Interactions between mild nutrient imbalance and taste preferences in young ruminants

Forage sources in total mixed rations early in life influence performance, metabolites, and behavior of dairy calves

The objective of this study was to evaluate effects of forage inclusion and sources on performance, metabolism, and feeding behavior of dairy calves. Forty-eight Holstein calves were blocked and randomly assigned to 1 of 4 dietary treatments according to sex and BW at 28 d of life to determine the effects of feeding forage sources (ensiled and dry), with different quality on performance, metabolites, and behavior. Treatments consisted of a no-forage coarsely ground starter (CON); or total mixed ration (TMR) containing 7.5% on a dry matter (DM) basis of Tifton hay of either medium quality (MH) or low quality (LH); or 10% on a DM basis of corn silage (CS). During the first 28 d of life, all calves received 3 L of whole milk twice daily, a commercial pelleted starter and no forage, and water ad libitum. After that, the solid diet was changed to the respective dietary treatments. Calves were gradually weaned from 52 to 56 d of age, and followed for 14 d postweaning. Individual solid feed and milk intakes were recorded daily, and BW and metabolic indicators of intermediate metabolism were recorded weekly. Behavior was recorded, and the analysis was conducted on wk 7 (preweaning) and 10 (postweaning). Solid feed intake increased at wk 7 and 8 when MH, LH, and CS were included in TMR; the same results were observed postweaning. The diets did not affect the average daily gain and BW, but the feed efficiency increased with the CON diet. The β-hydroxybutyrate concentration was greater in calves receiving TMR-containing forage than CON diet. Furthermore, calves supplemented with forage had a greater rumination time. In conclusion, all forage sources included in the TMR showed feed intake and behavior benefits, reinforcing the need for fiber from forage in pre- and postweaning diets.

Pellets Inoculated with Bacillus amyloliquefaciens H57 Modulates Diet Preference and Rumen Factors Associated with Appetite Regulation in Steers

Simple Summary

The probiotic Bacillus amyloliquefaciens strain H57 (H57) may reinforce preferential feeding behaviour by changing ruminal fermentation parameters. Four rumen-fistulated steers were offered feedlot pellets, with (H57) or without (Control, C) the H57 probiotic. Half of the pellets were added to the rumen, at time zero, and half were offered for oral consumption over the next six hours, to make four feeding treatments. Each steer was offered each treatment over time. Each offering was over six days, with rumen fluid sampled over the last three days for a six-hour period per day. A five-minute preference test was performed at the end of each rumen sampling period by simultaneously offering the steers 4 kg of H57 and C pellets. The steers preferred the H57 over the C pellets but the route of offering (rumen versus oral) had no effect on preference. Ruminal pH and molar proportions of iso-butyrate and iso-valerate were higher and ammonia concentrations tended to be greater for H57 compared to C. However, since the route of offering had no effect on preference, the hypothesis, that ruminal fermentation changes take precedence over oral (taste) sensations in driving preference, was not supported.

Abstract

This study examined whether the probiotic Bacillus amyloliquefaciens strain H57 (H57) affects ruminal fermentation parameters that exercise post-ingestive feedback appetite control mechanisms. A 4 × 4 Latin square design was used to separate pre- and post-ingestive effects of H57 in four rumen-fistulated steers. The steers were offered a set amount of feedlot pellets, inoculated with H57 or without H57 (control, C). Half of the total amount of pellets fed were introduced intra-ruminally (r), and then the remaining pellets were orally consumed (o) to make four feeding treatments: H57r/H57o, H57r/Co, Cr/H57o and Cr/Co. Rumen fluid was sampled at 2, 4 and 6 h after feeding. Preference behaviour was tested immediately after the 6 h rumen fluid sampling by simultaneously offering the steers 4 kg of each of H57 and C pellets in adjacent troughs for 5 min. Steers preferred the pellets with added H57 over the C pellets (56:44; p < 0.001) and their preferences were not affected by the treatment protocol imposed to separate post- from pre-ingestive effects (p > 0.05). Steers fed H57 pellets had higher ruminal pH, molar proportions of iso-butyrate and iso-valerate (p < 0.05) and tended to have greater ruminal ammonia concentrations compared to those fed C pellets (p < 0.1). However, post-ingestive signals did not affect diet preference more than pre-ingestive signals.

