Body Weight: Average body weight of crossbred heifers recorded at the start and then at fortnightly interval during the experiment is depicted in Fig. 1. Irrespective of concentrate and roughage source, average body weight (kg) at beginning and end of the experiment was 116.13 ± 4.74 and 239.47 ± 5.70, respectively. The body weight of heifers increased by 106.21% (123.34 kg), during the experimental period of 168 days. The average body weight (kg) of crossbred heifers that received 40% soyaDOC (T1), 20% soyaDOC + 20% RDDGS (T2) and 40% RDDGS (T3) in concentrate was found to be 177.54 ± 4.63, 178.99 ± 4.35 and 182.32 ± 4.60, respectively. The body weight of T3 group heifers was significantly (p < 0.05) higher as compared to T1 and T2 group heifers, while body weight improved numerically in the T2 group as compared to T1 group. When concentrate source was avoided, body weight (kg) was significantly (p < 0.05) higher in R2 group heifers that were fed wheat straw and groundnut straw mixture (1:1) as compared to R1 heifers that were offered only wheat straw as dry roughage (181.98 ± 3.79 vs. 177.25 ± 3.59 kg). The interaction between concentrate and roughage source (T×R) on body weight was non-significant.
Body weight of heifers increased on replacing soyaDOC with RDDGS in concentrate and in accordance with the findings of Eun et al. (2009) in growing beef steers. They reported that feeding corn-DDGS to beef steer during the growing phase resulted in significant (p < 0.05) improvement in body weight (108 vs. 118 vs. 124 kg). Gibb et al. (2008) observed a non-significant but linear increase in body weight (557.4 vs. 562.4 vs. 567.7 kg) when British cross heifers during the background period received a diet with 0, 20 and 40% of DDGS on diet DM basis. Similarly, Dey (2016) reported numerical improvement in average body weight in crossbred calves (150.90 ± 4.56 vs.159.35 ± 7.41kg) on replacing soybean meal with RDDGS. Eun et al. (2009) in finishing beef steer (182 vs. 191 vs. 186), Manthey et al. (2016) in dairy heifers (264.0 vs. 266.2 vs. 266.4 kg), Chandrika (2018) in buffalo calves (293.09 vs. 302.60 vs. 299.44 kg), Beretta et al. (2020) in steers (457.4 vs. 452.6 vs. 460.9 vs. 465 kg) and Huang et al. (2020) in water buffaloes (401 vs. 393 vs. 408 kg) reported non-significant change in body weight on feeding DDGS. Contrary to present study, Depenbusch et al. (2009) observed irregular change (p ≤ 0.03) in final body weight (483 vs. 494 vs. 483 vs. 474 vs. 473 vs. 458 kg) with increasing level of DDGS in the diet. Increase in body weight of crossbred heifers that received a mixture of wheat straw and groundnut straw (R2) was in agreement with the findings of Desai (2020), he observed significant (p < 0.05) improvement in body weight, when crossbred calves were offered a mixture of wheat and soybean straw over jowar hay (127.89 ± 5.07 vs. 132.80 ± 4.60). However, only numerical improvement in body weight on feeding mixture of cereal and legume straw over cereal straw feeding was reported by AAU (2019) in crossbred calves (237.24 ± 7.80 vs. 211.34 ± 6.08 kg).
Daily Body Weight Gain
Daily weight gain of crossbred heifers was assessed at fortnightly interval during the experiment. Average daily gain (ADG) worked out at fortnightly interval is depicted in the Fig. 2. ADG (g/head/d) of T3 group heifers that received 40% RDDGS in concentrate was 779.9 ± 23.2. It was significantly (p < 0.05) higher than T2 and T1 group heifers that received 20% soyaDOC + 20% RDDGS and 40% soyaDOC in concentrate, respectively. The ADG (g/head/d) in T1 and T2 group heifers was statistically similar (723.2 ± 22.4 vs. 703.9 ± 21.0). Ignoring concentrate source, ADG (g/head/d) of heifers that received a mixture of groundnut straw and wheat straw (R2) was numerically higher than that of heifers offered wheat straw (R1) in ration (751.1 ± 17.9 vs. 720.2 ± 18.6). The ADG of R2 group heifers was 4.29% higher than R1 group heifers however, the difference was non-significant. Interaction of concentrate and roughage source (T×R) on ADG was found to be non-significant.
