It’s late winter, and if you haven’t kept your does productive through the winter season, you may be struggling to get them in the mood and doing their jobs now.
There can be a lot of reasons for that, so let’s look at a few of them. I’m going to give you some research excerpts, but you’ll have to do at least some further research for yourselves.
Three common causes of breeding issues this time of year in the U.S. are:
- Resource Allocation and Mobilization
- Day Length and Light Intensity
- Sexual Receptivity
Resource Allocation and Mobilization
Resource allocation is the term given to how rabbit does store energy for use (mobilization) during periods of high energy demand, like lactation.
- When properly raised doelings (those who have never encountered dietary deficiencies, have been healthy, and have been kept in sanitary conditions) have reached 80-85% of their mature size, they will enter the puberty stage of development and be not only capable of conceiving and raising a litter, but will do so without detrimental effect.
That “magic number” does vary a little bit depending on the base genetics, but in my experience it is generally true for most commercial type does with expected maturity weights of 9 to 12 pounds.
Part of that “magic number” includes stored resources. When doelings are allowed a quality, ad libitum diet through the rearing period (from wean to puberty), they will begin to store excess calories as abdominal fat, aka adipose tissue.
This particular fat is actually called perirenal fat and the thickness of it is a well studied factor in rabbit reproduction.
The use of in vivo methods to assess the evolution of fat tissue, such as the perirenal fat thickness method (Pascual et al., 2000, 2004), allowed the description of how females manage their body reserves during reproduction. Although some works have studied the relation of body reserves around parturition and fertility (Rebollar et al., 2011; Romero et al., 2011), no works have described the direct effect of body-reserves mobilisation around partum on the fertility of rabbit females in their subsequent mating. Therefore, the main objective of this work was to describe the dynamic of fat reserves use and its effects on the fertility of primiparous rabbit females. (Savietto et al., 2016)
The does ability to allocate and mobilize resources (store energy and then use it when and how she needs it) is known to be a genetic factor that can be selected for, but it is also affected by the quality of the diet AND the size of the litter she’s rearing.
The growth of young rabbits during the 3 weeks just after birth depends mainly of the milk production from their mother (Szendrö, 2000). Milk production depends particularly of the genetic potential of the doe strain, of the feeding conditions and especially of the size of the suckled litter (Lebas, 1969; Lukefahr et al., 1981; Garcia- Dalmán et al., 2012)
The specific role of diet on not only the does health and performance, but more pointedly on the growth and performance of the litter has been studied as well, although this particular study led to more questions.
Our results suggest that the addition of fat in the doe diet increases the milk intake of kits, which in turn decreases their solid feed intake before weaning. The high milk intake before weaning was found to have a negative effect on the health of young rabbits after weaning when under the same feeding conditions, suggesting an effect on cecal microbiota maturation. Further experiments before weaning to better define dietary preference in suckling rabbits are needed. (Read T. et al., 2016.)
So, what do we do if we suspect that our does have too much internal fat stored, and how does that have anything to do with, well, anything?!
Remember, the fat we’re talking about is perirenal fat, which is located on the outer surface of the kidneys. What is located in close proximity to the kidneys? The ovaries! So, when there is excess perirenal fat, the ovaries and fallopian tubes are often partially or totally obstructed. No matter how willing the doe is to breed, if her eggs can’t get to the fallopian tubes, they can’t be fertilized and the breeding will not result in a litter.
Now, think about WHY the doe has stored that perirenal fat in the first place. It is stored as an energy source during lactation, concurrent lactation and gestation, and even for when her feeder runs dry but she needs calories. Oh, EUREKA! If she’s hungry, she’ll burn that fat!!!
If you have does who just will not breed, or who will breed but are not conceiving, put them on a diet! I have found that reducing their normal feed intake by 50% for ten to fourteen days usually does the trick. I’m a cold-hearted meanie head so I rarely give them “busy work” like hay to keep them busy when they’re hungry, but you certainly can give them rabbit safe chew sticks or horse quality hay to help alleviate their boredom (otherwise, you might find some bowls chewed on or neighbors scratched/bit by grumpy, hungry does). Just remember, the goal is to make them burn up those stored calories.
Because body weight is not necessarily a great indicator of perirenal fat thickness, you simply can’t just weigh the doe and assume she’s good. If she isn’t producing, try a diet; she will probably breed, and conceive, by the time that 14 days is up! Once she breeds, feed her to her appetite (whatever she will actually clean up each day without being frantic for the next meal).
Most of my does eat a standard six weighed ounces of pellets daily when they are not lactating, but I know that because I weigh their feed. You don’t have to weigh feed daily; just weigh a scoop full of feed, and use that for every rabbit. I use a Nutter Butter cookie cup (one of those travel things I get my kids for treats sometimes), which holds six ounces of my feed, or a generic chip dip tub that holds just under twelve ounces if I really cram the pellets in there. Nobody said you had to be all fancy or totally accurate to the last gram! LOL
Day Length and Light Intensity
So when we’ve investigated and addressed resource allocation, what’s next?
