Characteristics of cold-induced dark,firm, dry broiler chicken breast meat

1. A study was designed to characterise dark, firm, dry (DFD) breast meat resulting from cold exposure of broilers and compare its properties with normal breast meat from cold-stressed and control birds.

2. A total of 140 broilers were selected from 5- and 6-week-old birds exposed to cold temperatures ranging from ?18 to ?4°C, or a control temperature of +20°C for 3?h in an environmental chamber. Half of these birds were slaughtered immediately following the cold exposure and the other half were given 2?h of lairage.

3. Breast meat samples were categorised based on ultimate pH (pH_u) and colour L* (lightness) values into normal (5·7?≤?pH_u?≤?6·1; 46?≤?L*?≤?53) breast meat from control (control-normal) or cold-stressed (cold-normal) birds, and DFD (pH_u?>?6·1; L*? 4. Residual glycogen was not different between cold-DFD and control-normal breast meat. Lactate concentration was lower in cold-DFD compared with control-normal breast meat. Lactate concentration almost tripled for all the samples by 30?h post-mortem, which resulted in a drop in pH of normal meat, but did not have any effect on pH of DFD breast meat. Glycolytic potential at both 5?min and 30?h post-mortem was lower in DFD breast meat compared with the normal breast meat from both cold-stressed and control birds.

5. Cold-DFD breast meat was significantly darker, with higher pH_u, lower cook loss, higher water-binding capacity and processing cook yield than cold-normal and control-normal breast meat, which were not different from each other.     

Improvement of the nutritive value of rye for broiler chickens by gamma irradiation‐induced viscosity reduction

1. A study was undertaken with chickens to determine the effect of irradiation treatment on the viscosity‐inducing properties of polysaccharide components of rye.

2. Three‐week body weight, food utilisation, fat retention, and bone ash of chicks were substantially improved by irradiating rye (0 to 10 Mrad) and were maximal at 6 Mrad. Irradiation of the entire diet resulted in no further improvement over irradiating the rye fraction alone.

3. The improved performance coincided with radiation‐induced damage to rye polysaccharides, as indicated by reduced viscosity and increased concentrations of reducing sugars.     

Endogenous Progesterone Concentrations Affect Progesterone Release from Intravaginal Devices Used for Oestrous Synchronization in Cattle

Intravaginal progesterone‐releasing devices are largely used both as contraceptives in humans and as a component of oestrous synchronization protocols in cattle. To reduce costs in large‐scale timed artificial insemination, the reuse of these releasing devices is common. Passive hormone diffusion, however, depends on the concentration gradient, which could affect the amount of residual progesterone present in these devices after a first use. To evaluate the effect of the presence of a corpus luteum in the release of progesterone from intravaginal devices, three synchronization protocols were designed to simulate the effects of inserting the device in the early dioestrus, late dioestrus or anoestrus. Holstein‐Zebu cross‐bred heifers were randomly allocated into one of these three treatments, and a series of blood samples was taken to evaluate the plasma progesterone concentrations. After 8 days, the intravaginal devices were removed and underwent a previously validated alcoholic extraction technique to measure the residual progesterone. Non‐used devices were used as controls. As expected, the simultaneous presence of the intravaginal device and a corpus luteum resulted in increased plasma progesterone concentrations. Conversely, the amount of residual progesterone in the devices after use was inversely proportional to the plasma progesterone concentration. These results demonstrate that the release rate of progesterone from intravaginal devices is affected by the endogenous concentration of this hormone; consequently, the strategy for reuse should account for the category and expected luteal cyclic activity of the animals undergoing synchronization protocols.