Search Results (16)

This study assessed the effects of using a total mixed ration (TMR), compared to distributing the concentrate and the forage separately, on the productive performance of beef cattle fed high-concentrate diets and on rumen fermentation characteristics, including methane production. Eighteen rumen-fistulated beef calves were fed a concentrate plus pelleted barley straw separately (CS; n = 9) or as TMR (n = 9). Average daily gain and intake of TMR and of straw and concentrate with the CS treatment were recorded. Digestibility was estimated using ashes insoluble in hydrochloric acid as a marker. Rumen liquid and gas samples were obtained, and the abundance of total bacteria, methanogens, protozoa, and anaerobic fungi was analysed. Animals were slaughtered at 500 kg live weight (LW), and dressing percentage and carcass classification were obtained. Another 49 animals for each treatment were used on a commercial farm to exclusively assess animal performance. The treatment (CS or TMR) did not significantly affect (p > 0.05) final LW, average daily gain, carcass dressing percentage, dry matter or digestible organic matter intake, digestibility values, production of methane and carbon dioxide, and abundance of microorganisms in the rumen. However, animals fed TMR had lower rumen pH (5.87 vs. 5.58, p = 0.041 for CS and TMR), suggesting a higher risk of experiencing rumen acidosis than those fed straw and concentrate separately. In conclusion, using a total mixed ration does not seem a suitable strategy to reduce methane production or prevent rumen acidosis in feedlot cattle. Full article

As the key components of dietary carbohydrates, ensuring a balance between forage-neutral detergent fiber (FNDF) and rumen-degradable starch (RDS) is essential for ruminant health. Eight male Hu sheep equipped with rumen cannulas were randomly divided into four groups based on dietary FNDF content: low FNDF (L-FNDF, 6.08%), middle low FNDF (ML-FNDF, 9.47%), middle high FNDF (MH-FNDF, 12.48%), and high FNDF (H-FNDF, 15.68%), while the RDS levels (15.65% of DM on average) were similar among the four groups. A replicated 4 × 4 Latin square design was employed in this study. The results indicated that mean and minimum ruminal pH increased linearly with increasing dietary FNDF content, while the duration and area of pH under 5.8 and 5.6, along with the acidosis index, reduced linearly (p ≤ 0.002). There were no differences between the MH-FNDF group and the H-FNDF group in these indicators (p > 0.05). The molar proportions of acetate, butyrate, isobutyrate, and isovalerate, as well as the acetate-to-propionate ratio, increased linearly, while propionate and valerate molar proportions and lactate concentration displayed a linear decrease with increasing FNDF content in the diet (p < 0.001). Increasing dietary FNDF content extended ruminating and chewing time while enhancing ruminal microbial diversity, promoting the proliferation of Fibrobacterota and Butyrivibrio in the rumen, and improving fiber degradability (p < 0.05). When the dietary FNDF content exceeded 12.48%, no effects of FNDF on acetate to propionate ratio and fiber utilization were observed (p > 0.05). The results suggest that augmenting FNDF content in the PTMR can reshape ruminal fermentation towards acetate production and promote rumination to enhance ruminal pH, thereby alleviating the risk of ruminal acidosis. When the RDS content in the PTMR was 15.57%, an FNDF content of 12.48% was optimal for maintaining stable ruminal function in sheep, and the recommended ratio of FNDF to RDS was 0.8. Full article

