was undertaken to determine the effects of heat exposure on fertility, semen quality, and semen ion concentrations of broiler breeders classified on sperm quality index (SQI) before heat stress. 2. Cobb males (108) were individually caged in 6 temperature-controlled rooms. Each room contained an equal number of males from each of the 4 SQI population quartiles as follows: best (B), good (G), fair (F), and poor (P). Three rooms were heated to 35 degrees C, and the other three rooms were maintained at a constant 23 degrees C as controls. For each SQI group in each room, 15 Leghorn hens were artificially inseminated (5 x 10(7) sperm/hen) once a week for 8 weeks for fertility observations. 3. Body weight, sperm concentration, SQI, and fertility of P males were lower than in the other three SQI groups. Body temperature of the top three SQI groups was increased by heat exposure, but body temperature was not altered by heat stress in the P group. Fertility, sperm viability, and SQI of the top three SQI groups, but not the P group, was decreased by heat stress. Seminal plasma K+ of P males was lower than that of B males. However, seminal plasma Ca2+ concentration of P males was higher than that of B males. 4. In conclusion, high ambient temperatures had more impact on semen quality and fertility of males in the top 75% of the SQI population than in males in the bottom 25% of the population. In addition, calcium ions (Ca2+) appear to play a major role in heat stress infertility.

Previous research has shown that the sperm quality index (SQI) of rooster semen is indicative of overall semen quality. The objectives of the present experiments were to determine the correlation of the SQI with semen characteristics and fertility and to determine if selection of young males for the SQI would improve fertility. In Experiment 1 semen was collected from 35 Peterson males and was analyzed individually for sperm concentration and viability. To determine fertility, 100 microL of diluted semen was inseminated into 10 hens for each rooster. Positive correlations of the SQI with total and live sperm concentrations as well as fertility were found. A negative correlation of the SQI with the percentage of dead sperm was observed. In Experiment 2, four semen samples were collected at 2- to 3-d intervals from each of 142, 27-wk-old Peterson roosters to determine their SQI. Males were then allocated to six treatment groups based on their average SQI readings as follows: 0 to 150, 151 to 200, 201 to 250, 251 to 300, 301 to 350, and >350. For each SQI group, semen was collected weekly for 8 wk, pooled, and used at a rate of 50 microL/hen to inseminate 40 hens. The percentage of fertilized eggs increased linearly across the SQI groups, from a minimum of 65% for the 0 to 150 SQI group to a maximum of 98% for the >350 SQI group. The SQI groups of 301 to 350 and >350 produced the slowest decline in fertility over days postinsemination. Therefore, selection of males for the SQI at an early age appears to improve flock fertility.

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