Improvement in ADG of experimental heifers on replacing full soyaDOC with RDDGS was significant (p < 0.05). A similar finding was reported by Eun et al. (2009) on replacing barley grain with corn DDGS in the diet of growing beef steers. They found a significant increase in ADG (kg/d) between control and DDGS fed steers (1.29 vs. 1.40 and 1.47). Likewise, when Dey (2016) replaced 25% soybean meal in concentrate with 25% RDDGS, the ADG (g/head/d) in calves improved significantly (688.9 ± 29.7 vs. 550.7 ± 16.7). Gibb et al. (2008) in feedlot cattle during background period (0.92 ± 0.06 vs. 0.92 ± 0.06 vs. 0.95 ± 0.03 kg/d) as well as in finishing period (1.46 vs. 1.50 vs. 1.57 vs. 1.54 vs. 1.44 kg/d), Eun et al. (2009) in finishing beef steers (1.62 vs. 1.71 vs. 1.66 kg/d), Manthey et al. (2016) in dairy heifers (0.89 ± 0.071 vs. 0.94 ± 0.083 vs. 0.97 ± 0.083 kg/d), Beretta et al. (2020) in steers (1.50 vs. 1.44 vs. 1.54 vs. 1.62) and Huang et al. (2020) in water buffaloes (1.10 vs. 1.11) reported statistically similar ADG on feedings DDGS in their studies. Numerically higher ADG in experimental heifers that were fed a mixture of groundnut straw and wheat straw (R2) over straw feeding (R1) was parallel with the finding of AAU (2018) in crossbred calves (564.44 vs. 675.56 g/head/d). Whereas, significantly (p < 0.05) higher ADG was reported AAU (2019) in calves (869.23 ± 20.48 vs. 655.57 ± 55.57g/head/d) and Desai (2020) in crossbred calves (522.28 ± 28.68 vs. 597.11 ± 15.84) on feeding mixture of cereal and legume straw during their respective experiments.
Feed Intake
Average dry matter intake (DMI) in experimental heifers assessed at fortnightly interval is depicted in Fig. 3. On avoiding roughage source, average DMI (kg/head/d) of heifers did not change due to feeding RDDGS in T1, T2 and T3 group heifers (4.70 ± 0.07, 4.65 ± 0.06 and 4.71 ± 0.06). Similar finding was reported by Dey (2016) in crossbred calves (3.90 ± 0.09 vs. 4.35 ± 0.09 kg/d) as well as in cows (11.1 ± 0.18 vs. 10.85 ± 0.55 kg/d), Ranathunga et al. (2018) in dairy cows (25.6 vs. 26.1 vs. 25.1 vs. 25.1 kg/d), Beretta et al. (2020) in Hereford steers (10.3 vs. 10.6 vs. 10.6 vs. 11.3 kg/d), Huang et al. (2020) in water buffaloes (8.20 vs. 8.35 vs. 8.42 kg/d) and Fronseca et al. (2021) in Nellore cattle (10.8 vs. 10.7 vs. 10.2 kg/d) on feeding DDGS in their respective feeding trials. Conversely, Gibb et al. (2008) found significant (p < 0.05) and linear increase in DMI (kg/d) in feedlot cattle during finishing period (10.50 vs. 10.7 vs. 11.56 vs. 11.72). Eun et al. (2009) observed significant decrease in DMI on feeding corn-DDGS during background period (8.48 vs. 7.83 and 7.56 kg/d) and finishing period (11.3 vs. 10.5 and 10.4 kg/d) in beef steers. Likewise, Garnsworthy et al. (2020) in dairy cows found linear decrease in DMI (23.1, 23.1, 22.9 and 22.3 kg/d) with significant decrease at 240 g/kg WDDGS level. Depenbusch et al. (2009) found irregular pattern (p < 0.03) in DMI with maximum DMI at 15% DGS diet. The DMI was stimulated when DDGS was incorporated up to 20% of the DM in dairy cow diet. At higher inclusion, decrease in feed intake might be caused by high fat concentration (Council, U. S. 2012). Feeding mixture of wheat straw and groundnut straw significantly (p < 0.05) improved DMI (kg/head/d) in heifers (4.57 ± 0.05 vs. 4.81 ± 0.05). Parallel finding was reported by Desai (2020) in crossbred calves (3.62 + 0.11 vs. 3.47 + 0.13kg/d). AAU (2018) in crossbred calves (5.28 vs. 4.97 kg/d) and AAU (2019) in calves (5.82 ± 0.20 vs. 5.65 ± 0.13 kg/d) reported non- significant change in DMI. However, there was numerical increase in DMI (kg/d) when mixture of cereal and legume straw was fed over cereal straw. The interaction between concentrate and roughage source on DMI (kg/head/d) was also found to be significant (p < 0.05). Highest DMI (kg/head/d) was found in T1R2 group heifers (4.96 ± 0.08) that received 40% soybean meal in concentrate and a mixture of 50% wheat straw and 50% groundnut straw whereas, lowest in T1R1 group heifers (4.45 ± 0.10) that received 40% soybean meal in concentrate and only wheat straw as dry roughage.