Currently, in dairy farming, there is growing concern for the welfare of calves during the critical period between the separation from their dams and weaning. During weaning, rationed feeding is a practice used to improve feed efficiency and control the calves’ growth, but it could also have negative consequences associated with hunger and feed restriction behavior. One such consequence could be the performance by calves of stereotyped behaviors indicative of poor welfare, such as non-nutritive oral behaviors. We hypothesized that making a Total Mixed Ration (TMR) available to calves, in addition to the standard pelleted starter diet, thanks to its structural and nutritional characteristics, could help to focus the oral behavior of the subjects towards nutritional activities and therefore limit the development of stereotyped behaviors, even when the amount of starter is restricted. To test this hypothesis, 30 female Holstein calves (equipped with an accelerometer based on an ear tag), were randomly assigned to one of three treatments: a control diet (CTR) with an ad libitum calf starter but without TMR; Treatment 1 (TRT1) with both ad libitum calf starter and ad libitum TMR; Treatment 2 (TRT2) with ad libitum TMR and a restricted amount of a calf starter (50% of the intake starter of the control group day by day). All animals were kept in individual cages equipped with a slow-flow teat bucket apparatus for milk feeding and with access to separated buckets (one for drinking water, one for the starter, and one for the TMR) placed on the outside of the front gate of each cage. Sucking behavior, as well as resting, ruminating and activity behavior, was recorded individually from 7 days of life to weaning (63 d of age) by an automated monitoring system based on ear-tag accelerometers (SCR eSense, Allflex, Irving, TX, USA). The results showed that in the CTR group, there was a greater sucking activity compared to the TRT1 group (26.25 min/head/day vs. 16.83 min/head/day, p = 0.0181), while the TRT2 group showed intermediate values (20.41 min/head/day). We hypothesized that this increased sucking activity may be explained by the oral activity directed at sucking the Milk Bar tube observed only in CTR calves after complete consumption of available milk and could indicate a higher stress level than in the TRT1 group. The time spent resting was significantly lower for the CTR group compared to the TRT1 group (9.20 h/day vs. 11.15 h/day, p = 0.0049) while the TRT2 group was in an intermediate situation (10.65 h/day). Furthermore, the increase in time dedicated to rest observed in TRT1, in light of the good vitality of the calves shown by the daily patterns of resting behavior and daily activity, also seems to suggest an improvement in welfare conditions compared to calves receiving pelleted starter alone. Based on these results, we can deduce that providing TMR ad libitum in the diet of weaning calves could be an effective strategy to improve calf welfare due to the reduction in stereotyped oral activity. However, further studies are needed to establish threshold values useful for distinguishing physiological from pathological resting times in weaning calves raised in individual cages. Full article

Wear can occur in flat die pelletizers, often reducing service life. This study explores the issue of die hole wear in the pelletizing process of a standard Total Mixed Ration (TMR) feed. The selected TMR formulation comprises varying proportions of corn, alfalfa hay, and quinoa. A coupled DEM-FEM analysis was used to examine stress–strain conditions in various die hole regions at different material ratios, predict the fatigue life of flat die materials in the pelletizing process, and validate the accuracy of investigating flat die wear through friction wear tests. It was found that the entrance of the die hole experiences the most severe conditions in terms of equivalent stress and elastic strain. The fatigue life is shortest at the entrance, with a maximum equivalent stress of 42.8 MPa, a maximum equivalent elastic strain of 2.5 × 10⁻³, and a minimum fatigue life stress cycle of 5.0 × 10⁵. In contrast, the equivalent stress and equivalent elastic strain at the middle and upper parts of the die hole are minimal, with an equivalent stress of 4.8 MPa and a minimum equivalent elastic strain of 2.8 × 10⁻⁴. Material wear tests revealed that the most severe wear on the flat die specimen occurred when the ratio of corn, alfalfa hay, and quinoa straw was 7:2:1, consistent with the findings from the DEM-FEM coupling method. The pelleting process, arising from the contact between the material and metal, encompasses adhesive wear, abrasive wear, and fatigue wear. Full article

The aim of the current study was to evaluate the effect of the starter restriction and of the ad libitum TMR (total mixed ration) inclusion on intake, growth performance, rumination time (RT), and health condition of Holstein dairy calves during weaning. We randomly assigned thirty female Holstein calves (with an average weight of 38.5 ± 1.96 kg at birth) to one of three treatments. From 21 days of age, the calves were fed one of three treatments as follows: a control diet (CTR) with an ad libitum calf starter but without TMR; Treatment 1 diet (TRT1) with both an ad libitum calf starter and ad libitum TMR; Treatment 2 diet (TRT2) with ad libitum TMR and a restricted amount of a calf starter (50% of the intake recorder in the control group day by day). Calves in the TRT2 group, between 56 and 63 days of age, had a lower body weight (80.1; 79.5; 75.6 kg for the CTR, TRT1, and TRT2 groups, respectively) compared with CTR and TRT1 calves. This outcome is ascribed to the average daily gain (0.759; 0.913; 0.508 kg/day for the CTR, TRT1, and TRT2 groups, respectively), resulting also in TRT2 being lower than CTR or TRT1 calves. The inclusion of ad libitum TMR increased the rumination time, especially after weaning (15.28 min/h, 18.38 min/h, and 18.95 min/h for the CTR, TRT1, and TRT2 groups, respectively). Concerning the rumen metabolism and inflammometabolic response, overall, no differences were observed between the three dietary treatments. In conclusion, the results indicated that a TMR could partially replace a calf starter in weaning dairy calves, since neither growth performance nor health status were impaired. In addition, providing TMR (with or without concentrate restriction) led to a better rumen development and likely a better rumen fermentation efficiency in post-weaning. Full article