Low potassium diets with different levels of calcium in comparison with different anionic diets fed to prepartum dairy cows: Effects on sorting behaviour, total tract digestibility, energy metabolism, oxidative status and hormonal response

This study investigated the effects of low potassium diets with different levels of Ca compared to two diets low in dietary cation-anion difference (DCAD) fed prepartum as a strategy to prevent hypocalcemia on sorting behaviour, total tract digestibility, oxidative status and energy and protein metabolism of transition cows. Forty-eight pregnant dairy cows were assigned to 4 treatment groups: Low Ca, low K (LCLK), High Ca, low K (HCLK), Supplementation with anionic mineral mixture (AMS) supplementation with SoyChlor (CAS). After parturition, all animals were fed a standard postpartum diet. Data were collected until 21 DIM. Prepartum urinary pH was significantly reduced by the low DCAD diets, while postpartum Ca homeostasis was affected by the HCLK ration. Feeding AMS induced sorting against particles <1.18 mm in favour of particles >19 mm prepartum. In contrast, cows fed CAS showed an increase in selective consumption of fine particles and sorted against longer particles similar to the HCLK and LCLK groups. Postpartum sorting activity was not affected by the dietary treatments. After calving, apparent digestibility of NDF was significantly reduced in the HCLK group. Prepartum, we observed effects on serum concentrations of non-esterified fatty acids were higher and insulin sensitivity was lower in the AMS group. Blood urea nitrogen (BUN) was decreased in cows fed the CAS ration. Postpartum, we found serum protein to be decreased with the low DCAD diets while BUN was decreased in the CAS group. The low DCAD rations increased prepartum serum malondialdehyde concentrations, while postpartum total antioxidant capacity was lower in the HCLK and the AMS group. From these data, we conclude that AMS decreased prepartum intake due to compromised palatability. Intermediate protein metabolism was affected by the low DCAD diets, while parameters of oxidative stress were probably affected by acid-base balance and Ca homeostasis.

Effects of feeding hay and calf starter as a mixture or as separate components to Holstein calves on intake, growth, and blood metabolite and hormone concentrations

This study investigated how providing hay mixed with calf starter to dairy calves affected their solid feed intake, feed sorting, growth, and plasma metabolite and hormone concentrations. Forty Holstein heifer calves were fed a texturized calf starter (23.4% crude protein, 32.3% starch on a dry matter basis) and chopped Klein grass hay as separate components (CONT) or the same starter and hay mixed at a 90:10 ratio on an as-fed basis (MIX) ad libitum from the date transported to the research farm (4-7 d of life) to 90 d of life. Calves were provided milk replacer (28% crude protein, 15% fat) at up to 557 g/d before the study, 737 g/d from d 14 to 20, 1,105 g/d from d 21 to 41, 737 g/d from d 42 to 48, and 557 g/d from d 49 to 55 on a dry matter basis. calves were fully weaned on d 56. Feed sorting for the MIX calves was evaluated using the Penn State Particle Separator; the sorting index was calculated as the actual intake as a percentage of predicted intake, with values >100% indicating sorting for and values <100% indicating sorting against. Treatment did not affect solid feed intake, growth performance, or plasma metabolite or hormone concentration during the preweaning or weaning periods. However, calves in the MIX treatment had less neutral detergent fiber intake as a percentage of solid feed intake than CONT calves in the preweaning (23.3 vs. 37.0%) and weaning (23.5 vs. 25.8%) periods, although MIX calves sorted (107.2%) for long particles, which were primarily hay, during weaning. During the postweaning period, MIX calves had greater neutral detergent fiber intake as a percentage of solid feed intake compared with CONT calves (23.4 vs. 22.7%), although they sorted against long particles (84.4%), and decreased solid feed dry matter intake compared with CONT calves (3,292 vs. 3,536 g/d) and average daily gain (1.20 vs. 1.31 kg/d). Weaned calves in the MIX treatment also had lower plasma concentration of glucagon-like peptide 2 compared with CONT (0.46 vs. 0.77 ng/mg) but had higher plasma concentrations of ghrelin (0.05 vs. 0.03 ng/mg). These results suggest that feeding a mixture of texturized calf starter and chopped hay at the 90:10 ratio to postweaned calves may decrease solid feed intake and growth.

