Differences In Performance Traits Research Articles

PSX-A-1 Impacts of Undigestible NDF and Grain Source in Feedlot Steers on Performance, Feeding Behavior, and Ruminal pH

Abstract Little is known about how fiber quality impacts rumen health in feedlot diets with minimal forage inclusion. The objective of the study is to investigate the interaction between undigestible NDF (uNDF) levels and grain fermentability (GF) on animal performance, feeding behavior, and ruminal pH in feedlot steers. Using a 2x2 factorial design, Angus crossbred steers (n=96, 505±54 kg) were fed an isonitrogenous and isocaloric diet containing: high uNDF (haylage; 12% uNDF) or lower uNDF (corn silage, 6% uNDF) and high (high moisture corn) or lower ruminally fermentable grain (rolled corn) yielding 4 different treatments. Following adaption, steers were fed their treatment ration for 102±14d before slaughter. Feed intake (DMI) and feeding behavior data were collected using Insentec feeders and continuous ruminal pH was measured during the last 4 weeks before slaughter using indwelling pH probes (12 steers/treatment). Liver abscesses and gut health scores were assessed at slaughter. Steers on the low uNDF diet had greater ADG (P≥0.005) and improved F:G (P≥0.005) for the first half of the finisher period. No other differences in performance traits were found for the second half or overall finisher period between uNDF and GF, or their interaction. DMI (P≥0.64) did not differ, but time spent at the feeder (min/day) was greater (P≥0.02) for low GF steers. Steers fed low uNDF had greater (P≥0.04) time per day spent with ruminal pH below pH 5.8. At slaughter, steers fed high GF treatments had greater hot carcass weights (P≥0.03). This data suggests that low uNDF can improve early gain but may result in increased SARA risk compared to high uNDF at the same forage inclusion level. However, there was limited interaction with grain processing. Further research should continue to investigate relationships between uNDF and ruminal pH, and dietary uNDF concentrations that optimize performance without compromising gut health.

Climate‐related geographical variation in performance traits across the invasion front of a widespread non‐native insect

AbstractAimInvasive species are ideal systems for testing geographical differences in performance traits and measuring evolutionary responses as a species spreads across divergent climates and habitats. The European gypsy moth, Lymantria dispar dispar L. (Lepidoptera: Erebidae), is a generalist forest defoliator introduced to Medford, Massachusetts, USA in 1869. The invasion front extends from Minnesota to North Carolina and the ability of this species to adapt to local climate may contribute to its continuing spread. We evaluated the performance of populations along the climatic gradient of the invasion front to test for a relationship between climate and ecologically important performance traits.LocationEastern United States of AmericaTaxonLymantria dispar dispar L. (Lepidoptera: Erebidae)MethodsInsects from 14 populations across the US invasion front and interior of the invasive range were reared from hatch to adult emergence in six constant temperature treatments. The responses of survival, pupal mass and larval development time were analysed as a function of source climate (annual mean normal temperature), rearing temperature and their interaction using multiple polynomial regression.ResultsWith the exception of female development time, there were no significant interactions between source climate and rearing temperature, indicating little divergence in the shape of thermal reaction norms among populations. Source population and rearing temperature were significant predictors of survival and pupal mass. Independent of rearing temperature, populations from warmer climates had lower survival than those from colder climates, but attained larger body size despite similar development times. Larval development time was dependent on rearing temperature, but there were not consistent relationships with source climate.Main ConclusionsThermal adaptation can be an important factor shaping the spread of invasive species, particularly in the context of climate change. Our results suggest that L. d. dispar is highly plastic, but has undergone climate‐related adaptation in thermal performance and life‐history traits as it spread across North America.

Differences In Performance Traits In Intermittent Versus Continuous Exercise Testing Of Handball Players and Triathletes

Differences In Performance Traits In Intermittent Versus Continuous Exercise Testing Of Handball Players and Triathletes

Studies on quantitative trait loci related to superoxide dismutase in mirror carp (Cyprinus carpioL.)

The F1 progeny from parents selected randomly for differences in performance traits from different families of mirror carp were used as a mapping panel. Linkage maps constructed using Join Map 4.0 software with 992 microsatellite polymorphic markers ultimately yielded 51 groups. Composite interval mapping (CIM) of superoxide dismutase (SOD) trait of three tissues (liver, anterior and posterior intestine) was conducted for quantitative trait loci (QTL) location using Map QTL 6.0 software. Results shows that seven QTLs significantly (P 85%). These results showed that it is highly probable that these QTLs are the main regions of SOD expression. The data also support the value of forward genetic studies on organism development and serve as a basis for selection.

Consistency of individual variation in feeding behaviour and its relationship with performance traits in Nile tilapia Oreochromis niloticus

Feed intake is commonly used as one of the most important performance indicators in fish. However, very little is known about the behavioural processes involved in ingesting food such as meal duration, feeding frequency and latency to start eating. This study aims at the characterization of feeding behaviour in Nile tilapia Oreochromis niloticus in terms of consistency of individual differences over time and correlation with performance traits. Seventy-two individuals were individually housed for 27 days. These fish had three different weight (age) categories: low (initial body weight: 61.32 ± 5.97 g), middle (151.19 ± 4.26 g) and high (265.90 ± 19.13 g), each containing 24 fish. Daily feed intake was recorded per fish. On days 8, 15 and 21 feeding behaviour was assessed by measuring the latency to start feeding (LAT, min), the total feeding time (TFT, min) and the number of feeding acts (NFA). In the end of the experimental period, fish were weighed and individual growth rate and feed efficiency (measured as residual feed intake) determined. Results show that feeding latency and the number of feeding acts have significant repeatability estimates for all weight classes. These estimates were, however, low in magnitude and decreased as the weight class increased. The correlation between the different feeding behaviours showed that individuals that are more active during feeding (higher NFA) on average, start to consume their feed earlier (lower LAT) and for longer periods (higher TFT). The number of feeding acts was significantly correlated with both feed intake and growth in all size classes. The residual feed intake was correlated with feeding latency only in the small weight class. These results showed that individual differences in feeding behaviour have low repeatability estimates and can partly explain differences in performance traits in juveniles of Nile tilapia.