Are My Kits Getting Enough Milk?

One of the most common questions I receive from newer rabbit breeders is concern over if their kits are getting enough milk.  This may be due to never seeing the mother nurse her young, as does only nurse their litter once or twice a day, and they are good at doing it when you are not around.  They also rarely ever "check" their nests, which leads many to be concerned that a doe abandoned her litter.  With that in mind however, it is still not uncommon for one or more kits in a litter to not be getting enough milk.  In this article I will describe how to evaluate if kits are getting enough milk and some of the causes as well as solutions to this problem.  I also want to emphasize the importance of being proactive and checking the kits regularly as you can significantly reduce mortality rate by stepping in early when needed.   

There are two initial questions to ask yourself in these situations.
1. Are the kits actually getting the amount of milk they need?
2. If not, is it due to inadequate milk production or inadequate maternal care?

Are the kits actually getting the amount of milk they need?

Well-fed Kits

In well-fed kits, the bellies may range from noticeably round to very large “toad” bellies, white milk can be seen through the skin, kits spend a lot of time sleeping and may also squeak and stir in the box when they sense movement, and mom is lactating well.  

 

Occasionally breeders have the opposite concern that the kits are actually getting "too much" milk.  This is not a cause for concern unless there are other factors at play such as a genetic predisposition for splayed legs in combination with slick floor surfaces, both of which should be avoided.  In my rabbitry, I am always happy to see very big bellies of milk as the kits always thrive.  

These kits are thriving with round bellies full of milk.

______________________________

Under-fed Kits

In under-fed kits, the belly is not round, very little or no white milk will be seen through the skin, the skin may be wrinkled, the kit may be stirring and squeaking quite a bit in the box or may be weak and lack energy, and the kit must be fed soon.  This can also quickly lead to hypothermia.  In older kits, the roundness/fullness of the belly can still be evaluated.

 

This kit has very little milk in its belly and wrinkled skin.

_______________________________

The following tips are with the assumption that the kits are healthy and the only issue is with access to milk.  There are certainly situations where a kit is unhealthy or it may have a genetic issue that prevents it from nursing properly such pituitary dwarfism (peanut).   

Is the mom producing enough milk? 

In my experience, more often than not, the cause of hungry kits is actually an issue with the mom not producing enough milk rather than not taking care of her litter.  

Lactation requires a lot of energy from the mother and she therefore has increased nutritional demands.  Take a moment to look at the NRC nutritional requirements for various stages of rabbit production and check your feed labels to see if you are meeting them.  Lactating does should be fed ad libitum with an increased protein diet of around 17-18% and increased digestible energy.  A rabbit's energy output into milk is very high compared with many other species due to the rate of milk production and richness of the milk that they produce. I have had very good success with supplementing my does' diets during lactation with raw rolled oats which can be purchased from a feed store or grocery store.  I would also recommend feeding a "grow" formula of pellet or something that is formulated for increased nutritional demands such as in lactation.  Be careful with hay quality and quantity during lactation as the nutritional requirements may not be met without carefully supplementing and making sure the doe is consuming enough of the supplement to meet requirements.  If a doe is fed, for example, a diet of Timothy hay and a maintenance pellet during lactation, she will not milk well.  A free PDF of the 1977 NRC Nutrient Requirements of Rabbits can be found here: https://www.nap.edu/catalog/35/nutrient-requirements-of-rabbits-second-revised-edition-1977.

Litter size also plays a role in milk availability as a doe may be producing enough milk for 5 kits, but not for 10.  Feed a doe nursing a large litter really well, but if she still cannot produce enough for all the kits, some or all of them will likely fall behind.  Another interesting consideration (especially with large litters) is the number of teats that a rabbit has (8-10 is average, but they can have 6-12 with independent mammary glands).  Since a rabbit feeds their kits in a very short window of time, there may simply be not enough teats to go around for a large litter.  In these cases, fostering (or grafting) some kits onto another doe that has enough milk is the best option.  I will discuss fostering techniques in the next blog post. 

