Page 285 - Small Animal Clinical Nutrition 5th Edition

290 Small Animal Clinical Nutrition

VetBooks.ir intended for reproducing dogs (Chapter 10). nine, or phenylalanine plus tyrosine, is required for maximal
black hair color as for growth (NRC, 2006; Biourge and
Essential Fatty Acids Serheraert, 2002). Other metabolic needs for phenylalanine
Homemade foods with rice and meat as the main ingredients and tyrosine include protein, thyroid hormone and cate-
may not provide enough essential fatty acids for lactation, and cholamine synthesis (NRC, 2006). The minimal recommend-
may need to be supplemented with vegetable oil (Meyer, ed DM phenylalanine allowance for foods for bitches during
1990b). late gestation/peak lactation is 0.83% and 1.23% DM for
phenylalanine plus tyrosine (NRC, 2006). About one and one-
Iron, Zinc and Copper half to two times this much tyrosine is required to maximize
Requirements for most trace elements depend on litter size. black hair color (NRC, 2006).
Hematocrit, hemoglobin and plasma iron values often decrease
in bitches near the end of gestation (Meyer et al, 1985a). Iron
requirements are particularly high during the last week of ges- FEEDING PLAN
tation, when large quantities are stored in the liver of the fetus-
es, and mobilized from the bitch’s body for colostrum (Meyer Generally, recommendations are based on information from
et al, 1985a). Colostrum is very rich in iron; however, levels populations of dogs at similar stages of reproduction. However,
decrease within 48 hours (Meyer et al, 1985a). Iron concentra- the feeding plan should be tailored to meet the needs of indi-
tions are low in mature milk. Because of this, iron requirements vidual dogs based on unique variations in genetics, environ-
increase only slightly during lactation when compared with ment, litter size and health status. Information gleaned from
adult maintenance requirements (Gesellshaft, 1989d). the assessment step (i.e., patient, food and feeding method) sets
Therefore, neonates must have an iron reserve to overcome the the stage for developing the feeding plan; specifically which
initial three-week nursing period, when milk is the only source foods to feed and which feeding methods to use in providing
of food (Meyer et al, 1985a). Latent iron deficiency may impair the food.
neutrophil phagocytic function and cell-mediated immunity,
increasing susceptibility to infections (Bhaskaram, 1988). The Assess and Select the Food
minimum recommended allowance for iron is 70 mg/kg (DM) Food assessment includes a comparison of the current food’s
(NRC, 2006). Oxides of iron should not be used as an iron levels of key nutritional factors with those recommended in
source because they are poorly available (NRC, 2006). Table 15-5. For convenience, Table 15-9 compares the key
During periods when requirements for tissue synthesis are nutritional factor content of selected commercial foods market-
greater than normal (e.g., pregnancy, lactation and growth), ed for dogs during reproduction to the key nutritional factor
animals are particularly susceptible to zinc deficiency. Most targets determined above. Pet food labels usually lack informa-
commercial foods provide adequate zinc. However, if zinc defi- tion about carbohydrate content (other than crude fiber),
ciency does occur during pregnancy, it may lead to fetal resorp- digestibility, energy density and specific vitamins and minerals.
tion or fewer, less viable offspring (Fletcher et al, 1988). The If the food in question is not listed in Table 15-9,it may be nec-
minimum recommended allowance for zinc during essary to contact the manufacturer for information.
gestation/lactation is 96 mg/kg (DM) (NRC, 2006). The food should also be approved by a credible regulatory
Copper is an integral constituent of enzymes that catalyze agency to ensure it will support gestation and lactation (i.e.,
oxidation reactions and plays an important role in connective AAFCO or equivalent). This information should be listed on
tissue formation via lysyl oxidase. It is involved in hemato- the product label. The food assessment step determines the
poiesis because it is a constituent of ferroxidases. It is also a appropriateness of the current food. Food selection involves
cofactor of superoxide dismutase and thus helps protect against choosing the food that most closely fits the key nutritional fac-
oxidative stress. There are numerous sources of copper but tor recommendations. If a food change is warranted, gradually
oxides of copper should not be used because they are poorly transition the bitch to the new food over several days as
available (NRC, 2006). The minimum recommended allow- described in Chapter 1.
ance for copper is 12.4 mg/kg DM (NRC, 2006). Copper Oftentimes foods marketed for gestation/lactation are also
needs during gestation/lactation increase disproportionately to growth-type foods. Thus, they can be referred to as
increased energy needs (Gesellshaft, 1989d). growth/reproduction-type foods. Generally, foods for non-
reproducing sexually intact adult dogs (Table 13-4) will suffice
Phenylalanine and Tyrosine for the first four weeks of gestation (Gesellshaft, 1989a).
Tyrosine is not an essential amino acid but is made from pheny- However, it is probably best to feed a growth/reproduction food
lalanine. However, tyrosine in adequate amounts spares about throughout gestation, particularly for giant breeds.This recom-
half of the need for phenylalanine. Therefore, it is appropriate mendation also negates the need for a food change during mid-
to consider the amount of phenylalanine required as the sum of to late-gestation. Lactation represents an extreme test of a
phenylalanine plus tyrosine. Although phenylalanine and tyro- food’s nutritional adequacy, because no other physiologic
sine are not thought to be the most limiting amino acids for endeavor, other than extreme exercise, requires such a marked
growth in commercial foods, at least twice as much phenylala- increase in energy density and nutrient content (Lewis et al,