A ten-year food preference database (2007–2017) was used to relate food selection in dogs to the nutritional components of diets by doing a principal component analysis (PCA) and a linear regression between components obtained and dogs’ preferences. Intake and preference of preferred diets were analyzed by dogs’ sex, breed, age, body weight, and the season of the year (hot or cold). The fourth component after PCA presented a relation with food preferences (OR = −2.699, p = 0.026), showing negative correlations with crude fiber (rho = −0.196; P = 0.038) and dry matter (rho = −0.184; p = 0.049). Weight (OR = −1.35; p < 0.001), breed, both Boxer (OR = 10.62; p = 0.003) and Labrador Retriever (OR = 26.30; p < 0.001), and season (hot season) (OR = −5.27; p < 0.001) all influenced animals’ intake. Boxers presented a lower food preference compared to the other breeds (OR = −44.3; p < 0.001), while animals’ weight influenced preferences only in Boxers (OR = 2.02; p < 0.001). Finally, age and sex did not affect dogs’ preference or intake of preferred diets. Thus dry matter and fiber content have a negative impact on dogs’ food choices. Dogs’ weight, breed, and season affected food intake, but only breed affected dogs’ preferences, which is probably explained by adaptive changes in the detection, metabolization, and learning of nutritive food cues.

The objective of this study was to develop an encapsulated iron supplement for oral ingestion and to determine its effect on the iron nutrition status of suckling pigs. Encapsulated and non-encapsulated iron supplement was prepared. Seventy-two neonatal piglets were assigned to three experimental groups: (1) parenteral group (gold standard treatment), which received one dose of parenteral iron (200 mg), 2 days of age, (2) “non-encapsulated” group (as a control group), which received 4 oral doses of unencapsulated iron supplement at 2, 7, 12 and 17 days of age, and (3) “encapsulated” group, which received 4 oral doses of encapsulated iron supplement on the same days. The encapsulated and unencapsulated iron supplements contained 65.2 and 65.0 mg/iron/dose, respectively. Parenteral treatment was not sufficient to ensure an adequate iron nutritional state in piglets at the end of the lactation period, showing iron depletion (serum ferritin: 8.4 µg/L). In contrast, oral supplementation prevented the development of iron depletion. Higher serum ferritin values were observed in the encapsulated (19.9 µg/L) compared to the unencapsulated group (17.4 µg/L) (p = 0.020). In conclusion, the use of four oral doses of an encapsulated iron supplement prevents iron deficiency anemia and its previous stages in suckling pigs.

A total of 672 male and female piglets (21 d postweaning; approximately 13 kg BW) were selected to be used in 3 different experiments to assess the influence of dietary electrolyte balance (dEB; Na + K – Cl, in mEq/kg of diet) on feed preference and growth performance. In Exp. 1, piglets were fed 4 isoenergetic diets differing in dEB level: 16, 133, 152, and 269 mEq/kg diets. Changes on dEB were obtained by changing the levels of sodium and chloride with calcium chloride, calcium carbonate, and sodium bicarbonate. Piglets fed the 16 and 133 mEq/kg diets achieved a greater ADG (P < 0.04), BW (P < 0.04), and apparent total-tract digestibility of CP and Zn (P < 0.05) than did piglets fed the 269 mEq/kg diet. The 16 mEq/kg level also reduced blood total CO₂ (P < 0.01), bicarbonate (P < 0.01), and base excess (P < 0.02) concentrations compared with the rest of the dietary treatments. Three diets differing in dEB were designed for Exp. 2 and 3: –16, 151, and 388 mEq/kg diets. In Exp. 2, greater ADFI (P = 0.03), BW (P = 0.02), ADG (P < 0.001), and G:F (P < 0.01) were observed for piglets fed the –16 mEq/kg diet than those fed the 388 mEq/kg diet. Subsequently, their short-term preference for these diets was assessed by using a 2-d choice-test protocol (30 min). Piglets preferred (P < 0.001) the 388 mEq/kg diet to the –16 mEq/kg diet, independently of the dietary treatment they received before. Pigs also preferred (P < 0.001) the 151 mEq/kg diet when compared with the –16 mEq/kg diet. Experiment 3 assessed the long-term preference and short-term consumption of the –16 and 388 mEq/kg diets. Similar to Exp. 2, animals showed a greater (P < 0.001) intake of the 388 mEq/kg diet than they did of the –16 mEq/kg diet during both the preference (14 d) and 1-feeder (2 h) tests conducted. Results show that low rather than high dEB levels optimize growth performance of piglets. When they have the opportunity to choose, piglets are unable to select the diet that optimizes their performance, either in short- or in long-term preference tests, showing also a greater short-term consumption of high instead of low dEB levels.

A ten-year database of food preference tests (n = 1021; period 2007−2017) was used to explore the feeding behavior of domestic cats. Principal component (PC) analysis and linear regression between food nutrients and preferences (for the most preferred diet of each test; Diet A) were performed. Intake and preference for Diet A were analyzed by intrinsic cats’ variables and climate season. The PC1 (calcium (Ca), phosphorus (P), and ash), PC2 (lipids and ether extract) and PC4 (crude fiber; CF) had borderline significance (p < 0.06; β = −1.42, β = −1.56, and β = 2.68, respectively). Ash and CF contents presented negative correlations with food preference (rho = −0.269, p = 0.031; rho = −0.338, p = 0.006, respectively), and Ca had borderline significance and negative correlation with food preference (rho = −0.241, p = 0.054). Body weight and sex influenced the intake of Diet A, being lower for females (β = 11.758; p = 0.014) and heaviest cats (β = −5.490; p < 0.001). However, only body weight affected food preferences, where the heaviest cats had greater preferences for Diet A. Hot season decreased food intake (β = −2,117; p = 0.032), mostly in females (rho = −3.537; p = 0.002). Males had greater preferences for Diet A during hot seasons (β = 10.216; p = 0.023) and females presented similar preferences throughout the year (p = 0.950). Mineral contents, body weight and sex affected food intake and preferences of cats under the influence of climate season, probably explained by adaptive changes in food detection.

Pigs show an innate preference for umami (monosodium glutamate, MSG) taste. Nevertheless, the influence of a pre and postnatal umami exposure remains unclear. An experiment was conducted to test the hypothesis that MSG inclusion into maternal diets would modify the feeding behavior of post-weaning pigs. A total of 22 sows were selected on day 85 of gestation and randomly assigned to one of two gestating and lactating programs (standard commercial diets without or with 50 g/kg of MSG). Later, 208 pigs born from these sows were selected to evaluate their preference thresholds, sensory-motivated intake, total consumption, and consumption patterns for MSG and sucrose solutions. Pigs born from MSG-fed sows showed lower (p < 0.045) preference thresholds for MSG and sucrose than did animals born from control sows, and displayed an increased (p < 0.050) sensory-motivated intake for sucrose and decreased for MSG. Conversely, no differences (p > 0.05) were observed in the total consumption or consumption patterns of MSG or sucrose solutions among pigs born from control and MSG-fed sows. It is concluded that the feeding behavior of nursery pigs can be influenced by pre and postnatal inclusion of a taste active compound into maternal diets. It would appear that a compensatory mechanism to balance dietary nutrients might be in place.