Short-term fasts increase levels of halogenated flame retardants in tissues of a wild incubating bird

Many species are adapted for fasting during parts of their life cycle. For species undergoing extreme fasts, lipid stores are mobilized and accumulated contaminants can be released to exert toxicological effects. However, it is unknown if short-term fasting events may have a similar effect. The objective of this study was to determine if short successive fasts are related to contaminant levels in liver and plasma of birds. In ring-billed gulls (Larus delawarensis), both members of the pair alternate between incubating the nest for several hours (during which they fast) and foraging, making them a useful model for examining this question. Birds were equipped with miniature data loggers recording time and GPS position for two days to determine the proportion and duration of time birds spent in these two activities. Liver and plasma samples were collected, and halogenated flame retardants (HFRs) (PBDEs and dechlorane plus) and organochlorines (OCs) (PCBs, DDTs, and chlordane-related compounds) were determined. Most birds (79%) exhibited plasma lipid content below 1%, indicating a likely fasted state, and plasma lipid percent declined with the number of hours spent at the nest site. The more time birds spent at their nest site, the higher were their plasma and liver concentrations of HFRs. However, body condition indices were unrelated to either the amount of time birds fasted at the nest site or contaminant levels, suggesting that lipid mobilization might not have been severe enough to affect overall body condition of birds and to explain the relationship between fasting and HFR concentrations. A similar relationship between fasting and OC levels was not observed, suggesting that different factors are affecting short-term temporal variations in concentrations of these two classes of contaminants. This study demonstrates that short fasts can be related to increased internal contaminant exposure in birds and that this may be a confounding factor in research and monitoring involving tissue concentrations of HFRs in wild birds. © 2015 Elsevier Inc

Initial heifer body composition has little impact on response to Zilmax

Using a growth promotant at the correct time of finishing is critical for maximizing profit potential. Previous studies have shown that zilpaterol-HCl (Zilmax; Intervet/ Schering-Plough Animal Health, Millsboro, DE) improves carcass characteristics. The objective of this study was to determine effects of prior body composition on subsequent changes in carcass weight, fatness, and muscle in heifers fed Zilmax so producers can introduce Zilmax at the level of finish that will result in the most desirable response. We hypothesized that fatter heifers use fat as the fuel for muscle growth

Effect of extended postmortem aging and steak location on myofibrillar protein degradation and Warner-Bratzler shear force of beef M. semitendinosus steaks

Citation: Phelps, K. J., Drouillard, J. S., Silva, M. B., Miranda, L. D. F., Ebarb, S. M., Van Bibber-Krueger, C. L., . . . Gonzalez, J. M. (2016). Effect of extended postmortem aging and steak location on myofibrillar protein degradation and Warner-Bratzler shear force of beef M. semitendinosus steaks. Journal of Animal Science, 94(1), 412-423. doi:10.2527/jas2015-9862The objective of this study was to evaluate the effect of steak location and postmortem aging on cooked meat tenderness and myofibrillar protein degradation of steaks from M. semitendinosus (ST). Following harvest and a 6 d chill period, the left ST was removed from carcasses of crossbred feedlot steers (n = 60, average hot carcass weight 427 +/- 24 kg). Each ST was fabricated into ten 2.54-cm thick steaks originating from the proximal to distal end of the muscle. Steaks cut adjacent to each other were paired, vacuum packaged, and randomly assigned to 7, 14, 21, 42, or 70 d of aging at 2 +/- 1 degrees C. After aging, within each steak pair, steaks were randomly assigned to Warner-Bratzler shear force or myofibrillar proteolysis analysis (calpain activity and desmin and troponin-T degradation). Muscle fiber type and size were also determined at the 2 ends of the muscle. There was no location x d of aging interaction (P = 0.25) for ST steak WBSF. Steak location affected (quadratic, P 0.13). Type I, IIA, and IIX muscle fibers were larger at the proximal end of the muscle than the distal end (P < 0.01). Increasing d of aging improved WBSF (quadratic, P < 0.01) for the duration of the 70 d postmortem period. As d of aging increased, intact calpain-1 activity decreased (quadratic, P < 0.01) with activity detected through 42 d. Day of aging affected autolyzed calpain-1 (linear, P < 0.01) and calpain-2 activity (quadratic, P < 0.01). Through d 70 of aging, the intensity of intact 55 kDa desmin band decreased (linear, P < 0.01), while there was an increase (linear, P < 0.01) in the degraded 38 kDa band. Similarly, d of aging increased troponin-T proteolysis, indicated by a decrease (quadratic, P < 0.01) in intensity of the intact 40 kDa band and an increase (linear, P < 0.01) in the 30 kDa degraded band. Intramuscular WBSF differences are not due to proteolytic activity or myofibrillar degradation and seem related to muscle fiber size. The improvement of ST steak WBSF through 70 d of aging is partly due to continued degradation of desmin and troponin-T. Calpain proteolytic analysis indicates that autolyzed calpain-1 and calpain-2 may be involved in extended postmortem myofibrillar protein proteolysis