The first step should be increasing daylight hours, and maybe even light intensity, via artificial lighting. According to (Eiben et al., 2016):
Comparing 8, 10, 12, 14 or 16 h daily fluorescent lightning with 20 lux light intensity Mousa-Balabel (2011) found that 14 h lighting was optimal for doe performance. Supplemental lighting of 14 h per day with 30 lux light intensity with incandescent bulbs favored productivity when natural photoperiod was decreasing (Mattaraia et al., 2005). Quintela et al. (2001) and Theau-Clément (2007) also found better receptivity and fertility but they increased the day length from 8 to 16 h and used higher, 70 lux light intensity. Theau-Clément (2007) reported reduced weaning weight. Intermittent 12 h daily lighting with 40 lux light intensity reduced rabbit does’ feed intake (Virág et al., 2000). Others assessed the impact of lighting schedule or light colour in rabbit does by the generally used, 30-70 lux light intensity (Gerencsér et al., 2008ab; Kalaba and Abdel-Khalek, 2011). Maertens and Luzi (1995) used higher, 120 lux light
intensity with fluorescent bulbs and increased the day length from 10 to 16 h in preceding 5 days before AI. This lighting schedule resulted in reproduction similar to what they found with 16 h lighting.
According to World Rabbit Science Association
Proceedings 11th World Rabbit Congress – June 15-18, 2016 – Qingdao – China 190 Matics et al. (2015) with 16 h daily lighting, the rabbit does preferred cages with 10-20 lux to those with 150-200 lux light intensity but the number of kits born alive was lower. Besenfelder et al. (2004) studied the effect of 46-97 lux or 210-590 lux light intensity with 16 h daily neon lighting. They observed higher sperm concentration with higher light intensity. Sperm output can be influenced by the duration and source of lighting (El Hammady and Abdel-Kareem, 2015).
In this particular study by Eiben et al., lighting consisting of warm-white neon and cold-white LED with intensity varying from 40 to 50 lux, and durations from 9 to 16 hours were studied in an effort to determine the effect of light duration and intensity on sexual receptivity in artificially inseminated does.
You don’t have to be using AI to gain some valuable information, and suggestions, from this research! In a nutshell, does are more receptive, and therefore more productive, when they get more hours of light each day. But…what is a lux?
A lux is actually a measurement of light intensity, and it is equal to 1 lumen per square meter. We don’t buy light bulbs with lux measurements on the box though, they have lumen measurements. That’s because the lux that a bulb provides is determined by the space it illuminates. A good example to kind of bring this all together is that it requires about 300 lux, in any space, to comfortably read for a prolonged period of time. That’s 6 times the maximum artificial lighting provided the does in this study, so that tells you how little of a change you can make and get results.
LED lighting and photo-stimulation have positive effects on oestrus since pregnancy and kindling rates were increased compared to the values obtained by neon lighting. With the tested LED lighting and LED “dual” photo-stimulation (increased day length and light intensity around AI), the summer production of controlled nursing rabbits can be improved. (Eiben et al., 2016)
Once you’ve dealt with resource allocation, and made any adjustments to daylight hours or light intensity you might need to make, what’s left?
Well, quite simply, is the doe even in the mood? Sexual receptivity can be a pretty common problem, and I am continually astonished at how many folks don’t even check for common receptivity signs before they attempt to breed a doe.
Sexual receptivity is associated with a better fertility (Theau-Clément et al., 2015); possessing a higher number of preovulatory follicles in the ovaries (Kermabon et al., 1994) and higher plasma estrogen concentrations (Rebollar et al., 1992). Also, itis associated with high prolificacy, higher ovulation intensity, fertilization rate, and higher embryo survival (Hoffman et al., 2010).
Basically, does that are receptive are MOST fertile, ovulate better, and conceive more viable embryos. It’s not rocket science folks…if your does are not receptive, you’re not gaining much by trying to force a breeding.
So what are the signs of receptivity? One of the surest ways is to check their vulvas. You really should be doing this before every single breeding attempt as part of a thorough pre-breeding exam…you do not want to breed an unhealthy doe, so those exams can save you a lot of time and money.
Another method that I personally like to use, particularly on virgin does who may just generally be nervous about handling, is the tail tap. The tail tap is super simple to perform, doesn’t require that you pick up, flip, or hold the doe at all, and I have found it to be exceptionally reliable as an indicator of receptivity.
To perform the tail tap, you’ll need to locate the base of the tail bone with the tip of your index or middle finger. The doe should be sitting comfortably. Some does will really tuck their tail when you go fiddling around back there, but I promise, you don’t have to touch anything but that tail bone. You’ll actually be way closer to their anus than their vulva if that makes you feel a little better, lol
Once you locate the base of the tail bone, tap it a few times with your finger tip and watch her tail and hindquarters. If she cocks her tail to one side but doesn’t lift, leave her alone and try again tomorrow. Most will go from tail cocking to lifting sky high within 48 hours.