Heat stress also affects milk production, resulting in lower feed intake and milk yield, so care should be taken to help nursing does stay cool in hot conditions.       

How do you tell if a doe is producing enough milk besides looking at the kits?  Does that are lactating very well will have a pretty pronounced mammary system that you can feel when putting your hand on the doe's belly.  If the area around each teat is raised, that is a good indication of good milk production.

  

This doe is on day 2 of lactation and is lactating extremely well.  You can see and feel the raised mammary glands over her belly.  Many does will not look this pronounced, but will still be lactating sufficiently to raise their litter.  

 

 

You can also express a little bit of milk from the teats to check milk production, especially in animals with less pronounced mammary glands.  You do not want to introduce bacteria when doing this, so clean the area before and after with some diluted iodine and wear gloves.  

 

Occasionally a doe's mammaries can become engorged with a lot of milk that causes her pain.  This often includes the mammary tissue feeling hard and the doe reacting sensitively to touch.  In these situations, the kits can go hungry if not attended to.  Holding the doe while her kits nurse to relieve the engorgement and a warm compress can help alleviate this problem.

 

Although fairly uncommon in rabbits, ruling out mastitis (infection of the mammary glands) is also important.  Symptoms include the mammary area being hot to the touch, fever, and bloody, clumpy, or discolored milk.  If you find signs of mastitis, this will certainly explain kits not getting enough milk and you should consult with your veterinarian for treatment and find another doe to raise the kits or a way to supplement them ASAP.  

Is the mom taking adequate care of the litter?

If no issues are found after evaluating milk production in the mother, it is likely that the doe is not taking adequate care of her kits.  In my experience, this is often in first time moms that are not outrightly rejecting their litter, but are simply not nursing them enough.  I have had good success helping to feed the kits on their mother (which I will cover in more detail in the next post) and the doe's instinct usually kicks in and she takes good care of the kits on her own soon after.

While it is certainly possible to have a doe outrightly reject her litter, I have not run into it personally in 10 years of raising rabbits, likely due in part to the fact that I select for animals that have strong maternal behavior and ensure that they have a stress-free environment to raise their young.  While you may hear about does rejecting litters like it is a common problem, in my experience, so many litter rejections that are talked about are often misidentified with some of the other factors above being the actual source of the problem.  Just because the mom's nest of kits is hungry, doesn't mean she has rejected them.  When a doe is truly rejecting her litter, she will often act aggressively towards the kits.  In these situations, remove the litter ASAP and try to find an alternate way to raise them.

 

Orphans, assisted nursing, fostering, and bottle-raising kits

This will be coming soon in the next post!  

I hope you find this information helpful and please feel free to leave a comment below or send a message with any questions or comments!

Why You Should Reconsider Hay's Place in a Rabbit Diet

With so many feed options out there for rabbits, it can be hard to sort through them and find what is truly best for the health of our animals.  Many sources will recommend a diet of mostly hay (such as the House Rabbit Society recommending it be 80% of their diet and others even recommending 90%) without citing any scientific basis for the nutritive value of their claims.  This type of information gets repeated widely in the rabbit community, ending up in countless articles with continued lack of evaluation of actual nutritional benefit.  "A rabbit's diet should be mostly Timothy hay" is so widely said that it is considered common knowledge to many, but my hope with this article is to prove why it is flawed.   

To preface this article, I want to acknowledge that nutrition in general is such a broad topic with many different strong opinions out there on what is best and what is bad.  Imagine asking 10 random people what the ideal diet for humans is - you will get 10 different answers and many will contradict each other!  It is the same in the rabbit world and I want to emphasize that this entire article is centered around making sure we are providing a diet that meets nutritional requirements, not what specific foods should be fed to meet them with.  This article is not saying that hay is bad, but simply asking the reader to possibly think about hay differently in how it nourishes their rabbits. 

Nutritional Requirements for Age and Productive Status

There is no one-size-fits-all diet for rabbits with nutritional requirements varying by stage of life and production (see table below).  There are certainly other factors impacting nutritional requirements with one example being Angora breeds commonly fed a higher protein feed to support fiber growth (Lebas et al. 2010), so other considerations such as that will impact how to balance the rabbit's diet beyond general recommendations.