The hypothesis that adding omega-3 oil to feedlot pellets will improve the meat’s favourable n-3 PUFA composition was tested in this experiment. Therefore, we evaluated the productive traits and modification of the composition of n-3 PUFA of Longissimus lumborum (LL) muscle in growing lambs supplemented with microencapsulated omega-3 oil (MEOIL) in pelleted total mixed rations (TMR). Thirty six one month old Valle del Belice male lambs (14.04 ± 0.1 kg) were randomly distributed to one of the three dietary treatments (n = 12 lambs each) and provided the supplemented diets up to 14 weeks of age: 1. control (CON) pelleted TMR without omega-3 oil supplementation; 2. omega-3 oil fortified pelleted TMR at 1% (MEOIL1) supplementation; and 3- Omega-3 oil fortified pelleted TMR at 3% (MEOIL3) supplementation. Supplementing MEOIL at both levels in diet positively impacted (p < 0.05) body weight (BW) and feed efficiency. At the end of feeding period, most carcass quality traits did not vary significantly (p > 0.05) among groups, with the exception of carcass dressing and loin yield at both levels of MEOIL. The color and physical traits of LL muscle were affected by MEOIL supplementation (p < 0.05), with no significant change in chemical characteristics. Fatty acids composition of meat in term of linolenic, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were significantly (p < 0.05) influenced by both levels of MEOIL. It was concluded that the tested microencapsulated omega-3 oil preparation may be included at 1% in lamb diet for increasing unsaturated fatty acids in meat without any detrimental effects on lamb productivity. Full article

In vitro methods have been standardized and tested to correctly simulate the rumen environment and fermentation process. A few studies have verified that the feed degradability achieved as a result of stirring the samples is higher when the samples are incubated under continuous stirring than when they are only stirred twice daily. The objective of this study has been to verify the effect of the speed of stirring on feed degradability during In vitro incubation. For this purpose, the apparent and true dry matter degradability (ADMD and TDMD) of grass hay, pelleted alfalfa, corn silage, barley meal, straw, and a total mixed ration (TMR) were measured after 48 h of incubation in jars under different rotation speeds. The same types of feed were placed in the four jars of each instrument, and the rotation system of the machine was modified to ensure the simultaneous rotation of a pair of original jars (which sometimes stopped and/or rotated slowly and irregularly) together with a pair of modified jars under regular and continuous rotation. A rev counter data logger was mounted onto the jars, and the rotation speeds of the original and modified jars were measured and compared under different conditions (empty jars, jars with liquid, jars with rumen fluid, and sample bags). The modifications to the instruments stabilized the rotation of the jars, thereby making the stirring more regular during incubation. The degradability was partly influenced by the regular stirring, albeit with just one instrument, and for grass hay, barley meal, corn silage, and TMR. In short, it has been found that the regular stirring of sample bags is not essential to obtain reliable degradability measurement during incubation, although it is better to maintain a constant rotation to ensure a regular and standardized In vitro incubation process and therefore to allow reproducibility and comparisons of the results on feed degradability. Full article

In this experiment, B. subtilis was added to pelletized straw-based total mixed ration, and the rumen microbial diversity of house-fed Duhan hybrid sheep was compared. Ten 3-month-old weaned Duhan hybrid lambs were separated into two groups and fattened for 80 days using a single-factor trial design. During the fattening period, the control and the experiment groups were fed with the same ration, except that the experiment group was supplemented with B. subtilis. The results showed that the addition of B. subtilis could significantly increase the daily weight gain, total weight gain, rumen microbial abundance, and rumen microbial diversity of the Duhan lamb. Among them, the proportion of microbial flora such as Bacteroidetes was significantly increased, producing more acetate, iso-butyrate, and butyrate, obtaining higher energy efficiency. Full article