If she lifts, but not very high, try her with a buck, or try the tail tap again. More often than not she will lift higher within three to twelve hours, or stop lifting altogether. Most of the time, you can decide whether to try her with the buck or give her a few hours by checking her vulva.
- Does who are not at all receptive will have a vulva that is pale/white, and very dry looking.
- Does who are PAST prime receptivity will have a vulva that is very swollen, and very very dark pink to purple, but not very moist looking.
- Does that are at prime receptivity will have vulvas that are moderately swollen, very bright pink, and very moist looking.
Hopefully I’ve included reference information below for every noted study, but if you find one I missed let me know! I’m happy to edit and add it in.
Besenfelder U., Theau-Clément M., Sabbioni E., Castellini C., Renieri T., Havlicek V., Huber T., Wetscher F., Mösslacher G., Brem G. 2004. Effects of different light intensities on quality of spermatozoa in rabbits. World Rabbit Sci., 12, 227-234.
Eiben Cs., Sándor M., Sándor F., Kustos K., 2016 – Effect of photostimulation, light source and season on reproductive performance of rabbit does. Proceedings 11th World Rabbit Congress – June 15-18, 2016 – Qingdao- China,189-192.
El-Hammady H.Y., Abdel-Kareem A.A.A. 2015. Influence of photoperiod and light source on semen characteristics, physiological responses and some blood parameters of rabbit bucks. Egypt. Poult. Sci., 35, 543-555.
García-Dalmán C., González-Mariscal G., 2012. Major role of suckling stimulation for inhibition of estrous behaviors in lactating rabbits: Acute and chronic effects. . Hormones and behavior, 61, 108-113.
Gerencsér Zs., Matics Zs., Nagy I., Princz Z., Biró-Németh E., Radnai I., Szendrő Zs. 2008a. Effect of colour of light on the reproductive performance of rabbit does. In: Proc. 9th World Rabbit Congress, 2008 June, Verona, Italy, 365-369.
Gerencsér Zs., Matics Zs., Nagy I., Princz Z., Orova Z., Biró-Németh E., Radnai I., Szendrő Zs. 2008b. Effect of a light stimulation on the reproductive performance of rabbit does. In: Proc. 9th World Rabbit Congress, 2008 June, Verona, Italy, 371-374.
Hoffman K.L., Hernandez Decasa D.M., Beyer Ruız M.E., Gonzalez-Mariscal G. 2010. Scent marking by the male domestic rabbit (Oryctolagus cuniculus) is stimulated by an object’s novelty and its specific visual or tactile characteristics. Behav. Brain Res., 207, 360-367.
Kalaba Z.M., Abdel-Khalek A.E. 2011. Reproductive performance of rabbit does and productivity of their kits in response to colour of light. Asian J. Anim. Vet. Adv., 6, 814-822.
Kermabon A.Y., Belair L., Theau-Clément M., Salesse R., Djiane J. 1994. Effect of anoestrus and bromocryptine treatment on the expression of prolactin and LH receptors in the rabbit ovary during lactation. J. Reprod. Fert., 102, 131-138.
Lebas F., 1969. Alimentation lactée et croissance pondérale du Lapin avant sevrage. Ann. Zootech., 18, 197-208.
Lukefahr S.D., Hohenboken W., Cheeke P.R., Patton N.M., 1981. Milk production and litter growth traits in straightbred and crossbred rabbits. Journal of Applied Rabbit Research, 4, 35-40.
Maertens L., Luzi F. 1995. Effect of diluent and storage time of rabbit semen on the fertility of does reared under two different lighting schedules. World Rabbit Sci., 3, 27-34.
Maertens L., Lebas F., Szendrö Zs. 2006. Rabbit milk: a review of quantity, quality and non-dietary affecting factors. World Rabbit Sci., 14, 205-230.
Mousa-Balabel T.M. 2011. Using light and melatonin in the management of New Zealand White rabbits. Open Vet. J., 1, 1-6.
Pascual J.J., Cervera C., Blas E., Fernández-Carmona J. 2003. High-energy diets for reproductive rabbit does: effect of energy source. Nutrition Abstracts and Reviews, Series B: Livestock Feeds and Feeding, 73, 27-39.
Read T., Combes S., Gidenne T., Destombes N., Balmisse E., Aymard P.,Labatut D., Bébin K., Fortun Lamothe L., 2016 – Effect of energy level in doe diet on intake and performances of young rabbits before and after weaning. Proceedings 11th World Rabbit Congress – June 15-18, 2016 – Qingdao – China, 439-442 +Poster.
Rebollar P.G., Ubilla E., Alvariño J.M.R., Illera J.C., Silván G. 1992. Influencia del nivel de receptividad sexual sobre el estradiol plasmático y la respuesta ovulatoria durante el postparto en la coneja. Revista Española de Fisiología, 48, 13-18.
Rebollar P.G., Pereda N., Schwarz B.F., Millán P., Lorenzo P.L., Nicodemus, N. 2011. Effect of feed restriction or feeding high-fibre diet during the rearing period on body composition, serum parameters and productive performance of rabbit does. Anim. Feed Sci. Tech., 163: 67-76.