Abattoir Practices and Animal Products Technology

SLAUGHTER AND DRESSING OF PIGS

         Hog slaughter is carried out in a separate hall from that used for sheep or cattle as the moist atmosphere due to the scalding of hog is not conducive to the setting and drying of beef or mutton carcasses.

Equipment

• Shackles, Gambrel, Sticking knife, Scalding tank or vat, Bell scraper, Stunning instrument, Hoist, Dressing knife, Splitting saw.

Procedure

• Hold hogs are off feed for 24 hours prior to slaughter, but ample water is available. Some evidence indicates that hams will cure better and livers will weigh more if some feed is available. Hogs should always be well rested before slaughter. Dirt and manure are washed from hogs.
• After stunning the hog is hooked and shackled around one pastern and the hog hoisted to a convenient height for sticking (hogs may be conveniently stuck by holding the hog on its back on the floor).
• Using a sticking knife or skinning knife, small incision is made on the skin just anterior to the point of the breastbone. Knife inserted above the breastbone at a distance of 2 -1/4 inches, pointing the knife towards the rectum, then completed a quarter circle with a downward motion. The motion will sever the carotid artery and jugular vein providing a thorough bleeding. The knife should be kept on the centre line otherwise a shoulder stick will result, and this will require unnecessary waste when trimming the shoulder.
• Bleeding is allowed thoroughly (4-10 minutes). All blood is washed off and dropped into the scalding vat.
• The scalding water should register (60–64⁰C). This should be checked with the thermometer and the finger test. Hog is kept moving in the scalding water until hair gets pulled out easily, usually for 4-5 minutes, then removed and scraped with bell scraper, or mechanical scraper. All dewclaws and toenails should be removed.
• Carcass is washed down with hot water and shaved off all remaining hair while on cambering table.
• The tendons attached to the gambrel are loosened and hung on hog trolley.
• Singeing: This is done with blowtorch, blowgun or blowlamp but if neither is available, any remaining hair around the eyes, ears, etc., should be shaven off with the knife.
• Washed thoroughly with hot water, then with cold water, and scraped up - the hog is now ready for dressing.

Dressing of hogs

The following outline includes all the steps that must be taken in a manner

• The pig should be thoroughly scraped and cleaned. The mid-line of the ventral side form the rectum to the point of the jaw is opened down.
• The breastbone is split.
• The bung loosened and pulled out several inches to be sure that it is free. Then tied with string.
• Body cavity is opened (be careful to avoid cutting entrails). If a barrow or boar, the penis must be loosened.
• The intestines are loosened. The kidney and Kidney fat are left intact.
• Intestines, liver and stomach are lifted out.
  • Hands are slipped down the inside of the body cavity, then forward along the diaphragm, lifting out all abdominal entrails with an upward motion.
  • Oesophagus is cut.
  • Liver is removed - gal bladder stripped off - liver washed and weighed.
  • All abdominal entrails are weighed.
• Diaphragm removed. Membrane only has to be cut out, leaving muscle intact.
• With a downward motion, lungs and heart are pulled out, including the aorta. These are known as the thoracic entrails, sometimes called the pluck.
• Inside of each jawbone is cut down, then along the dorsal side of the tongue to loosen, and then the pluck is to be pulled out.
  • Heart and tongue are removed - washed, weighed and plattered.
• Head at the atlas joint is removed, leaving the jowls on the carcass. The head is weighed.
  • Cheek meat and other head trimmings including brain are removed.
• The inside of the carcass is washed.
• An incision is made down the median line of the back, all the way from the tail to the anterior end. (The fat layer should not be cut cleared through)
• The carcass is split down the middle of the backbone using splitting saw.
• Endeavoured to split each vertebral process evenly.
• Flesh or back fat are left attached near the anterior end. (This will prevent carcass from slipping off the gambrel)
• Carcass is washed again with cold water, both outside and inside.
• The carcass is weighed and tagged. Tag should show the number of hog, date and hot dressed weight.
• The carcass is chilled as rapidly as possible. A cooler temperature of (-1⁰C) when hot carcasses are rolled into the cooler will produce an internal temperature of (4.4⁰C) or lower in the ham within 24 hours.
• The carcass and all entrails should be examined to determine whether carcass and all edible offal are fit for human consumption.