Below is a simple table including some of the main nutritional considerations (see sources for more expansive list) for four main stages of life and production.  Included are the recommendations by the National Research Council (NRC) for rabbits in addition to work done by F. Lebas who reported slightly higher nutritional requirements in many situations. 

		Growth	Maintenance	Gestation	Lactation
Digestible Energy (kcal/kg)	NRC (1977)	2500	2100	2500	2500
	F. Lebas (1980)	2500	2200	2500	2700
Crude Fiber (%)	NRC (1977)	10-12	14	10-12	10-12
	F. Lebas (1980)	14	15-16	14	12
Crude Fat (%)	NRC (1977)	2	2	2	2
	F. Lebas (1980)	3	3	3	5
Crude Protein (%)	NRC (1977)	16	12	15	17
	F. Lebas (1980)	15	13	18	18
Calcium (%)	NRC (1977)	0.4	--	0.45	0.75
	F. Lebas (1980)	0.5	0.6	0.8	1.1
Phosphorus (%)	NRC (1977)	.22	--	0.37	0.5
	F. Lebas (1980)	.3	0.4	0.5	0.8

You can see that "maintenance" rabbits have the lowest nutritional requirements.  Maintenance rabbits are rabbits that are fully grown and are not pregnant or raising litters, so pet rabbits would fall under this category as well as adult bucks and does with longer gaps between litters.  Growing kits and pregnant does have similar requirements of more digestible energy and higher protein especially.  Does that are nursing kits have notably higher requirements as well and it is very important to make sure they are meeting these requirements for adequate milk production and to allow the doe to maintain her body condition. 

What happens when these requirement are not met?

While this is by no means an exhaustive list, some symptoms of nutrient deficiency or excess are listed below. 

Nutrient	Deficiency	Excess
Digestible Energy	Weight loss, poor growth, reduced milk production, ketosis, ketoacidosis, fatty liver	Enteritis, obesity, reduced reproduction
Fiber	GI stasis, wool block, enteritis	Reduction in digestible proteins creating an energy deficit
Fat	Dull coat, reduced energy intake, reduced milk yield, reduced vitamin absorption	Reduced growth and reproduction, enteritis, heart disease
Protein	Muscle loss, stunted growth, fatty liver, reproductive disorders	Excess excreted through urine, kidney damage
Calcium	Hypocalcemia, osteoporosis, rickets, impaired zinc and phosphorus absorption	Excess is excreted through the urine which may cause bladder or kidney stones
Phosphorus	Rickets, osteomalacia, infertility, abnormal behavior
Magnesium	Wool block, poor growth, alopecia, convulsions	Excess is excreted through the urine
Copper	Anemia, reduced growth, bone abnormalities, greying of black hair, wool block, enteritis	Copper poisoning
Vitamin A	Infertility, abortion, weak newborn kits, ocular lesions, hydrocephalus	Infertility, abortion, weak newborn kits, hydrocephalus
Vitamin K	Muscle weakness, paralysis, respiratory distress, abortion, placental hemorrhage	Nephritis
Vitamin D	Dental problems, weakened immune systems, cardiovascular problems	Impaired movement, anorexia, infertility
Vitamin E	Reproductive failure, myopathy

Nutritional Content of Hay

Let's look at how hay compares to the nutritional requirements of rabbits above.  Timothy hay, which is very commonly specifically recommended for rabbits, averages only 8% protein which is below requirements for all stages of life and production including a maintenance rabbit.  It also averages 1800kcal/kg of digestible energy which is also below requirements for maintenance.  Alfalfa hay, on the other hand, tends to be 12.9-18% protein depending on maturity which can perfectly meet protein requirements depending on quality of the hay, although the calcium content of alfalfa can be too high at 1.2% on average, causing it to be avoided or limited by many.