Acceptance of flavored concentrate premixes by young ruminants following a short-term exposure

Three cafeteria feeding design experiments were conducted to test whether young ruminants have flavor preferences. Experiment 1 was with 11 Dorset × Suffolk weaned lambs of both sexes, aged 5 mo and averaging 47.5 (standard deviation = 5.8) kg of body weight. The lambs were offered a choice of 5 flavored concentrate premixes (FCP) and an unflavored control for 5 min 4 times over 10 d. The FCP were prepared by mixing 200 to 300 g/t (as-is basis) of synthetic flavors (vanilla, milky, spicy/fenugreek, red summer fruits, and molasses) into a basal diet. The unflavored control and the milky flavor were consumed in greater amounts than all other flavors at 83.9 and 65.8 g/test, respectively. The consumption rate of FCP (g/min) was similar among treatments. Lambs spent more time consuming the milky flavor and the control at 123 and 144 s/test, respectively, compared with all other FCP (average of 65 s/test). In experiment 2, 12 weaned female Holstein Friesian calves (56-68 d of age) averaging 75.8 kg (standard deviation = 8.45) of body weight were offered a choice of 4 FCP (vanilla, milky, spicy/fenugreek, and red summer fruits) at an inclusion rate of 150 to 200 g/t (as-is basis) and the unflavored control for 5 min 4 times over 10 d. The average consumption rate was 27.8 g/min, and there were no differences among FCP. In experiment 3, a choice of 4 FCP with 2 different flavor combinations (vanilla-fenugreek and milky-vanilla) included at 75 g/t (as-is basis; low) or 150 g/t (high) was offered to a total of 12 weaned female Holstein Friesian calves (47-62 d of age) with an average body weight of 65.3 kg (standard deviation = 7.91). The FCP were offered daily for 14 d for 30 to 60 min/d. Vanilla-fenugreek (low) was consumed less at 57.5 g/test per calf compared with the other FCP (average of 87.5 g/test per calf). There were no other differences among FCP in experiment 3. Overall, compared with the control, flavors used in the present experiments did not affect feed intake of weaned lambs and calves. Other factors, such as taste, sight, texture of the feed, effect of the dams as previous experience (via maternal ingestion, which influences neonatal feeding), and their interactions, may also play a role in flavor preferences of young ruminants.

Self-selection of plant bioactive compounds by sheep in response to challenge infection with Haemonchus contortus

Plant bioactives can potentially benefit herbivores through their effects on health and nutrition. The objective of this study was to determine the importance of polyphenols and terpenes on the ability of lambs to self-select these compounds when challenged by a parasitic infection and the subsequent impact on their health and productivity. Thirty-five lambs were housed in individual pens and assigned to five treatment groups (7 animals/group), where they received: 1) A basal diet of beet pulp:soybean meal (90:10) (CONTROL); 2) The same diet, but containing 0.3% of bioactive natural plant compounds extracted from grape, olive and pomegranate (BNP); 3) A simultaneous offer of the diets offered to the Control and BNP groups (Choice-Parasitized; CHP-1); 4) The Control diet, and when lambs developed a parasitic infection, the choice described for CHP-1 (CHP-2); and 5) The same choice as CHP-1, but animals did not experience a parasitic burden (Choice-Non-Parasitized; CHNP). Lambs, except CHNP, were dosed with 10,000 L₃ stage larvae of Haemonchus contortus. Infected lambs under choice treatments (CHP-1 and CHP-2) modified their feeding behavior in relation to the CHNP group as they increased their preference for the feed containing polyphenols and terpenes, interpreted as a behavior aimed at increasing the likelihood of encountering medicinal compounds and nutrients in the environment that restore health. This change in behavior corresponded with an improvement in feed conversion efficiency. However, an increased preference for the diet with added plant bioactives did not have an effect on parasitic burdens, hematological parameters, blood oxidation, or serum concentration of IgE.