DMI (kg/100kg BW) was also calculated at fortnightly interval (Fig. 4) it reduced significantly (P < 0.05) when soyaDOC was replaced with RDDGS (2.66 ± 0.04 vs. 2.59 ± 0.03 and 2.58 ± 0.03). The result was in partial accordance with findings of Dey (2016) who reported numerical decrease in DMI (kg /100kg BW) of cows fed concentrate containing 25% RDDGS (3.26 vs. 3.38). On the other hand, Chandrika (2018) in buffalo calves (2.15 vs. 2.18 vs. 2.16) and Beretta et al. (2020) in steers (2.72 vs. 2.75 vs. 2.75 vs. 2.75) found non-significant change in DMI (kg /100kg BW) when DDGS was included to the diet. Heifers that received a mixture of 50% wheat straw and 50% groundnut straw consumed significantly higher DM (2.57 ± 0.03 vs. 2.65 ± 0.03 kg/100kg BW). This finding was in partial agreement with the finding of Desai (2020) in crossbred calves (2.76 + 0.03 vs. 2.75 + 0.04), all of them found numerical increase in DMI (kg /100kg BW) on feeding mixture of cereal and legume straw to experimental animals. Interaction between concentrate and roughage source on DMI (kg /100kg BW) was also found significant (p < 0.05). Highest DMI (kg/100kg BW) was found in T1R2 (2.75 ± 0.06) and the lowest in T1R1 and T3R1 (2.56 ± 0.05) groups.
Fortnightly DMI (kg/kg BW gain) of experimental heifers is presented in Fig. 5. The average DMI (kg/kg BW gain) of crossbred heifers that received 40% soyaDOC (T1), 20% soyaDOC + 20% RDDGS (T2) and 40% RDDGS (T3) in concentrate was 7.65 ± 0.53, 7.17 ± 0.29 and 6.75 ± 0.30, respectively. There was non-significant differen ce in DMI (kg/kg BW gain) of crossbred heifers fed different concentrate. However, replacement of soyaDOC resulted in linear decrease in DMI (kg/kg BW gain). When concentrate source was ignored, average DMI (kg/kg BW gain) of crossbred heifers of R1 and R2 group was found to be 7.33 ± 0.39 and 7.05 ± 0.22, respectively. There was non-significant difference in DMI (kg/kg BW gain). The interaction between concentrate and roughage source (T×R) on DMI (kg/kg BW gain) was found to be non-significant. Gibb et al. (2008) in British cross heifers (0.134 ± 0.007 vs. 0.135 ± 0.007 vs. 0.137 ± 0.004) during background period and Eun et al. (2009) in finishing beef steers (0.146 vs. 0.165 vs. 0.162) also reported similar gain to feed ratio on feeding DDGS in their studies. Gibb et al. (2008) in finishing period reported linear and significant (p < 0.05) decrease in gain to feed ration with increase in DDGS in diet of heifers (0.140 vs. 0.140 vs. 0.137 vs. 0.132 vs. 0.127). While, Eun et al. (2009) found that gain to feed ratio increased linearly and significantly (p < 0.05) with increases in DDGS in diet of steers during growing phase (0.152 vs. 0.179 vs. 0.195). The DMI (kg/kg BW gain) did not differ statistically when mixture of wheat straw and groundnut straw (R2) was offered to heifer against wheat straw (R1). Though, there was numerical decrease in DMI (kg/kg BW gain) in R2 group heifers. Similar finding was reported by Desai (2020) in crossbred calves. He found significant (p < 0.05) decrease in DMI (kg/kg BW gain), when mixture of cereal and legume straw was offered to crossbred calves (6.93 + 0.31 vs. 9.13 + 0.69).
