Nutritional requirements of the dog and cat: gestation and lactation

Both dogs and cats have increased dietary requirements during gestation. The reasons for this are the development of the foetuses and the foetal adnexae, the growth of the uterus and mammary glands, the metabolic activity of the foetuses (which gives rise during the pregnancy to an increased production of heat, the so-called “heat increment”), the effects of the hormone balance (which promotes anabolism and growth, especially towards the end of the gestation) and the energy metabolism of the gravid animal._¹ In addition, the gravid female needs to accumulate stores for the period of lactation to come.

The additional energy and nutrient requirements are relatively small in the early stages of the pregnancy, such that they can be ignored when calculating the rations; the requirements increase as the pregnancy progresses until reaching, in the third trimester, significant levels that must be taken into account when determining rations. In this period the requirements of protein, calcium, phosphorus and other minerals increase considerably over the maintenance levels, while the increase in energy demand is more modest. For this reason, in the last trimester of gestation the ration must supply additional, progressively increasing amounts of energy and nutrients compared to the maintenance needs. As far as concerns the energy requirements, the latest guidelines from the American National Research Council recommended adding a fixed supplement of 26 kcal/kg of body weight to the maintenance requirement during the third trimester of gestation for both dogs and cats._³

Energy requirement during gestation = Maintenance requirement + 26 kcal/kg of body weight

Following delivery, the female starts one of the most demanding periods from the point of view of nutritional requirements, because the production of milk involves a notable increase in the metabolic activity of the animal’s whole body in order to support the extremely intense processes of synthesising the alimentary substances present in the secreted milk. Thus, during lactation the animal’s demand for food increases considerably over maintenance levels and this is manifested not only in those species whose production of milk has been exploited for human alimentation, but also in other mammals. Table 1 summarises the characteristics showing just how energy expensive lactation is in domestic carnivores, precisely because of the concentration of nutrients found in the milk of these species. This concentration is necessary in order to guarantee the growth rates of these species.

Table 1. Chemical composition and energy value of milk from different species in relation to growth rate._^2,4

As far as concerns the energy requirements of the lactating bitch, the equation proposed by the National Research Council_³ takes into consideration the body weight of the bitch, the number of puppies and the stage of lactation, this last because both the quantity and the composition of the milk produced varies during the different stages of lactation._⁵ The suggested equation for calculating the energy needs of the lactating bitch (in kilocalories of metabolisable energy, kcal ME) is the following:

Energy requirement of the lactating bitch (kcal ME) = 145 x body weight^0.75 + body weight x (24n+12m) x L

Where:

• n= number of puppies between 1 and 4
• m= number of puppies above 4
• L= 0.75 for the first week; 0.95 for the second week; 1.1 for the third week; 1.2 for the fourth week.

Throughout the whole period from conception to the end of lactation the body weight and food intake of the bitch undergo considerable changes. In periods of extreme energy demands the food intake is the key to the success of the dietary programme and it is essential to take it into consideration. Fig. 1 illustrates the changes in body weight and food intake in the bitch from conception to completion of weaning the litter.

Fig. 1. Changes in body weight and food intake during gestation and lactation in the bitch.

The equation for calculating the energy requirement of the lactating queen_³ is different:

Energy requirement of the lactating queen (kcal ME) = (100 x body weight_^0.67) + body weight x 60 x L

Where:  L= 0.9 for the first and second weeks, 1.2 for the third and fourth weeks, 1.1 for the fifth week, 1.0 for the sixth week and 0.8 for the seventh week.

As far as concerns the requirements for the other nutrients, these are very similar to those during growth. For this reason, in practice, gestating and lactating animals are fed with commercial foods formulated for growth.

Finally, Table 2 summarises the effects that dietary errors can have on reproductive performance.

Table 2. The effect of dietary errors on reproductive performance.

References

1. Ladetto G. Dispense di Nutrizione ed Alimentazione Animale. CUSL Facoltà di Medicina Veterinaria di Torino (2002).
2. Maynard LA, Loosli JK. Animal nutrition. McGraw-Hill, New York (1969)
3. NRC. Nutrient requirements of dogs and cats. National Academy of Sciences, Washington DC (USA) (2006).
4. Debrekeleer J, Gross KL, Zicker SC. Feeding reproducing dogs. In Small Animal Clinical Nutrition 5^th Ed. Topeka (KA): Mark Morris Institute, 2010; 281-294.
5. Meyer H, Kienzle E, Dammers C. Milchmenge und Milchzusammensetzung bei und Hündin sowie Futteraufnahme und Gewichtsenwicklung ante und post partum. Fortschritte in der Tierphysiologie und Tierernährung (Advances in Animal Physiology and Animal Nutrition); Suppl. No. 16: 51-72 (1985).