Invited review: Development and expression of dairy calf feeding behaviour

Miller-Cushon, E. K. and DeVries, T. J. 2015. Invited review: Development and expression of dairy calf feeding behaviour. Can. J. Anim. Sci. 95: 341–350. Feeding and housing practices for dairy calves impact performance and growth early in life, as well as feeding behaviour. There is also increasing evidence that early exposure to different feeding and housing strategies influence the development of feeding behaviour. The dairy calf needs access to milk in sufficient quantities to maintain health and high-levels of growth. In addition, intake of solid feed, such as grain concentrate, is necessary early in life to establish fermentation and develop the rumen. In dairy calves, feeding behaviour patterns can have direct impact on nutrient consumption and, consequently, growth. Further, recent research has provided evidence that behaviour patterns that develop in response to management factors early in life may persist once learned, potentially having longer-term implications for health and welfare. Thus, there is potential for various nutritional, housing, and management factors to impact the learning of feeding behaviour early in the life of dairy calves. This review provides several examples of early management factors that influence feeding behaviour of dairy calves and, in turn, impact calf growth and welfare. For example, providing continuous, ad libitum access to milk results not only in greater growth, but also in meal patterns that more closely resemble the natural behaviour of a calf suckling its dam. Housing management also has the potential to influence when, and how much, a calf eats. Whereas social facilitation promotes intake, particularly at weaning, competition for feed in group-housed calves restricts feeding patterns and degree of feeding synchrony. With regards to provision of solid feed, recent data suggest that providing physically effective hay, in addition to grain concentrate, may be beneficial for the rumen environment and consequent growth and efficiency. However, the physical form and presentation of forage may also influence feeding behaviour of calves, in particular feed sorting, which can impact both immediate nutrient intakes as well as the development and persistence of that behaviour. For example, calves provided hay and concentrate as a mixture begin to sort their feed early in life, with the pattern of sorting depending on hay particle size. Feed sorting in young calves may reflect a motivation to consume a proportion of hay in the diet. In general, it appears to be beneficial for early growth and welfare to support milk and solid feed intake through unrestricted allowances and less-competitive feeding environments. Continued research in this area is needed to assess the longevity of learned behaviour patterns, and what factors may influence their persistence.

Influence of dietary flavours on sheep feeding behaviour and nutrient digestibility

The aim of the present study was to assess whether the feeding pattern displayed by sheep exposed to a monotonous ration is modified when the same ration is presented in a diversity of flavours and if such diversity influences nutrient intake and digestibility. Twelve commercial crossbred wether lambs were assigned to two groups. Six lambs/period (three lambs/group.period) were housed in metabolic crates during two successive periods. One group of lambs (Diversity, D) was fed simultaneously an unflavoured ration of alfalfa, barley, beet pulp and urea (55 : 35 : 9 : 1) and the same ration supplemented (0.2%) with one of the following two flavours: (1) sweet, and (2) umami. The other group (Monotony, M) received only the unflavoured ration. All animals were fed their respective rations ad libitum from 0800 hours to 1600 hours for 26 days in each period. Day 19 was used for assessing the lamb feeding pattern every 30 min for 8 h, and the last 6 days of the period were used for estimating in vivo food digestibility. Lambs in D tended to ingest more acid detergent fibre (ADF; P = 0.10) and to have a lower crude protein digestibility (P = 0.08) than did lambs in M. Nevertheless, average daily DM intake did not differ between treatments (P = 0.22) and lambs in M and D digested the same amount of DM, neutral detergent fibre, ADF and N (P > 0.10). Flavour diversity did not affect N retained, N retained/N consumed, or ruminal pH 1 h after feeding (P > 0.10). Lambs in D showed greater intakes than did those in M during 30 (P = 0.006), 60 (P = 0.02), 90 (P = 0.02), 120 (P = 0.04) and 180 min (P = 0.07) after offering the rations. Results suggest that changes in eating behaviour occurred only during the first part of the feeding period, leading to slight changes in ADF intake and crude protein digestibility, which did not impact nutrient utilisation.

