Estimation of the carcass composition from a cross-section of the rib-loin from crossbred Japanese Black × Limousin F2 cattle by computer image analysis

The carcass composition of crossbred Japanese Black × Limousin F2 cattle was examined in order to find an accurate carcass composition equation. The test animals included 17 steers and 17 heifers. The 28 image measurements from the area encircling the vertical line to the thoracic vertebra and the line from the thoracic vertebra between the sixth and seventh rib‐bones were measured by computer image analysis. The relationships between the 29 parameters that added the carcass left side weight of the animal and the carcass composition were suggested. The carcass composition included muscle weight, muscle ratio, fat weight and fat ratio. The carcass composition from steers was estimated by an equation composed of these three or four parameters (R² = 90.80%, 79.30%, 90.75% and 73.70%, respectively). The selected parameters were measured without cutting the thoracic vertebra. The carcass composition from heifers was estimated by an equation composed of two to four parameters (R² = 96.15%, 90.98%, 93.60% and 88.22%, respectively). The parameters for the estimation of the muscle and fat weight, and muscle and fat ratio are very similar. Furthermore, the equations using the parameters could estimate the carcass composition from the Japanese Black × Limousin cattle resource population.     

Effects of feeding different levels of concentrate on growth and carcass characteristics in younger Japanese Black cattle

The effects of a higher concentrate feed during the raising period on the growth and carcass of Japanese Black cattle being fattened at a younger age were investigated using three pairs of artificially bred identical twins and three pairs of full‐sibs. The animals were fed the concentrate at 2.4%/day (2.4% group) and 1.2%/day (1.2% group) comparative bodyweight (BW) during the raising period. The BW and subcutaneous fat thickness were measured every month using ultrasonic equipment. The animals were slaughtered at the age of 24 months. The BW of the 2.4% group from the age of 6–10 months appeared to be higher than that of the 1.2% group (P < 0.1). The subcutaneous fat of the 2.4% group from the age of 7–11 months was thicker than that of the 1.2% group (P < 0.1). After those ages, the BW and subcutaneous fat of the two groups did not differ and there was no difference in the carcass characteristics between the two groups. Using a higher concentrate feed during the raising period for younger fattening of Japanese Black cattle influenced growth from the late half of the raising period to the early part of the fattening period.     

Development of X-ray computed tomography for live standing cattle

An X‐ray computed tomography (CT) system for live standing cattle was developed for studying the meat yield, carcass composition and so on. The gantry contained three X‐ray tubes and detectors that corresponded to each X‐ray tube. The system was able to operate while the animal remained standing. The scan area had a diameter of 900 mm. The Musculus longissimus and Musculus trapezius areas, and the back fat thickness in the CT image were evaluated and compared to the actual cross‐section of the carcass using eight cattle. The differences among the muscles, and the subcutaneous and intermuscular fat were easily recognized. The correlation coefficient between the CT image and the actual carcass photograph of the M. longissimus area and the back fat thickness was high (r = 0.84, r = 0.93, P < 0.01). The present study demonstrated that muscle, fat and bone can be clearly imaged from a live standing animal using X‐ray equipment.     

Production of Middle White Piglets after Transfer of Embryos Produced In Vitro

The present study was conducted to examine the feasibility of in vitro embryo production and transfer technologies for producing Middle White piglets. After collection from three retired Middle White sows, a total of 222 oocytes were matured, fertilized and cultured in vitro, and a total of 50 embryos from the 4-cell to blastocyst stage were produced by the 4th or 5th day. These embryos were transferred individually into three recipients along with 5 in vivo-derived Duroc blastocysts. All of the recipients became pregnant, and they farrowed a total of 9 Middle White and 9 Duroc piglets. These results suggest that in vitro embryo production using ovaries from retired sows is useful for reproduction of pigs of pure breeds including the Middle White for breeding activities and conservation/utilization of genetic resources.     

Successful Production of Piglets Derived from Expanded Blastocysts Vitrified Using a Micro Volume Air Cooling Method without Direct Exposure to Liquid Nitrogen

This study was conducted to clarify the feasibility of newly developed vitrification techniques for porcine embryos using the micro volume air cooling (MVAC) method without direct contact with liquid nitrogen (LN₂). Expanded blastocysts were vitrified in a solution containing 6 M ethylene glycol, 0.6 M trehalose and 2% (wt/vol) polyethylene glycol in 10% HEPES-buffered PZM-5. The blastocysts were collected from gilts and vitrified using the new device (MVAC) or a Cryotop (CT). Blastocysts were stored in LN₂ for at least 1 month. After warming, cryoprotective agents were removed using a single step. Survival of the embryos was assessed by in vitro culture (Experiment 1) and by embryo transfer to recipients (Experiment 2). In Experiment 1, the embryos vitrified by the MVAC or CT and fresh embryos without vitrification (Control) were used. The survival rates of embryos in the MVAC, CT and Control groups were 88.9% (32/36), 91.7% (33/36) and 100% (34/34), respectively, after 48 h culture, and the hatching rates of embryos after 48 h incubation were 69.4% (25/36), 63.9% (23/36) and 94.1% (32/34), respectively. In Experiment 2, 64 vitrified embryos were transferred to 5 recipient gilts, and 8 healthy piglets were produced from 3 recipients in the MVAC group. Similarly, 66 vitrified embryos were transferred to 5 recipient gilts, and 9 healthy piglets were produced from 2 recipients in the CT group. These results indicated that porcine expanded blastocysts can be cryopreserved using the MVAC method without potential pathogen contamination from LN₂.     

Effects of high protein levels in concentrate feed during the early fattening stage on physico-chemical composition and sensory characteristics of M. longissimus in Japanese Black heifers

The effects that high levels of protein in concentrate feed has during the early fattening stage on physico-chemical composition and sensory characteristics of M. longissimus in Japanese Black heifers were investigated. Four sets (8 head) of identical twins of Japanese Black heifers were divided into two groups: a group fed high levels of protein in concentrate feed in the early fattening stage (HCP); and a control group. Moisture, fat, protein, cooking loss, Warner-Bratzler shear force and fatty acid composition of M. longissimus were similar in both groups. Levels of free amino acid (FAA), aspartic acid, glutamine, taurine and histidine were lower in the HCP group than in the control group ( P  < 0.05). Levels of glutamic acid, serine, asparagine, threonine and total FAA in the HCP group tended to be lower than in the control group ( P  < 0.1). There were no significant differences between the sensory characteristics (juiciness, tenderness, fattiness, flavor and overall acceptability) of the two groups. These results suggest that the use of high levels of protein in concentrate feed during the early fattening stage does not affect the sensory characteristics of Japanese Black beef, but does alter the FAA content.