Mixed rations provide ruminants with a balanced diet by aiming to prevent selective feeding. However, this is a natural behavior of sheep and goats based on their dietary needs and the nutritional properties of feedstuffs. Therefore, the present study investigates non-lactating dairy sheep's and goats' acceptance of a mixed ration when it is offered as choice next to its single components. Because all offered feeds were of comparable nutritional value, the animals were expected to not show a particular preference. Twelve pairs of sheep and goats each, were offered three different feeds simultaneously for 5 replicate days. Two feeds consisted of a single component, hay (H) or grass-silage (G) of similar nutritional value. The third feed was a mixed ration (M) including both single-feed components in a 50:50 dry matter (DM) ratio. Feeds were offered ad libitum twice daily. The animals' intake of each feed was recorded at six time points per day by weighing the leftovers. Feed preference was expressed as the natural logarithm of the ratio of the intake of the single component to the intake of M and analyzed using linear mixed-effects models. Additionally, the animals' first choices after gaining access to the feeds were recorded at each weighing event and analyzed using an item response tree generalized mixed-effects model. The sheep's average daily DM intake was 59 (±11)% G, 26 (±10)% H, and 15 (±10)% M (mean ± standard deviation). Goats consumed an average of 56 (±13)% G, 37 (±12)% H, and 7 (±6)% M daily. Both species preferred the single components to M in all observation periods. The proportions of the three feeds consumed differed throughout the day and between species. For both species, the estimated probability that an animal chooses a single component over M first was over 94% at all time points. These results show that, contrary to our expectations, non-lactating dairy sheep and goats prefer single components over a mixed ration of the same components and similar nutritional value. This might be caused by the animals seeking to diversify their feed throughout the day independent of apparent nutritional values and/or because sensory properties of the single components, indicating palatability, are relevantly reduced by mixing.IntroductionThe use of mixed rations played a major part in the intensification of beef and dairy cattle production in recent decades (1). Mixed rations are fed as partial mixed rations (PMR) or total mixed rations (TMR). In PMRs, usually, roughage feed components are mixed and other components, such as concentrates, are offered separately. TMRs, on the other hand, contain all ingredients of the diet, including minerals and concentrates. Feeding livestock mixed rations is labor-efficient, reduces feed refusal, and provides nutritional advantages for the animals (1). Mixing components allows to combine less palatable feedstuffs with more palatable ones into a balanced diet and to easily adapt to various production levels (1). Mixed rations also enable all animals in a herd to access the same feed by preventing individual animals from monopolizing access to preferred feedstuffs (2) such as concentrates (3). Additionally, mixed rations reduce sorting for feed components in cattle (1), resulting in more consistent feed quality over time. This increases feed intake, especially for animals that reach the feed later than others in the herd (4), thus increasing animal productivity and feed efficiency (5).In small ruminants (sheep and goats), the use of mixed rations is not yet as widespread as in cattle. However, the general worldwide trend toward fewer farms with larger herd sizes suggests that this labor-efficient feeding system will also be increasingly used for small ruminants. The effects of feeding mixed rations on productivity in small ruminants have been investigated, but the results are less consistent than for cattle. Monzón-Gil et al. (6) demonstrated that TMR feeding increased feed intake and milk yield in goats compared to single component feeding. Görgülü et al. (7) found that goats freely choosing the ratio of feed components (of the compared TMR) showed higher dry matter intake and higher milk yield than TMR-fed goats, although milk production efficiency was better on the TMR diet. In contrast, Yurtseven et al. (8) found that in sheep TMR feeding had no effect on milk production performance compared to free-choice feeding with the feeds of the compared TMR.To better understand the effects of mixed-ration feeding in small ruminants, it is necessary to consider these animals' distinct feeding behavior. The ancestors of sheep and goats evolved predominantly in harsh environments and thus developed very selective foraging and feeding behaviors as an adaptation to seasonal and local variations in the availability of feed plants (9). Domestic sheep and goats kept in natural and semi-natural environments use selective browsing to adapt their intake to their nutritional needs (9–11). Sheep and goats also sort components of a feed (12) and choose among different feeds in indoor feeding conditions according to the varying nutritional needs of their current physiological stage (12). Therefore, it is unclear whether mixed rations are appropriate for sheep and goats as these rations are explicitly designed to limit selective feeding (13).Previous studies have found that sheep and goats select their feed based on nutritional aspects in order to obtain a diet that meets their nutritional requirements. For instance, sheep and goats have both shown a preference for forages with higher organic matter digestibility and lower fiber content, preferring, for example, leafy grass hay to mature grass hay or straw (14). In short-term preference tests (3 min sessions), goats' feed choices were more influenced by the type of starch than by forage-to-concentrate ratios; they preferred starches that degrade rapidly in the rumen to those that degrade slowly (15). In a three-week feeding experiment, sheep ate more feeds supplemented with NaHCO3 than unsupplemented feeds (16). Goats have also been shown to adapt their concentrate intake based on its crude protein concentration, eating less soybean-based concentrate (which is high in crude protein content) than chickpea-based concentrate (which is lower in crude protein), leading to a consistent percentage of crude protein intake in the total diet (17).Additionally, small ruminant adapt their feed intake and choices based on what feeds they have already consumed. It is assumed that they do this by monitoring the current condition of the rumen (18). For example, sheep's consumption of low-energy-density feeds depends on the carbohydrate sources of other feeds consumed (16). Thus, although small ruminants prefer energy-dense feeds (19), they apparently substitute their diet with feedstuff higher in fiber contents if necessary to balance the ruminal pH (20). This might explain why free-choice-fed goats prefer different feeds at different times of day (7). When foraging in natural and semi-natural environments both species prefer different plant species when the available variety is not restricted (11). But for harvested feeds of restricted number of options [six forages (14)] and for artificially flavored feeds (21) sheep and goats show similar preferences.Based on the studies described above, one would expect that sheep and goats will not show a preference for a particular feed if all offered feeds meet the animals' nutritional requirements and are comparable in terms of properties such as energy density and fiber content. Therefore, the aim of this study was to assess non-lactating dairy sheep's and goats' acceptance of a mixed ration when the single components of that ration, grass silage and hay, are offered at the same time. All three feeds (mixed, grass silage, and hay) had similar nutritional value and met the animals' nutritional needs. We therefore hypothesized that, on average, all three feeds would be consumed by both species in similar amounts regardless of the time of day.