Quality of hay makes a huge difference in how nutritious it is.  If you feed packaged hay from the store or buy tested hay, you can check the feed label for nutritional content.  If you feed untested hay, you can try to estimate what it may contain based on the grass/legume content, the quality of the hay, and compare to averages for hay of that type and quality.  When the plant matures past its peak quality, the cell walls become more lignified and increasingly less digestible, especially including a pretty significant drop in protein content after plants move from a vegetative state to seed head production.  You want to look for young, tender leaves, stems that aren't super thick, and less maturity of seed heads in the hay.  You will also want to look for a lot of leaves compared to stems as those are the most nutritious component.  First cutting hay is generally lower quality because the plants grow super quickly in the spring and the weather conditions are often too cool/moist to harvest on time in late spring or early summer, delaying harvest to when the crop is losing nutritive value.  That isn't to say that you can't have a high quality first cutting or a low quality second cutting though, so talk to the farmer, pay attention to how mature the hay looks, and try to get tested hay if possible.  Also, if you have had a particularly wet year, chances are the hay will be lower quality, as farmers have to wait for dry windows of time to harvest with plants growing very quickly in the mean time.

Feeding of Pellets with Hay

Pellets are often what is compared to hay or fed in addition to hay, so important to discuss in this context.  A good quality pellet is composed of mostly "hay" itself (alfalfa, grass, or both) and also is balanced to meet a rabbit's daily requirements including vitamins and minerals.  These pellets are known as "complete" pellets and as the name implies, they are designed to be fed as the complete diet.  It is important to follow the feeding directions on the bag for these pellets, as nutritionists have done the hard work of making sure they contain everything needed for your rabbit to have a balanced diet as long as the pellets are fed as directed.  Most complete pellets will list how much pellet to feed daily according to your rabbit's body weight.  Some hay can be fed on top of that, but if you feed less pellet than the daily recommended serving and replace it with hay, the rabbit is likely not meeting requirements. 

Balancing Diets

Many people feed their rabbits some proportion of both hay and pellets, while some feed veggies and greens, specifically exclude pellets, or feed only pellets, but how do you make sure that your rabbit's diet is meeting its nutritional requirements?  With any feed, the quality of the feed matters.  There are good quality pellets and cheap ones full of fillers, good quality hay and overly mature hay that is so low in nutrition it is like feeding straw, and veggies and greens that offer good nutrients while others offer little at all.  It is important as rabbit raisers that we evaluate the nutritional content of what we are feeding our rabbits and the individual quality of the feed.  If you feed a complete pellet, but only provide a portion of the recommended serving and fill up the rest with Timothy hay, the rabbit will not be getting enough protein and will likely also not be meeting other requirements such as digestible energy and vitamins.  Continuing to use an average 8% protein Timothy hay as the example, the more hay you feed, the richer the rest of the diet needs to be to make up for it.  Half a daily serving of a complete diet and the rest Timothy hay will not provide enough protein, but supplementing with a "concentrate" like grain could help make up for the difference.  Nutrients like vitamins are a lot harder to balance this way and shouldn't be overlooked.   

If wild rabbits eat grass, how can feeding natural grass diet not be providing enough nutrition?

Wild animals instinctually seek out the nutrients that they need.  Besides eating grass and other greens, they also seek out bark, twigs, buds, fruits, seeds, and more.  Every year I see young cottontails licking the gravel in our driveway.  Could they be seeking out salt left behind from the previous winter roads or maybe minerals, I don't know, but the rabbits know that they need something that is there.  This kind of foraging based on the rabbit's own instinct is simply not possible with feeding of domestic rabbits.  Domestic rabbits only have access to the the feed that you provide them in the quantity that you provide as a daily ration.  Where a wild rabbit will select only the tastiest and most nutritious bits of feed and leave the rest, the domestic rabbit only has the quantity provided to eat.  This is why it is so important to make sure that the feed you are providing your rabbit with, whatever feed that may be, is meeting their nutritional demands.

Why feed hay?