This study was conducted to examine the effect of a mulberry leaf total mixed ration (TMR) diet on growth performance, apparent digestibility, meat quality and the expression of related meat-quality genes (ADSL, H-FABP) in crossbred black goats. Forty-four Guizhou crossbred black goats (Nubian black goat ♂ × Guizhou black goat ♀), weighing 33.43 ± 0.55 kg, were chosen. The goats were randomly divided into four groups, with 11 test replicates in each group. Group I was the control group and fed with the traditional feeding method of roughage and concentrate supplement without adding mulberry leaf. Group II was fed with a 40% mulberry leaf pellet TMR diet. Group III was fed with a freshly processed 40% mulberry leaf TMR diet. Group IV was fed with a 40% mulberry leaf fermented total mixed rations (FTMR) diet. The results showed that the average daily gain (ADG) of group II was significantly higher than that of group I and III (p < 0.05). The apparent digestibility of group II of ether extract (EE) and neutral detergent fiber (NDF) was significantly higher than that of group I (p < 0.05), and the apparent digestibility of dry matter (DM) and crude protein (CP) was significantly higher than that of group I (p < 0.01). Compared with group I, meat in group II had lower meat color lightness (L*) and yellowness (b*) values (p < 0.01) in the Longissimus thoracis et lumborum. The shear force of group II was significantly lower than that of group I (p < 0.05). The total fatty acids (TFA) of group II was significantly higher than that of groups I and III (p < 0.05), but the total saturated fatty acids (SFA) of group II was significantly lower that than of group I (p < 0.01). Subsequently, the Unsaturated fatty acids (USFA), Monounsaturated fatty acids (MUFA), and Polyunsaturated fatty acids (PUFA) of group II were significantly higher than those in group I (p < 0.01). The contents of total amino acids (TAA), total essential amino acids (EAA), total non-essential amino acids (NEAA) and total of major fresh-tasting amino acids (DAA) of groups II, III and IV were significantly higher than those of group I (p < 0.05), as well as the contents of IMP (p < 0.01). The expression of the H-FABP gene in the arm triceps of group II was significantly higher than that of groups I, III and IV (p < 0.05). The expression of the ADSL gene in the Longissimus thoracis et lumborum and biceps femoris of group II was significantly higher than that of group I (p < 0.05). Collectively, the results of the current study indicated that the mulberry leaf TMR diet improved the growth performance, apparent digestibility and expression of related meat-quality master genes (ADSL, H-FABP) in crossbred black goats, which promoted the deposition of intramuscular fat (IMF) and inosinic acid (IMP) and improved the composition of fatty acids and amino acids in the muscles. Full article

Twenty-four healthy castrated male Holstein growing cattle, with similar body weight (301 ± 11.5 kg), were enrolled in this study and randomly allocated into two groups (12/pen). Holstein growing cattle in the LPT (low NFC/NDF pelleted TMR) group were fed basal pelleted TMR with a low NFC/NDF ratio (NFC/NDF = 1.07), while the HPT (high NFC/NDF pelleted TMR) group were fed with a high NFC/NDF ratio diet (NFC/NDF = 1.71). The results showed that: (1) Body measurements were found to be increased for the LPT group (p < 0.05); compared with the HPT group, feed intake to gain ratio and feed cost in the LPT group were decreased by 12.24% and 15.35%, respectively (p < 0.01). Compared with the HPT group, the LPT group tended to increase chest girth. (2) Digestibility of DM and NDF in the LPT group was higher (p < 0.05) than in the HPT group, being increased by 3.41% and 4.26%, respectively, and increased digestibility of ADF in the LPT group was significant (p < 0.01). (3) The daily feed consumption of NDF in the LPT group was higher than that in the HPT group and the daily rumination time and chewing time in the LPT group were longer than that in the HPT group (p < 0.05). (4) Compared with the LPT group, the parameter of pH, microbial protein and acetate: propionate (p < 0.05) in the HPT group were decreased by 8.57%, 12.46% and 23.71%, respectively. In contrast, the concentration of total volatile fatty acids, acetate and propionate were higher (p < 0.05) in the HPT group, and increased by 13.49%, 19.59% and 52.70%, respectively. (5) Compared with the LPT group, rumen fluid in the HPT group diet up-regulated the mRNA expression levels of BRECs pro-inflammatory factor IL-1β and TNF-α (p < 0.05), and meanwhile, up-regulated the mRNA expression levels of BRECs pro-inflammatory factor IL-6 (p < 0.01); compared with the LPT group, rumen fluid in the HPT group diet up-regulated the mRNA expression levels of CCL28 and CCL20 (p < 0.05) chemokines in CCL types of BRECs; in addition, compared with the LPT group, rumen fluid in the HPT group up-regulated the mRNA expression levels of CXCL2, CXCL3, CXCL9 and CXCL14 chemokines in CXCL types of BRECs (p < 0.01), and the mRNA expression levels of the CXCL5 chemokine tended to be increased (p = 0.06). Full article