Feeding behavior and ruminal pH of corn silage, barley grain, and corn dried distillers' grain offered in a total mixed ration or in a free-choice diet to beef cattle

Seventy-nine continental crossbred beef heifers (524.4 ± 41.68 kg BW), 16 of which were ruminally cannulated, were used in a 53-d experiment with a generalized randomized block design to assess the effects of barley grain (BG), corn silage (CS), and corn distillers' grain (DG) offered in a free-choice diet on feeding behavior and ruminal fermentation. Treatments were total mixed ration (TMR) consisting of 85% BG, 10% CS, and 5% supplement or free-choice (i.e., self-selection) diets of BG and CS (BGCS), BG and corn dry DG (BGDG), or CS and corn DG (CSDG). Heifers were housed in groups of 9 or 10 in 8 pens and weighed 2 h before feed delivery at d 0, 21, 42, and 52 of the study. Pens were equipped with an electronic feed bunk monitoring system enabling feed intake and feeding behavior to be continuously monitored. Each of these pens was randomly allocated 2 cannulated heifers equipped with indwelling pH probes for continuous measurement of ruminal pH during wk 1, 2, 4, and 7. Blood and rumen contents were taken from cannulated heifers 2 h after feed delivery on d -3, 0, 7, 8, 42, and 49. Cattle fed either TMR or free-choice diets had similar (P > 0.10) ruminal fermentation, blood profile, and growth performance, with the exception of the CSDG diet, for which ruminal pH levels were consistently greater (P < 0.01) and performance was lower (P < 0.01). When DG was a component in free-choice diets, heifers reduced its inclusion in the diet (P < 0.05) over the experiment without affecting growth rate or ruminal fluid pH. Finishing feedlot cattle fed BG and CS separately selected a diet with a greater proportion of BG (85% DMI) compared to the TMR with no signs of acidosis. When cattle were given free-choice access to corn dry DG as an alternative to CS, they consumed levels up to 30% of their total daily DMI. Under the conditions of our experiment cattle can effectively self-select diets without increasing the risk of subclinical acidosis and still maintain similar levels of growth and feed efficiency compared with a TMR.

The effect of palatability of protein source on dietary selection in dairy calves

Evidence has shown that soybean meal is perceived as more palatable than canola meal by dairy calves in short-term preference tests. This study evaluated the effect of protein source on longer-term dietary selection of dairy calves. In experiment 1, 40 Holstein bull calves (11.4 ± 4.3 d of age) were randomly assigned to 1 of 2 choice diets for 6 wk: base starter pellet (S; 12% crude protein; CP) and high-protein pellet (40% CP) containing either (1) soybean meal (SB) or (2) canola meal (CM). In wk 7 to 8, all calves were offered a single pelleted diet containing the protein source to which they were previously exposed. In experiment 2, 22 Holstein bull calves (9.9 ± 4.6d of age) were offered, for 6 wk, a choice of 2 mixed pelleted diets: (1) 70% S and 30% SB (SB mix), or (2) 70% S and 30% CM (CM mix). In wk 7 to 8, calves were randomly assigned to 1 of 2 choice diets, as in experiment 1: (1) SB + S, or (2) CM + S. All feeds were provided ad libitum. Calves received 6 L/d of milk replacer [0.75 kg/d of dry matter (DM)] for the duration of both experiments. Feed intake was recorded daily and calves were weighed every 14 d. Feeds were sampled weekly to analyze DM and nutrient intake. Mixed diets in experiment 2 were analyzed for CP in wk 4 and 6 to assess feed sorting (calculated as actual CP intake as a percentage of predicted intake). In experiment 1, calves offered SB + S in wk 1 to 6 consumed more high-protein pellet than calves offered CM + S [73 vs. 42% of DM intake (DMI)] and, consequently, more CP (168 vs. 117 g/d). Solid feed DMI and average daily gain were similar between treatments. When offered a single diet in wk 7 to 8, calves offered starter containing soybean meal increased intake to a greater extent than calves offered the starter containing canola meal. In experiment 2, calves preferred the SB mix to CM mix (preference ratio: 0.7). Calves consumed more CP than predicted from SB mix in wk 4 and 6 (108 ± 2.0%), indicating that they were sorting in favor of SB. In contrast, calves consumed less CP than predicted from CM mix in wk 4 (81.48 ± 4.1%), indicating that they were sorting against CM. When assigned to choice treatments in wk 7 to 8 of experiment 2, calves offered SB + S consumed more protein pellet than calves offered CM + S (81 vs. 31% DMI) and consumed more CP (378 vs. 196 g/d). Average daily gain was greater for calves offered SB + S but DMI was similar. Overall, these results suggest that dietary selection was influenced by innate feed preferences, and milk-fed calves may not be sensitive to protein imbalances in their diet.

