The Healthy Herd

In the world of livestock and perhaps especially goats, numerous mineral programs exist. Most folks offer a pre-mixed mineral and supplement lack as needed in the form of additives like kelp or through injections, boluses, gels etc. Some goat owners offer individual minerals free choice. The individual, free-choice programs are based on the idea that goats are nutritionally wise and can select what they need and when they need it. But is that true? How DO ruminants learn what to eat? Here’s what we’ve learned so far.

Taste is the most important factor in deciding, followed by texture and odor. Both formal studies and simple observations have shown that ruminants learn what to eat through social learning (observing and copying dams and herdmates) as well as from biological feedback after consuming those foods. That means that the animal learns primarily through trial and error. If it eats this particular shrub and experiences negative consequences (rumen upset for example) the animal will then, in theory, associate the taste of that shrub with the rumen upset and not eat it again, or at least not eat large amounts of it.

In my research, Dr. Fred Provenza and Dr. Richard Holliday are among the most avid champions of free-choice, individual mineral feeding and nutritional wisdom. Even their observations and studies on the topic illustrated that the animals did not seek out certain minerals until they were deficient, sometimes severely deficient, or imbalanced. This suggests that animals eat to correct, not prevent deficiencies. In a goat-specific study, Provenza concluded “that the relative amounts of different foods ingested within a meal, and the salience of the flavors of those foods, are both important variables that cause goats to distinguish between novel foods that differ in postingestive consequences”  (8). In this study, goats were ate a shrub called blackbrush, both old season growth and current season growth. The current season growth has much lower levels of condensed tannins than old season growth. The animals did not differentiate between the two until they ate more current season growth than old in a meal, enough to acquire an aversion. Yet, taste and odor were still important factors to that acquired aversion. Read the full summary of the study here https://pubmed.ncbi.nlm.nih.gov/24242115/.

Animals do not “instinctively” recognize nutrients, but sodium is dissolved and absorbed so quickly it does appear instinctual. In early studies on nutritional wisdom, sodium was mixed in every mineral that was offered cafeteria-style. Proponents of nutritional wisdom and cafeteria-style mineral programs note this as a flaw and argue that it made it impossible for the animal to “associate feedback from the mineral with its flavor.” – “On Pasture: Can Animals Figure Out What Minerals They Need”.

To date, there are no studies proving ruminants can recognize minerals other than calcium, sodium, and phosphorus. Phosphorus deficiency often results in pica, or a depraved appetite that results in eating odd things like wood, bones, rocks, and even feces. There’s several interesting studies on mineral deficient animals in the sources, including a study in which phosphorus-deficient steers were eating rabbits and one in which calcium-deficient sheep would lick up the urine and feces of the animals in the adjacent pen that were in the non-deficient control group.

In an interesting case I found online, a goat owner fed her animals a popular mineral mix that was very low in zinc and very high in copper (a zinc antagonist) for several years. Animals began dying and were necropsied. Copper toxicity was ruled as the cause of death. What was interesting was that her goats were attempting to eat raw meat that was being fed to her livestock guardian dogs. It was hypothesized the animals were doing so because they were starved for zinc and raw beef is an excellent source of that mineral. To date, I have found no formal study on animals being able to select to correct for zinc deficiency, but that fascinating anecdotal evidence certainly points that direction and is worthy of further study.

Many goat owners believe that perhaps too often in the case of goats, palpability and curiosity trump need – I’ve personally experienced goats developing a taste for toxic plants, including hemlock – goats that were healthy and well-fed with an abundance of other forage and hay available but simply liked the taste of the dangerous plant. The aforementioned research suggests that might be the case sometimes,  perhaps especially in the case of concentrates or tasty treats. Dr. Holliday notes – “I realize mainstream nutritionists tend to downplay or totally reject the idea that animals can self-regulate their nutritional needs. I admit that this ability may not apply to all situations and to every type of feed. Some feed items (grains and concentrates) may be so tasty that most animals would overeat if fed free choice.”

Nutritional wisdom is a fascinating, complex subject worth studying more, but at the moment the evidence points out that the nutritional wisdom of ruminants is limited.

By Kenda Shatswell

Sources:

1. https://onpasture.com/2013/08/12/deer-eat-birds/#!prettyPhoto/0/
2. https://pubmed.ncbi.nlm.nih.gov/18073279/
3. http://www.ucv.ve/fileadmin/user_upload/facultad_agronomia/Producion_Animal/Minerals_in_Animal_Nutrition.pdf
4. https://www.progressivedairy.com/topics/herd-health/holistic-veterinarian-offers-tips-on-free-choice-self-regulating-minerals
5. https://extension.usu.edu/behave/past-projects/sheep-deficiencies
6. https://www.abcplus.biz/images/Catalogs/Dr.%20Holliday%20Joy%20of%20Minerals%20PD858-4.pdf
7. https://onpasture.com/2014/06/23/livestock-foraging-behavior-it-may-not-be-what-you-think/
8. Provenza FD, Lynch JJ, Burritt EA, Scott CB. How goats learn to distinguish between novel foods that differ in postingestive consequences. J Chem Ecol. 1994 Mar;20(3):609-24.

I naively thought nothing bad would ever happen to my pair of does. I hate that it took a tragedy for me to face the reality and responsibility of goat care.