Sixty castrated male Haimen white growing goats with an initial age of 100 days old and similar body weight (16 ± 1.5 kg) were selected and randomly allocated into five groups with three replicates in each group with four goats in each pen (5 m × 3.2 m). Goats in the control group (CG) were fed a basal pelleted total mixed ration supplemented with 30% alfalfa hay pellet, while experimental treatments (G6, G12, G18, or G24) were supplemented with four levels (6%, 12%, 18%, or 24%) of GBLR replacing alfalfa hay pellet in the diet, separately. Results showed that (1) the final body weight, average daily gain, and average feed intake of G18 was significantly higher (p < 0.05) than CG; in contrast, the feed conversion ratio of G18 was significantly lower than CG and G12 (p < 0.05); the feed cost per head per day of CG was significantly higher (p < 0.05) than that of G18 and G24, and exhibited obvious linearly decrease (p = 0.04) with increasing GBLR supplementation; and apparent total-tract digestibility of DM and NDF in GBLR treatments were significantly higher (p < 0.05) than CG; (2) alanine transaminase (ALT) concentration in the G18 group was significantly lower (p < 0.05) than those in the control group; aspartate transaminase (AST) concentration in the G24 was significantly lower (p < 0.05) than those in the control group, and an increase in dietary level of GBLR tended to result in a linear decrease (p = 0.09) in the concentration of serum AST; (3) the concentration of malondialdehyde (MDA) demonstrated a tendency to decrease (p = 0.06) linearly with increasing GBLR supplementation; however, glutathione peroxidase (GSH-PX) activity in G12 was significantly higher (p < 0.05) than CG, G6, and G24; in addition, superoxide dismutase (SOD) activity in G18 was significantly higher (p < 0.05) than CG and G6; concentration of immunoglobulin M (IgM), immunoglobulin G (IgG), and immunoglobulin A (IgA) were not affected by GBLR, but increasing dietary GBLR showed a tendency (p = 0.08) to linearly increase the IgG concentration; the content of interleukin 4 (IL4) was significantly higher (p < 0.05) in G12, G18, and G24 than that in CG and G6; (4) There were similar NH₃-N, pH, TVFA, and butyrate for goats fed different levels of GBLR supplementation; the C2 (p = 0.07) and acetate: propionate (p = 0.06) demonstrated a tendency to increase linearly with increasing level of GBLR supplementation, separately; however, it was observed that concentration of propionate showed a tendency to decrease (p = 0.08) linearly in response to GBLR supplementation; and (5) Increasing dietary GBLR tended to linearly enhance the lightness (L*) (p = 0.07) and yellowness (b*) (p = 0.09) values of longissimus dorsi muscles; the redness (a*) value in G18 was significantly higher than that in CG (p < 0.05). Full article

The fatty acid composition for the longissimus dorsi (LD) fat of carcass sheep is a crucial factor impacting meat quality. We performed a 90-day feeding trial of 25 Naemi lambs to investigate the effects of roughage sources (alfalfa or wheat straw) of two sizes (regular and 1 cm chopped) when fed with pelleted total mixed ration (TMR) on the growth performance, fermentation patterns, and fatty acid (FA) composition of longissimus dorsi (LD) fat. Lambs were randomly assigned to individual pens with five treatment diets, as follows: C, control group with TMR; T1, TMR and regular alfalfa hay; T2, TMR and alfalfa hay chopped to 1 cm; T3, TMR and regular wheat straw; and T4, TMR and wheat straw chopped to 1 cm. Four lambs were randomly selected from each treatment (20 total) and sacrificed. LD fat of the carcass was extracted and analyzed for FA using a gas chromatography-mass spectrometry. Significantly increased feed intake was found in T1 and T2. The FA composition of LD fat in T2 had higher unsaturated fatty acid (UFA), omega-6 (n6), and omega-3 (n3) FA content. Conjugated linoleic acid (CLA) and α-linoleic acid were highest in lambs fed T1 and T2. Feeding different types of roughage, especially alfalfa hay, either regular or chopped, with total pelleted mixed ration is crucial to improving feed intake and body weight gain, as it positively enhances the rumen microbial fermentation process by controlling rumen pH. The FA profiles of meat from lambs fed TMR with regular or 1 cm particle size alfalfa hay (T1 and T2) are recommended for human consumption as a source of healthy FAs. Full article