Reduced neophobia: a potential mechanism explaining the emergence of self-medicative behavior in sheep

Gastrointestinal helminths challenge ruminants in ways that reduce their fitness. In turn, ruminants have evolved physiological and behavioral adaptations that counteract this challenge. For instance, emerging behavioral evidence suggests that ruminants self-select medicinal compounds and foods that reduce parasitic burdens. However, the mechanism/s leading to self-medicative behaviors in sick animals is still unknown. We hypothesized that when homeostasis is disturbed by a parasitic infection, consumers should respond by increasing the acceptability of novel foods relative to healthy individuals. Three groups of lambs (N=10) were dosed with 0 (Control-C), 5000 (Medium-M) and 15000 (High-H) L3 stage larvae of Haemonchus contortus. When parasites had reached the adult stage, all animals were offered novel foods and flavors in pens and then novel forages at pasture. Ingestive responses by parasitized lambs were different from non-parasitized Control animals and they varied with the type of food and flavor on offer. Parasitized lambs consumed initially more novel beet pulp and less novel beet pulp mixed with tannins than Control lambs, but the pattern reversed after 9d of exposure to these foods. Parasitized lambs ingested more novel umami-flavored food and less novel bitter-flavored food than Control lambs. When offered choices of novel unflavored and bitter-flavored foods or different forage species to graze, parasitized lambs selected a more diverse array of foods than Control lambs. Reductions in food neophobia or selection of a more diverse diet may enhance the likelihood of sick herbivores encountering novel medicinal plants and nutritious forages that contribute to restore health.

Food sensory characteristics: their unconsidered roles in the feeding behaviour of domestic ruminants

When domestic ruminants are faced with food diversity, they can use pre-ingestive information (i.e. food sensory characteristics perceived by the animal before swallowing the food) and post-ingestive information (i.e. digestive and metabolic consequences, experienced by the animal after swallowing the food) to evaluate the food and make decisions to select a suitable diet. The concept of palatability is essential to understand how pre- and post-ingestive information are interrelated. It refers to the hedonic value of the food without any immediate effect of post-ingestive consequences and environmental factors, but with the influence of individual characteristics, such as animal's genetic background, internal state and previous experiences. In the literature, the post-ingestive consequences are commonly considered as the main force that influences feeding behaviour whereas food sensory characteristics are only used as discriminatory agents. This discriminatory role is indeed important for animals to be aware of their feeding environment, and ruminants are able to use their different senses either singly or in combination to discriminate between different foods. However, numerous studies on ruminants' feeding behaviour demonstrate that the role of food sensory characteristics has been underestimated or simplified; they could play at least two other roles. First, some sensory characteristics also possess a hedonic value which influences ruminants' intake, preferences and food learning independently of any immediate post-ingestive consequences. Further, diversity of food sensory characteristics has a hedonic value, as animals prefer an absence of monotony in food sensory characteristics at similar post-ingestive consequences. Second, some of these food sensory characteristics become an indicator of post-ingestive consequences after their initial hedonic value has acquired a positive or a negative value via previous individual food learning or evolutionary processes. These food sensory characteristics thus represent cues that could help ruminants to anticipate the post-ingestive consequences of a food and to improve their learning efficiency, especially in complex environments. This review then suggests that food sensory characteristics could be of importance to provide pleasure to animals, to increase palatability of a food and to help them learn in complex feeding situations which could improve animal welfare and productivity.