By-Products of the Meat Industry

Objectives:

(1) To familiarize the student with the importance of by-products to the meat industry.
(2) To discuss the ultimate uses of edible and inedible by-products in the meat industry.
(3) To show the various uses of animal by-products for the pharmaceutical industry.

Reading material: Principles of Meat Science (2nd Edition), chapter 16, pages 335 to 346.

By-products in the livestock industry are oftentime responsible for the profitability of operating packing plants. A ball-park figure for the contribution of by-products to the value of livestock would be 10% (depending on the specie). The following chart shows the relationship between live weight and carcass components and by-product yields: 

















	Item			Steer		Lamb		Pig









Grade				Choice		Choice		U.S. #1
Live weight, lbs		1000		100		220
Dressed carcass, lbs		600		50		155
Retail cuts, lbs		420		35		125
By-products, lbs	
	Hide or pelt		80		15		--
	Edible fats		110		9		35
	Variety meats		38		3		9		
	Blood			40		5		9
Inedible fats, bone,
 and meat scraps, lbs		175		22		18
Unaccounted items
 (stomach contents,
 shrink, etc.)			140		11		26













Edible meat by-products












Raw by-product			Principal use












Brains				Variety meat




Liver				Variety meat




Heart				Variety meat




Kidneys				Variety meat




Spleen (melt)			Variety meat




Sweetbreads			Variety meat




Tongue				Variety meat




Oxtails				Variety meat




Cheek and head trimmings	Sausage ingredient




Beef extract			Soups and bouillion




Blood				Sausage component




Stomach




 (a) Suckling calves		Rennet for cheesemaking




 (b) Pork			Sausage container, ingredient




 (c) Beef (1st and 2nd)		Sausage ingredient, tripe




Bones				Gelatin for confectioneries, ice cream, and jellied food products




Fats
 (a) Cattle, calves, lambs & sheep	Shortening, candies, chewing gum




 (b) Pork			Shortening (lard)




Intestines, small		Sausage casings




Intestines, large (pork)	Chitterlings




Intestines, large		Sausage casings




Esophagus (weasand)		Sausage ingredient




Pork skins			Gelatin for confectioneries, ice cream, 
				and jellied food products; french fried pork skins




Calf skin trimmings		Gelatin for confectioneries, ice cream, 
				and jellied food products

Inedible meat by-products

Raw by-product Processed by-product Principal use
Hide
(cattle and calves)		 Leather and glue numerous leather goods
paper boxes
sandpaper
plywood
Hair felts
plaster binder
uphostery
Pork skins Tanned skin leather goods
Pelts Wool textiles
Skin leather goods
Lanolin ointments
Fats Inedible tallow industrial oils
lubricants
glycerin
Tankage
Cracklings
Stick		 livestock and poultry feeds
Grease industrial oils
animal feeds
Bones Dry bone glue
hardening steel
Bone meal animal feed
fertilizer
Blood albumen leather preparations
textile sizing
Cattle feet Neatsfoot stock fine lubricants
Neatsfoot oil leather preparations
Glands Pharmaceuticals medicines
Enzyme preparations industrial uses
Lungs pet foods 















Hides, Skins and Pelts













Origin		Classification		Weight, lbs












Unborn calf	Slunk skin		Less than 9




Calf		Light skin calf		9 to 15




		Heavy skin calf		15 to 24




		Kip skin		24 to 31




		Overweight kip skin	31 to 35




Cow		Light cow hide		Less than 53




		Heavy cow hide		Greater than 53




Steer		Extra light steer hide	Less than 48




		Light steer hide	48 to 57




		Heavy steer hide	Greater than 57




Bull		Bull hide		60 to 120 plus




Stag		Accepted as steer or bull depending upon characteristics




Brands




		Native			Unbranded (most valuable)




		Butt branded		Branded on hip




		Colorado branded	Branded on side (least valuable)
















Pelts















Classification			Wool length, inches












Shearlings	1		1/2 to 1




Shearlings	2		1/4 to 1/2




Shearlings	3		1/8 to 1/4




Shearlings	4		less than 1/8




Fall clips			1 to 1-1/2




Wool pelts			greater than 1-1/2

Tallows and Greases

Titer -- congealing or solidification point of the fatty acids in the fat.

Tallow -- fat having a titer above 40 C.

Grease -- fat having a titer below 40 C.

Dry rendering process -- fatty tissues are placed in horizontal, steam-jacketed cylinders equipped with sets of internal rotating blades. Fat cells are ruptured, and the melted fat is released from the supporting tissues. When sufficient moisture has cooked out, the mixture is filtered or strained to remove the cracklings from the rendered tallow or grease.

Animal Feeds and Fertilizers

Dried blood (blood meal) -- made by coagulating fresh blood with steam, draining off the liquid, and drying the coagulum.

Meat meal -- made from the proteinaceous materials from the inedible rendering process.

Steamed bone meal -- made by cooking bones with steam, under a high pressure, in order to remove any fat and meat that may be left on them.

Gelatin and Glue

Gelatin -- made from skins or hides, connective tissues, cartilage, and bones of cattle and calves. Cooking in water converts the collagen in these materials to gelatin.

Glue -- made from the same items as gelatin, but is extracted from these materials by successive heatings in water under specific temperature conditions.

Pharmaceuticals

Glands

Adrenal -- epinephrine is extracted from the adrenal medulla and adrinocortical extract from the adrenal cortex.

Ovaries -- used as a source of estrogens and progesterone.

Pancreas -- yields insulin and trypsin.

Parathyroid -- parathyroid hormone extract is used to prevent large scale muscular rigidity.

Pituitary -- source of ACTH (adrenocorticotropic hormone).

Testes -- source of hyaluronidase.

Thyroid -- source of thyroxine and calcitonin.

Tissues and Organs

Blood -- source of albumin and amino acids.

Bone -- source of calcium and phosphorous.

Intestines -- surgical sutures and condoms.

Liver -- liver extracts and bile extract, which can be used to make cortisone.

Lungs -- heparin

Spinal cord -- source of cholesterol, which is used to manufacture vitamin D.

Stomach -- rennet (from calves), mucin (from pigs), and pepsin (from pigs).

Other by-products

Fetal calf blood -- used for cancer and AIDS research.

Aorta values -- for replacement of defective human heart values.

Fetal pigs -- used for biology teaching.

Gall stones -- sold as aphrodisiacs in the Far East.

Review of Material -- What the student should know:

(1) The versatility of the products obtained from livestock.

(2) The use of various animal products for pharmaceuticals

(3) The value of products obtained from livestock for various industrial uses.

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