Effects of Postmortem Aging Time and Muscle Location on Objective Measures of Semitendinosus Steak Tenderness

Beef tenderness is the most important trait affecting consumer beef eating satisfaction. Cuts from muscles with superior tenderness (tenderloin, ribeye, striploin) are consequently most highly valued, but because of recent record-high beef prices, the need to identify more economical cuts that will meet consumer expectations for tenderness is greater than ever. The eye of round (Semitendinosus) has traditionally been marketed as a lower-value cut, primarily owing to its inherent toughness. Tenderness improves throughout postmortem aging and continues to improve in muscles aged for greater than 35 days. Retail steaks from the Semitendinosus receive, on average, 17 days of aging, with almost half (48.5%) receiving less than 14 days. This indicates a significant opportunity for tenderness improvement of Semitendinosus steaks through extended aging times. In many muscles, including the Longissimus, tenderness depends on anatomical location. Tenderness is often reduced in regions of the muscle closest to the ends or in close proximity to heavy connective tissue seams. Very little is known about the effects of aging and anatomical location on the tenderness of the Semitendinosus. Warner-Bratzler shear force testing is commonly used to measure beef tenderness objectively. Consumers rate beef with shear values of 9.5 lb as “tender,” so if tenderness of Semitendinosus steaks can be improved to meet this threshold, then the eye of round may offer a suitable alternative to higher-valued cuts for consumers and an opportunity for increased value for processors. Thus, the objectives of this study were to evaluate the effects of aging and anatomical location on the tenderness of Semitendinosus steaks

Effect of the Programmed Nutrition Beef Program on moisture retention of cooked ground beef patties and enhanced strip loins

This study evaluated the influence of the Programmed Nutrition Beef Program and exogenous growth promotants (ExGP) on water holding capacity characteristics of enhanced beef strip loins. Sixty, frozen strip loins, arranged in a 2 × 2 factorial treatment arrangement with dietary program serving as the first factor and use of ExGP as the second factor, were thawed, injected with an enhancement solution, and stored for 7 days. Loins from ExGP cattle possessed the ability to bind more (P 0.10) before injection, but increased post-injection and after storage (P 0.10). The Programmed Nutrition Beef Program and use of ExGPs minimally impacted water holding capacity of enhanced frozen/thawed beef strip loins

The influence of diet properties and feeding rates on PCB toxicokinetics in the ring dove

The influence of diet properties and feeding rate on the uptake and elimination of polychlorinated biphenyls (PCBs) was investigated in ring doves (Streptopelia rissoria). Elimination rates of PCBs were determined in birds dosed with an Aroclor mixture (1242:1248:1260, 1:1:1) and allowed to depurate on uncontaminated high-lipid or low-lipid/high-fiber diets for 105 days. Uptake rates for seven additional PCBs not found within the above Aroclor mixtures were studied in the same birds by feeding high- or low-lipid PCB-spiked diets for 15 days. The two diet treatments contributed to differences in feeding rates, fecal egestion rates, and total fat volume of the birds. Uptake rate constants of PCBs were higher for the low-lipid diet group, whereas PCB assimilation efficiencies were similar between the two groups. Whole-body elimination rates of Aroclor PCBs were most strongly influenced by the chlorine substitution pattern of the congeners, such that PCBs containing an open meta-para site on one of the phenyl rings were rapidly cleared from the animal. Whole-body elimination rates for persistent PCBs could only be determined for PCB 28; other congeners exhibited negligible elimination over the depuration period. For the latter compounds, fecal elimination rates were estimated using the excreta/carcass distribution coefficient and excreta production rates. For PCB 28, the fecal elimination rate was similar to the whole-body elimination rate, suggesting that fecal elimination of persistent PCBs dominates whole body elimination of these compounds. Diet treatment effects were less evident for PCB elimination rates compared to uptake rates. Steady-state biomagnification factors were estimated to range from 1.0 to 5.1 for rapidly cleared PCBs and from 27 to 97 for persistent congeners