During digestion, larger (indigestible) fiber particles are moved through the colon where they are later excreted as hard fecal pellets while smaller (digestible) fiber particles (<0.3mm) are moved through the cecum where they are fermented and excreted as cecotrophs (night droppings) which the rabbit then consumes again.  These larger particles mechanically stimulate motility of the cecum and colon.  Very fine particle size feeds lead to increased retention time in the gut, lowering GI motility.  The question then becomes: how fine is too fine?  Obviously particle size of long stem hay is greater than that of a pelleted feed, but is the particle size of a coarsely ground pellet large enough?  There have been several research studies (some referenced below) on the effect of pellet particle size with somewhat inconclusive results on GI health, but fairly consistent results of increased growth and nutrient utilization by rabbits fed a finer particle feed.  While I don't have an answer to if average pellets contain large enough particle size for optimal GI health, I do know that quite a few rabbit raisers feed pellets exclusively  with no issues.  For someone feeding exclusively pellets, I would personally suggest that they try to find a coarsely-ground pellet or feed just a little bit of long stem hay in addition to the full daily ration of complete pellet.  Pellets manufactured by an extrusion process may also tend to retain longer particle length.   

A common misconception is that hay is required to wear down a rabbit's teeth.  Rabbits have constantly growing teeth, but proper dentition or "bite" is largely genetic and will prevent teeth from overgrowing.  If a rabbit has a bad "bite" the teeth will not get worn down properly even on a diet heavy in hay.  Many rabbit raisers who feed no hay (exclusively pellets) never encounter malocclusion because they breed for proper dentition in their animals.  Müller et al. (2014) studied diet form effect on dental growth and wear and concluded that diet alone is not likely to cause dental problems due to flexible growth that reacts to wear and found no difference between animals fed hay or pellets.   

Hay has value as behavioral enrichment for rabbits, helping to relieve boredom and encourage natural behavior.  While there are many things that can be provided as behavioral enrichment, rabbits do love to chew on and make a mess of hay.  This is an additional benefit of feeding hay outside of nutrition.

Conclusion

While there are many different types of food that can be fed to rabbits, the most important consideration is that the total ration meets the nutritional demands of the rabbit.  Timothy hay which is most commonly recommended for rabbits, in addition to other grass hays, do not contain enough nutrients on their own to meet nutritional demands.  Common recommendations of large quantities of hay in the diet without proper instruction on balancing the remaining nutrients can be very harmful to the health of these animals.  It is very important to balance the nutrients in the entire ration and not just one component of it. 

As always, please feel free to contact me or leave a comment below with any questions or comments! 

-Barbara

References

NRC Requirements for Rabbits: https://www.nap.edu/catalog/35/nutrient-requirements-of-rabbits-second-revised-edition-1977.

Nutritional pathology in rabbits: http://www.caza-narg.ca/ref/ref200806-7.pdf

Digestive disorders: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7149370/

Evaluation of nutritional content of hay: https://extension.usu.edu/rangelands/ou-files/Deter_forage_value_hay.pdf

General Nutrition of Rabbits: https://www.merckvetmanual.com/exotic-and-laboratory-animals/rabbits/nutrition-of-rabbits#v5625687

Nutrient requirements: https://pdfs.semanticscholar.org/0985/0f88ae2a5af2ccd02d41456991b6128dfac0.pdf

Particle size of feed: Vincenzo Tufarelli , Salvatore Desantis , Sara Zizza & Vito Laudadio(2010) Performance, gut morphology and carcass characteristics of fattening rabbits asaffected by particle size of pelleted diets, Archives of Animal Nutrition, 64:5, 373-382, DOI:10.1080/1745039X.2010.496945

Sogunle et al. 2014 - Feed forms of different particle sizes: growth response, carcass yield and intestinal villus morphology of growing rabbits -
Bulletin UASVM Agriculture 71(1) / 2014Print ISSN 1843-5246; Electronic ISSN 1843-5386

Effect of diet on wear of teeth:

Müller et al. (2014) Growth and wear of incisor and cheek teeth in domestic rabbits (Oryctolagus cuniculus ) fed diets of different abrasiveness https://doi.org/10.1002/jez.1864