Thyroid Hormone Profile
Average serum triiodothyronine (ng/mL) of experimental at different days of the experimental period is depicted in Fig. 6. Overall serum triiodothyronine (ng/mL) in heifers, irrespective of treatments and periods was found to be 2.81 ± 0.08. When roughage source was ignored, average serum triiodothyronine (ng/mL) in T1, T2 and T3 group heifers was observed to be 2.69 ± 0.15, 2.81 ± 0.16 and 2.94 ± 0.13, respectively. The serum triiodothyronine (ng/mL) was statistically similar among T1, T2 and T3 group heifers. When the concentrate source was ignored, triiodothyronine (ng/mL) in R1 and R2 group heifers was found to be 2.60 ± 0.10 and 3.02 ± 0.13, respectively. Feeding different roughage source resulted in a significant increase serum triiodothyronine concentration. The serum triiodothyronine (ng/mL) was significantly (p < 0.05) higher in R2 group heifers. The interaction between concentrate and roughage source (T×R) was found to be significant on triiodothyronine level. The serum triiodothyronine (ng/mL) was highest in T3R2 (3.39 ± 0.17) and lowest in T1R1 (2.22 ± 0.15) group heifers. The observed serum average triiodothyronine (ng/mL) in heifers was higher than reported by Periara et al. (2008) in different cattle breeds (2.30 ± 0.07 vs. 1.63 ± 0.07 vs. 1.50 ± 0.10 vs. 2.02 ± 0.07 ng/ml). Pandey (2015) in Tharparker (1.79 ± 0.04) as well as in Karanfries (1.79 ± 0.03) and Baek et al. (2019) in Hanwoo steers (2.24). Conversely, Paulikova et al. (2011) reported higher triiodothyronine level in heifers (3.92 ng/mL) than present study. However, they found lower serum triiodothyronine (ng/mL) in dairy cows (2.28) and calves (1.91).
Average serum thyroxine concentration in heifers at different days during the experimental period is depicted in Fig. 7.The overall average serum thyroxine (ng/mL) in crossbred heifers, irrespective of treatments and periods was found to be 54.12. Average serum thyroxine (ng/mL) in heifers that received 40% soyaDOC (T1), 20% soyaDOC + 20% RDDGS (T2) and 40% RDDGS (T3) in concentrate was found to be 52.20 ± 2.47, 57.86 ± 4.09 and 52.30 ± 2.70, respectively. The serum thyroxine concentration of T1, T2 and T3 group heifers remained statistically similar. On ignoring concentrate source, average serum thyroxine concentration in R1 and R2 group heifers was found to be 54.30 ± 2.16 and 53.94 ± 2.97, respectively. The serum thyroxine concentration also remained statistically similar on feeding different roughage. The interaction of concentrate and roughage source on serum thyroxine level was found to be significant. The heifers of the T2R1 group had the highest (62.29 ± 2.41 ng/mL) and T3R1 had the lowest thyroxine level (47.73 ± 3.97 ng/mL). Average serum thyroxin level in heifers was within the reference range depicted in Clinical Biochemistry of Domestic Animals by Kaneko et al. (2008) in cows (41.58–85.24 ng/mL). Conversely, Periara et al. (2008) in different cattle breeds (82.6 ± 3.8, 65.5 ± 3.8, 69 ± 4.0 and 69 ± 4.0), Paulikova et al. (2011) in heifers (95) and Pandey (2015) in Tharparker (65.03 ± 0.34) as well as in Karanfries (64.32 ± 0.35) observed higher thyroxin concentration (ng/mL) in their respective studies.