This summer in 2018, I lost my young doe, Scarlett, to listeriosis. Quick and aggressive treatment is critical to the survival of a sick goat.  I believe that Scarlett would have had a better chance of surviving if I had started her treatment a day earlier when she just acted lethargic and was running a fever but was not yet “down”. My vet did not want to give antibiotics until she “knew what she was treating” and wanted to wait until Scarlett showed more specific symptoms. By the time Scarlett was drooling and staggering in circles it was too late. Recovery from listeriosis depends on early, aggressive antibiotic treatment. When signs of encephalitis are severe, death usually occurs despite treatment. Note: Scarlett had the encephalitic form of listeriosis, however there is also a form that causes abortion (miscarriage).

Here is the progress of her illness.

Tuesday, I noticed that Scarlett was sunning on the driveway while Belle was grazing in the backyard. Weird, because they almost always stay within sight of each other.

Wednesday, she was lethargic and would walk a while then lie down. When she walked her back leg(s) seemed to be a little weak. But she did eat some and drink water.  By late afternoon she had gone to the barn and gotten weaker. I called the vet and was asked to get her temp but I didn’t even have a thermometer. I bought a thermometer and called a friend to help. Her temp was 103.8. The vet did not want to prescribe antibiotics without knowing what we were dealing with. BIG MISTAKE.

Thursday:  By the time I woke up Scarlett was drooling profusely. When I was able to get her on her feet she pulled her head sharply to the left and just walked in a circle (hence, the name “Circling Disease). The listeria bacteria infect the brain and, among other effects, can cause paralysis on one side of the face. She was not blinking one eye.

To add to my frustration and panic, my phone reception was terrible, and I had to drive to a nearby restaurant parking lot to be understood. I finally got through to the vet. I had no way to transport Scarlett to her clinic, so she came by and gave her dexamethasone (steroid) for the inflammation in the brain, Banamine (flunixin meglumine) for fever and prescribed Procaine (antibiotic) every 12 hours. But by then it was too little, too late. Even with treatment, she continued to go downhill. I got the supplies to administer subcutaneous fluids, but since she still swallowed I just gave her electrolyte fluids by mouth. Looking back, I wish I had added the sub Q fluids.

Friday: Over the next 24 hours Scarlett grew weaker and weaker. It was heartbreaking to watch. Finally, by Friday afternoon she was almost totally unresponsive, and I accepted the fact that she was not going to make it. I decided to end her suffering. It had been only a little over 48 hours since I knew something was truly wrong with Scarlett. The vet came and put her down. She was very kind and reassured me that I was doing the right thing. She then told me that she had only seen 2 or 3 cases of Listeriosis where the goat survived, and in these cases, it took months of intensive medical care on the part of the owners for the goat to pull through. And, she added, those goats were left with neurological issues. She said she didn’t tell me this at the outset because she could tell I was determined to try to save Scarlett. And, who knows, Scarlett might have been the one goat to beat the odds.  I felt guilty but, given that I had a full-time job, I knew I would not have been capable of that level of care.

Now, to be practical, I wanted to treat Scarlett’s body with respect and love. I anticipated that I might be dealing with this situation even before I had decided to put her down. I had no way to move or bury her by myself and calling friends to do it seemed too much to ask, so I went online and researched pet cremation services. I found one that would come pick her up anytime, not just during weekday working hours, and gave them a call to make sure they would handle a goat when needed. They were so kind and respectful and didn’t seem to think it odd that a woman would want to cremate her pet goat. I called after we put Scarlett down and a wonderful man drove 3 hours round trip to pick her up Friday night. It was an expensive solution, but I was comforted by his kindness.

What I learned from this tragedy:

• Have a plan for handling emergency situations so that you can be calm and rational if/when the time comes. Be prepared with a final plan in case the worst happens.
• Make a list of emergency supplies and keep them on hand.
• Find a vet who can make farm calls if necessary.
• Be informed about the varieties of illness and injury and be firm and proactive in demanding prompt and aggressive treatment.
• Learn what medications are best for treating Listeriosis and other illnesses or injury and plan on having as many of them on hand as you are allowed.

I researched the causes and prevention of listeria infections. For all goat owners I encourage you to do the same. For example, I had always heard not to let your goats eat moldy hay, which I certainly tried not to allow. I figured it might upset their stomachs. Now I have a greater understanding of the true dangers of that and other seemingly picky considerations. The bacteria are all around us can breed in any moist, organic environment, like hay, silage, even grain feed. Standing water can also pose a threat and lord knows we’ve had lots of that with all the rain we had in NC this spring. So far, I have not identified the specific source of Scarlett’s infection, so I am trying to deal with anything I can find.

I have read that there can repeated yearly outbreaks in the same herd during winter-spring when conditions are the most conducive to bacteria growth.

Some recommendations for the prevention of Listeriosis:

• Discard spoiled feed and hay.
• Improve sanitation of pens, water supply, pasture, and housing.
• Keep wild birds away from the herd as much as possible as these birds may serve as vectors for the disease.
• Identify the source of infection in order to help eliminate the causative agent.

By Sarah Simon

Here are some online references:

http://www.aces.edu/pubs/docs/U/UNP-0064/UNP-0064.pdf

http://www.tennesseemeatgoats.com/articles2/listeriosis.html

https://www.merckvetmanual.com/generalized-conditions/listeriosis/overview-of-listeriosis