Effect of Sward Surface Height and Level of Herbage Depletion on Bite Features of Cattle Grazing Sorghum Bicolor Swards.

Effect of sward surface height and level of herbage depletion on bite features of cattle grazing Sorghum bicolor swards.

J Anim Sci. 2013 Jul 3;
Fonseca L, Carvalho PC, Mezzalira JC, Bremm C, Galli JR, Gregorini P

To maximize herbage dry matter intake (DMI), pre-grazing sward surface height (SSH) and level of herbage depletion (HD) must be such that variables determining short-term herbage intake such as bite mass (BM) and bite rate (BR) are optimized. The objective of this study was to determine a SSH target and the level of HD as a proportion of the SSH that optimizes BM and BR of beef heifers grazing Sorghum bicolor swards. Two experiments were conducted using two S. bicolor swards and four beef heifers (25 mo old, 322 kg body weight [BW]). Experiment 1 compared the effect of six pre-grazing SSH, 30, 40, 50, 60, 70 and 80 cm on BM, BR and jaw movements. Experiment 2 assessed the effect of HD level as a proportion of SSH (0.17, 0.34, 0.50, 0.67 and 0.84) on BM, BR and jaw movements using the optimal pre-grazing SSH defined in Experiment 1. Short-term herbage DMI was estimated using a double-weighing technique and corrected for insensible weight loss. Herbage DMI was subsequently used to calculate the BM. Net eating time and jaw movements for apprehension and manipulation + mastication while grazing, as well as total jaw movements were determined using the IGER behavior recorders. BR and the number of total jaw movements per g herbage DMI were derived from jaw movement count and measurements of herbage DMI. The results of Experiment 1 showed low and high SSH constraint the ease of herbage harvesting. Greater BM are maintained until a SSH of 50 cm is reached (P < 0.05), then declining at greater SSH due to herbage dispersion. The non-biting jaw movement rate increased at greater SSH, whereas BR decreased (P < 0.05). For both variables, the turning point was close to a SSH of 50 cm. Experiment 2 showed that such an optimization of BM and BR was maintained until an HD level of 0.34 was reached (P < 0.05). There was a linear increase in both the total jaw movements per unit herbage DMI and the non-biting jaw movements rate (manipulation + mastication) subsequent to levels of HD greater than 0.34 (P < 0.05). These studies provide, for the first time, sward feature targets to manage grazing and optimize BM and BR, aiming to maximize the short-term herbage DMI of cattle grazing S. bicolor swards. HubMed – eating


Genetic parameters for different measures of feed efficiency and related traits in boars of three pig breeds.

J Anim Sci. 2013 Jul 3;
Do DN, Strathe AB, Jensen J, Mark T, Kadarmideen HN

Residual feed intake (RFI) is commonly used as a measure of feed efficiency at a given level of production. A total of 16,872 pigs with their pedigree traced back as far as possible was used to estimate genetic parameters for RFI, growth performance, food conversion ratio (FCR), body conformation and feeding behavior traits in three Danish breeds (Duroc (DD), Landrace (LL) and Yorkshire (YY)). Two measures of RFI were considered: Residual feed intake 1 (RFI1) was calculated based on regression of daily feed intake from 30 to 100 kg (DFI) on initial test weight and average daily gain from 30 to 100 kg (ADG2). Residual feed intake 2 (RFI2) was as RFI1, except it was also regressed with respect to backfat (BF). The estimated heritabilities for RFI1 and RFI2 were 0.34 and 0.38 in DD, 0.34 and 0.36 in LL, and 0.39 and 0.40 in YY, respectively. The heritabilities ranged from 0.32 (DD) to 0.54 (LL) for ADG2, from 0.54 (DD) to 0.67 (LL) for BF and from 0.13 (DD) to 0.19 (YY) for body conformation. Feeding behavior traits including daily feed intake (DFI), number of visits to feeder per day (NVD), total time spent eating per day (TPD), feed intake rate (FR), feed intake per visit (FPV) and time spent eating per visit (TPV) were moderately to highly heritable. Residual feed intake 2 was genetically independent of ADG2 and BF in all breeds, except it had low genetic correlation to ADG2 in YY (0.2). Residual feed intake 1 was also genetically independent of ADG2 in DD and LL. Both RFI traits had strong genetic correlations with DFI (0.85 – 0.96) and FCR (0.76 – 0.99). They had low or no genetic correlations with feeding behavior traits. Unfavorable genetic correlations were found between ADG2 and both BF and DFI. Among feeding behavior traits, DFI had low genetic correlations to other traits in all breeds. High and negative genetic correlations were also found between TPD with FR (-0.79 in YY to -0.88 in DD), NVD and TPD (-0.91 in DD to -0.94 in YY) and between NVD and FPV (-0.83 in DD to -0.91 in YY) in all breeds. The genetic trend for feed efficiency was favorable in all breeds regardless of the definition of feed efficiency used. In summary, RFI1 and RFI2 were heritable and selection for reduced RFI2 can be performed without adversely affecting ADG and BF and could replace FCR in the selection index for the Danish pig breeds. Selection could also be based on RFI1 for breeds with fewer concerns about a negative effect of BF or for breeds that do not have BF records. HubMed – eating


Mythbusters: Credibilising strategies in popular nutrition books by academics.

Public Underst Sci. 2013 May 29;
Penders B

Healthy eating is a prominent concern amongst public health and diet professionals. Public understanding of healthy eating presents a topic of interest in understanding scientific credibility in the public domain. Three prominent Dutch nutrition scientists, Kok, Seidell and Katan, have produced popular science books on healthy eating, aiming to remove myths about food and nutrition from the public domain. I describe how they do so, and which strategies they have chosen to achieve this goal. In their books, they move beyond traditional academic strategies to build credibility and devise credibilising strategies resembling those of diet authors. While doing so, they move beyond the deficit model, but end up competing for dietary credibility on the diet authors’ terms. HubMed – eating


Rumination mediates the relationship between peer alienation and eating pathology in young adolescent girls.

Eat Weight Disord. 2013 Jul 4;
Hilt LM, Roberto CA, Nolen-Hoeksema S

This study examined whether rumination, the tendency to passively and repeatedly dwell on negative events, mediated the relationship between peer alienation and eating disorder symptoms among adolescent girls.Participants included 101 girls (ages 10-14; 47 % Hispanic, 24 % African American) who completed questionnaires regarding peer relationships, symptoms of eating pathology, rumination, and depressive symptoms.Girls who reported experiencing more peer alienation reported a higher degree of pathological eating symptoms. The relationship between peer alienation and eating pathology was mediated by rumination, even after controlling for depressive symptoms.This study extends previous work indicating that rumination is a cognitive mechanism that may contribute to the development and/or maintenance of eating pathology. The findings suggest that adolescents who feel alienated by their peers might be particularly susceptible to engaging in ruminative thinking that can lead to or exacerbate eating problems. HubMed – eating



Eating Disorders PSA – A Public Service Announcement concerning Anorexia and Bulimia The Beginning Could Be the End . . . Music: Any Other Name by Michel Simone.