Published on Friday, October 26, 2012

Pigs Are Exactly What They Eat

Second in a Series on Pork

As we mentioned in our first article on the pork industry, many things go into raising a quality pig that produces juicy, flavorful pork. Having already discussed the structure of the industry, we now want to turn to the different breeds of swine that are bred together to obtain certain qualities, such as leanness and tenderness, as well as how these animals are fed and housed. 

There are two major categories of swine breeds, paternal and maternal. Paternal breeds are used as boars for swine that will be raised for slaughter, and maternal breeds are used as sows for this purpose. Their offspring result in a mix of different qualities from the boar and the sow, and these are the qualities that farmers are trying to obtain when deciding which pigs to breed together. The paternal breeds have qualities such as meatiness, leanness, and a high growth rate. Breeds include the Duroc, which has sweet meat and marbling that produces amazing shoulders and spare ribs, and the Berkshire, which has tender, juicy meat and a higher fat content, which means thatit can withstand higher cooking temperatures or longer cooking times. The Hampshire is another paternal breed that is heavily muscled and lean, as is the Poland China. Maternal breeds tend to produce more milk, have larger litter sizes, and have a greater mothering ability. The three main maternal breeds are the Yorkshire, Landrace, and Chester White. The Yorkshire is the most recorded type of pig in the U.S. and the Landrace produces, on average, the largest litters of piglets.

Swine nutrition presents the largest cost in swine production, and is composed of four main parts, with a few supplements. Swine need water, energy, protein, and fat as the macronutrients in their diets. They also receive much smaller amounts of minerals to aid in various metabolic processes. The energy source is the largest component of the feed, and corn is generally used to supply this energy. The second biggest part is protein, or more specifically the 10 essential amino acids that pigs need to obtain through their diets. Soybean meal is the only protein source that compares to animal protein in terms of amino acid content and ratio, and thus is most commonly used. Pigs also have some fat in their diet, anywhere from 1-5% of their feed. This is helpful because fat has approximately 2.25 times the energy of most cereal grains and that makes it a more efficient feeding material. However, a proportion of fat over 5% can cause adverse effects to the meat quality, giving it undesirable consistency and taste. Common fat sources include lard, choice white grease, beef tallow, corn oil, and soybean oil. 

The cost of feed required to produce a pound of live hog is 60 to 80 percent of total production costs.  Therefore managing feed use for the benefit of the pig’s health and good meat quality is essential to us getting a good product and the farmer making a living.  To effectively balance the nutrition needs of the pig and the financial needs of the farmer, numerous feeding systems have been developed that allow the farmer to match the types of feeds given to pigs with their life cycle.  For the average pig farm this means having rations to meet 9 to 13 different feeding requirements. 

While each program is somewhat similar in that it contains the macro- and micro-nutrients discussed above, the percentages and volumes of these items can change radically.   For instance, young pigs require 37.5 percent more protein in their diets than do mature hogs.  Proteins can come from many sources and include milk whey, fish meal, soy meal, linseed meal, cottonseed meal, and peanut meal.  Adjusting the percentage of protein to weight of the pig, varying the grain according to price and relative value, and determining the cheapest sources of protein and supplements are management decisions that will affect net returns.   Of course, it is not as simple as it sounds to do this well all of the time and good feed management does require excellent math skills to do correctly.  Just to put a myth to bed, while pigs will eat anything and everything, farmers do not feed them this way.  Science, not the availability of rubbish, dictates feeding protocols.

The production systems used to raise swine can vary greatly and combine several different methods, or variations of those methods, in one farm. We are going to focus on continuous flow vs. “all-in, all-out” systems, as well as pastures, drylots, concrete slabs, slatted floors, and different types of farrowing systems. Each of these systems has advantages and disadvantages, both in terms of economics and animal health. 

In continuous flow systems pigs of all ages occupy different pens in close proximity to one another, which is efficient in terms of time and space, since pigs can be moved to different pens as they grow, and the building is never completely emptied. However, this presents problems with cleanliness and differing levels of disease resistance among pigs of different ages. Higher levels of antibiotics are often used to control disease in this type of operation.  We do not like these systems because of pig health and human health issues.

As a result, most swine are now raised in “all-in, all-out” (AIAO) systems. In this system, all of the pigs in one building are the same age and size, which limits disease spread between older pigs and younger ones with less immunity. The main characteristic of this system is that when one group of pigs is moved out of the building, the entire building is cleaned, sanitized, and left to dry before another group of pigs enters. This is a huge factor in limiting the spread of disease. The disadvantage of this system is that it is more expensive because it is a less efficient use of space. 

A variation of the AIAO system is when different stages of growth happen at totally different sites, which can limit the spread of disease, since contact between pig groups is avoided, but it can cause more stress to the pig from being moved around. Another variation is a “wean to finish” barn where pigs go directly after they are weaned and stay until they are fully grown. The advantage here is that pigs only have to be moved once, which cuts down on stress from moving, and also means that they maintain the same social group, which can be an important factor in stress levels for pigs. After all, pigs are quite social.  Gross, but social.

Mixed in with these two main types of systems are different systems for managing manure. Some pigs are raised in pastures or dry lots, which can work well if the density is low enough to maintain the pasture and incorporate the manure into the soil.  However, most hog operations are bigger than this setup will allow, so it is rarely used today. Another option is a concrete slab floor, which can be completely roofed or partially open. Sometimes bedding such as wood shavings, sawdust or straw is used with this design, but this is less common in warmer climates. Manure is generally scraped from the slab with a skid loader, or handled as slurry. The most common modern design is a slatted floor facility, which is in an enclosed building with a ventilation system. The floor is either partially or completely slatted over manure collection gutters or pits. Manure is quickly separated from the swine because they work it through the slats with their feet. The manure is then pumped out of the pit periodically. 

A final important topic in swine housing is farrowing systems, which are the kinds of pens that sows are put in to give birth and while they are nursing. These systems can be the source of a lot of controversy, particularly when they involve small pens. The smallest of these pens is called a farrowing crate, which significantly reduces sow movement in order to reduce piglet mortality. Piglets, when born, only weigh between 2 and 3.5 lbs., whereas a mature sow can weigh anywhere from 400 to 700 lbs. It does not take much for a sow to lay on one of her piglets and crush it to death. Farrowing crates were designed with this in mind, and in a good farrowing system, can help to keep piglet mortality down to 9%, which is considered very good. Pens that give sows more freedom of movement carry a much higher risk of piglet injury and can cause mortality rates of up to or over 20%. Another farrowing design is a sow pen, which gives the sow more freedom to move, and generally has protection bars that allow the piglets to move away from the sow, though this design still tends to have higher mortality rates. Sows are afforded the most freedom of movement with group housing designs, but there is a much higher piglet mortality rate due to aforementioned reasons as well as to fighting among restless sows prior to farrowing. 

Finding a good balance in animal health, good food quality, and sound environmental practices is always a challenge in this industry and one that we take quite seriously.  Keeping this balance means that we like to work with farmers that follow all the “Best Management Practice” guidance of organizations like Pennsylvania State University to ensure that the animals and the environment are always protected.  We also work closely with Wayne Nell & Sons Meats, to inspect our farms and ensure that these practices are being followed.  Like most of you, this means we like to know that the animals are safe, well fed, and given a little sun.  It also means that we want them to be fed proper rations to maintain their growth and development.  Most importantly, we want them to get the right amino acid balance to be healthy and this does not come from an all acorn diet, no matter what the pop-culture magazines are publishing. 

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Author: Erin Sullivan

Categories: Blog, Education