The inclusion of straw in high concentrate total mixed rations (TMRs) of male fattening goats can provide the necessary fiber to prevent ruminal acidosis and maintain growth. The objective of this study was to evaluate the effects of the physical form (PF) of the diet (pelleted vs. conventional) and the straw level (SL) of wheat straw (WS) (15% versus 25%) in total mixed rations on feed intake, growth, total tract digestibility, and blood metabolites of fattening goats. Thirty-two male Beetal goats (27.4 ± 0.28 kg body weight (BW)) were divided randomly into the following four dietary treatments with a 2 × 2 factorial arrangement (n = 8/treatment): (1) CTMR15 (conventional TMR containing 15% WS), (2) CTMR25 (conventional TMR containing 25% WS), (3) PTMR15 (pelleted TMR containing 15% WS), and (4) PTMR25 (pelleted TMR containing 25% WS). Both conventional and pelleted 15% WS TMR had 33.7% neutral detergent fiber (NDF) and 19.3% acid detergent fiber (ADF), whereas in 25% WS TMR the NDF and ADF contents were 38.7% and 22.9%, respectively. The experimental diets were formulated to be iso-nitrogenous (crude protein (CP) = 15%). The dry matter intake (DMI) (1.265 vs. 1.044 kg/day) and average daily gain (ADG) (0.176 vs. 0.143 kg/day) were higher (p < 0.05) in pelleted vs. conventional TMR-fed goats. Irrespective of the PF of the TMR, the 15% WS-fed animals had greater (p < 0.05) DMI (1.206 vs. 1.102 kg/day) and ADG (0.172 vs. 0.144 kg) when compared to those fed on 25% WS diets. Furthermore, feed-to-gain ratio (F:G) was higher (p < 0.05) in the 25% WS-fed goats when compared with the 15% WS-fed animals. Digestibility coefficients, nitrogen balancing, hepatic enzymes, blood metabolites, and hematological parameters were similar (p > 0.05) across all treatments. In conclusion, feeding pelleted TMR with WS improved DMI and growth performance as compared to those fed conventional TMR, and 15% WS performed better than 25% WS without exerting any adverse effects on blood metabolites, liver enzymes, or hematological parameters. Full article

Lysophospholipids (LPL), a new feed additive, were supplemented to a pelleted total mixed ration (TMR) of dairy cows to examine its effects on feed intake, production, and composition of milk and plasma biochemical parameters. Two dietary treatments included diets supplemented without (control diet; CON) or with LPL at a dose of 0.5 g/kg of pelleted TMR. Twelve multiparous, mid-lactation, Holstein cows (Bodyweight 730 ± 9.3 kg; 100 ± 6.0 days in milk) were randomly assigned to one of the two dietary treatments with a 42-day measurement period after a 14-day adaptation period. Feed and water were provided ad libitum. Feed intake and milk yields were recorded daily, blood samples were collected fortnightly, and milk samples weekly. The results showed that the supplementation of LPL did not change feed dry matter intake, milk yields, and milk composition. However, it increased total protein and globulin and the activity of alkaline phosphatase and decreased total cholesterol in plasma. This study suggests that LPL may have beneficent effects in animal health but might be not a feasible feed additive to increase production for dairy cows fed a pelleted TMR. Full article

This study evaluated the effects of hay-based total mix ration (TMR) in pelleted or unpelleted form on intake, weaning age, performance parameters, blood metabolites, and cost-effectiveness in crossbred dairy calves during the preweaning period under hot climatic conditions. Thirty calves (4 ± 1 days (d) old), were assigned to one of the three dietary treatments in a randomized complete block design. Treatments assigned were: (1) conventional calf starter (CCS); without hay (2) TMR containing 85% calf starter and 15% chopped oat hay (OH) and (3) pelleted TMR (PTMR) containing 85% calf starter and 15% OH. Colostrum-fed calves were offered four liters (L) of whole milk each, during the first week, followed by six L daily. Calves were weaned off milk gradually on the basis of targeted starter intake of 200, 600, and 800 grams, after which they were considered weaned. Environmental temperature, feed intake, and health scores were recorded daily. The calves experienced heat stress with an average temperature-humidity index (THI) of 80.06 ± 3.42. Results revealed that average daily dry matter intake (DMI), average daily gain (ADG), and feed efficiency (FE) were not different (P > 0.05) among the treatments. Changes in body measurements, rumen development parameters, and blood metabolites were also not affected by the treatments (P > 0.05). Average weaning age in PTMR was 5.4 d earlier as compared to CCS. Feed cost per unit gain tended to be lower for PTMR compared with CCS-fed (86%) calves. Feeding pelleted TMR containing 15% OH tended to reduce the weaning age and feed cost per unit gain without affecting growth performance, intake, FE, and health parameters in crossbred calves under heat stress conditions. Full article