SELENIUM AND VITAMIN E SUPPLEMENTATION OF HIGH N-ALKANE GROWN YEAST IN CHICK DIETS

A total of four experiments have been conducted to evaluate performance of chicks given high (300/kg diet) n-alkane grown yeast diet supplemented with vitamin E and selenium. Four levels (0,10,20,30 mg) of vitamin E were examined in experiment 1 while five levels (0,12.5,15.0,17.5,20mg) were examined in experiment 2. Performance was also measured at four selenium supplementation levels (0, 50,100, 150 µg Se/kg diet) initially and finally at five other (0,100, 125, 150, 175 µg/kg diet) more detailed levels. Supplementation of a 300g/kg yeast diet with 15mg Vitamin E produced significantly (P < 0.05) higher body weight than unsupplemented high yeast diet. Higher levels produced no further growth response. At this level of vitamin E supplementation every level of selenium examined gave significant (P < 0.05) increase in weight but optimum growth response was obtained at 100µg Se/kg yeast diet. There were no significant treatment effects on feed intake at all levels of vitamin E and selenium examined. Nitrogen retention also showed no response at the highest levels (100 - 157µg) of selenium supplementation. The results show that supplementation with appropriate levels of vitamin E and selenium significantly reduced the depression in growth rate caused by high levels of inclusion of n-alkane grown yeast in chick diet.

Reconstructing Greater Sage-Grouse chick diets: Diet selection, body condition, and food availability at brood-rearing sites

ABSTRACT Growth and survival of juvenile birds is nutritionally demanding, making the availability of major foods critical to population productivity. Access to nutritious foods for juveniles has important implications because poor foraging conditions during development could result in mortality, or reduced fitness in adulthood. Selection of brood-rearing habitats by female Greater Sage-Grouse (Centrocercus urophasianus) thus has broad implications to survival of juveniles and persistence of populations. Previous research using crop contents demonstrated that invertebrates and forbs comprise the major portion of sage-grouse chick diets for the first few months post-hatch. We coupled stable isotope analysis of feathers and field measurements to quantify chick diet and then correlated that with measures of chick body condition. We sought to reconstruct sage-grouse chick dietary history (2013–2015) using nitrogen stable isotopes to (1) evaluate whether selection of brood-rearing habitats by female sage-grouse was related to chick diet, and (2) assess the relationship between dietary consumption and body condition. Brood-rearing females selected habitats in areas where diet resources occurred in proportion to their availability, with the exception that females selected areas with greater forb abundance 4 weeks after hatch. Diet assimilation by chicks at brood-rearing locations was unrelated to the availability of forbs and invertebrates, but consumption of forbs increased with chick age. Chicks that assimilated proportionally greater amounts of plant-derived nitrogen in their feathers during their first week of life tended to weigh more and have longer wing chords. This relationship was similar between male and female chicks. The importance of quality foods for sage-grouse is well recognized and conservation efforts should aim to maintain functioning sagebrush ecosystems containing adequate brood-rearing habitats for juvenile sage-grouse; there remains a need to identify whether desirable effects are achievable when attempting to improve big sagebrush (Artemisia tridentata) habitats to benefit sage-grouse populations.