Inuence of Feeding Rice DDGS and Mixture of Wheat Straw and Groundnut Straw on Growth, Feed Intake and Thyroid Hormone Prole of Growing Crossbred Heifers

Present experiment was carried out at Livestock Research Station, CVSc & AH, AAU, Anand, Gujarat (India) on twenty-four HF×Kankrej heifers with average body weight of 116.13 ± 4.74 kg and an average age of 281.92 ± 13.26 days to study the effect of feeding rice DDGS and mixture of wheat straw and groundnut straw on growth, feed intake and thyroid hormone prole of growing crossbred heifers. Three different concentrates containing 0, 20 and 40% rice DDGS (RDDGS) were offered to T1, T2 and T3 group heifers, respectively. RDDGS was given in place of soyaDOC in concentrate. Under each concentrate type, half of the heifers were offered wheat straw (R1 group) and another half a mixture of wheat straw and groundnut straw (R2 group) as dry roughage. The protein requirement of heifers was fullled as per ICAR (2013). Body weight was recorded at start and then at fortnightly, feed intake was calculated from the records of daily feed consumption and thyroid hormone prole was done in serum samples collected at start and then at 28 days interval throughout the experiment. Prior permission was taken from institutional animal ethics committee (IAEC, Project: 313/LPM/2019). The recorded data during the experiment was statistically analyzed by RBD factorial design. When roughage source was ignored, body weight of T3 group heifers was found signicantly (p < 0.05) higher compared to T1 and T2 group heifers (182.32 ± 4.60 vs. 177.54 ± 4.63 & 178.99 ± 4.35).On avoiding concentrate source, body weight (kg) was signicantly (p < 0.05) higher in R2 group heifers as compared to R1 heifers (181.98 ± 3.79 vs. 177.25 ± 3.59 kg). ADG of T3 group heifers (779.9 ± 23.2 g/head/d) was signicantly (p < 0.05) higher than T2 and T1 group heifers (723.2 ± 22.4 vs. 703.9 ± 21.0), respectively. Ignoring concentrate source, ADG (g/head/d) of R2 group heifers was only numerically higher than that of (R1) heifers (751.1 ± 17.9 vs. 720.2 ± 18.6). Average DMI (kg/head/d) was found statistically similar between T1, T2 and T3 groups (4.70 ± 0.07, 4.65 ± 0.06 and 4.71 ± 0.06). The observed DMI (kg/100kg BW) in T1 group heifers that received 40% soyaDOC in concentrate was signicantly (p < 0.05) higher than T2 and T3 group heifers (2.66 ± 0.04 vs. 2.59 ± 0.03 & 2.58 ± 0.03). There was non-signicant difference in DMI (kg/kg BW gain) of crossbred heifers fed different concentrate. Ignoring concentrate source, the observed average DMI (kg/head/d) and DMI (kg /100kg BW) in R1 and R2 was (4.57 ± 0.05 & 4.81 ± 0.05) and (2.57 ± 0.03 & 2.65 ± 0.03), respectively. DMI (kg/head/d) and DMI (kg /100kg BW) increased signicantly (p < 0.05) when a mixture of wheat straw and groundnut straw was fed to crossbred heifers. There was non-signicant difference in DMI (kg/kg BW gain) between R1 and R2 group heifers (7.33 ± 0.39 & 7.05 ± 0.22). The average serum triiodothyronine (2.69 + 0.15, 2.81 + 0.16 & 2.94 + 0.13 ng/mL) and thyroxine hormone level (52.20 ± 2.47, 57.86 ± 4.09 & 52.30 ± 2.70) of T1, T2 and T3 group heifers remained statistically similar. When the concentrate source was ignored, serum triiodothyronine was signicantly (p < 0.05) higher in R2 group heifers (2.60 ± 0.10 vs. 3.02 ± 0.13 ng/mL). The serum thyroxine concentration remained statistically similar on feeding different roughage (54.30 ± 2.16 & 53.94 ± 2.97 ng/mL). The results of the study indicate that RDDGS can replace soyaDOC fully in concentrate as a protein source and feeding mixture of groundnut straw and wheat straw is benecial in terms of growth and do not affect normal body metabolism.


Introduction
Adequate and balanced feeding of young growing heifer is essential for proper body growth and development of the mammary gland, which can improve the subsequent milk production (Harley and Loor, 2011). In developing nations, majority of livestock is owned by small and marginal farmers and balanced feeding of dairy animals is generally ignored during the non-productive growing phase due to their limited available recourses. The cost of conventional protein sources such as soybean cake and groundnut cake is high and affected by seasonal variation in availability. The scope for increasing area under fodder cultivation is limited hence; using new and alternate feed resources and the best utilization of existing feed resources are primary needs for sustainable animal production. In the last few decades, demand for ethanol is increasing in India as the clean air act amendment (1990), stresses on use of reformulated gasoline to decrease air pollutants (Chatterjee et al., 2016). The Indian government has already made it mandatory to add 10% ethanol to gasoline. The ethanol requirement will be about 12.7 billion liters by 2030 to achieve E20 (20% ethanol-blended fuel) target (Shaktivel et al., 2018). Due to limited availability of molasses, molasses alone is not su cient to meet the growing ethanol needs of the country, especially for use as a biofuel. Hence, a large number of distilleries have started cereal-grain based ethanol production. India is one of the main rice producing country and stands second after China in the world; the rice production was 168.50 MT in 2017 around 21.89% of total world rice production (Directorate of Economics & Statistics, 2019). During rice milling, around 9% of the total weight of paddy rice gets broken (Linscombe, 2006). Rice DDGS (RDDGS) is an important by-product of the distilleries (ethanol production plants) which uses damaged broken/low grade or un t for human use rice (grains) for fermentation. Nutrients are present in a highly concentrated form (approximately 3 fold) in DDGS (NRC, 1994). RDDGS contains more than 40% protein and can replace highly prized soybean meal (Yogi India is more than 100 million metric tons for both wheat straw and paddy straw. But cereal straws have low crude protein, low digestibility, less essential mineral and low voluntary intake which is one of the reasons for energy-protein malnutrition among livestock. India is the largest producer of pulses (23.24 MT) and second largest producer of groundnut (9.18 MT) (Directorate of Economics & Statistics, 2019). Cultivation of pulses and legume oilseed like groundnut for humans consumptions yield substantial amount of legume straws. Legume straw contains more CP than cereal straw and is nutritionally superior. Due to its limited and seasonal availability, its optimal inclusion rate in the cattle diet is important for its e cient utilization. Rice DDGS can be an excellent source of protein and energy, and legume straw can supply more protein than cereal straw for developing replacement heifers.
This study was planned to study the effect of feeding rice DDGS and mixture of legume and non-legume straw on growth, feed intake and thyroid hormone pro le of crossbred heifers.

Materials And Methods
Experimental location, experimental animals and duration: The present work was carried out at Livestock Research Station, College of Veterinary Science and Animal Husbandry, Anand Agricultural University, Anand, Gujarat on twenty-four HF×Kankrej (75:25) heifers with an average body weight of 116.13±4.74 kg and an average age of 281.92±13.26 days (Table 1). Prior permission was taken from CPCSEA through institutional animal ethics committee (IAEC) to perform the experiment (Project: 313/LPM/2019). The experiment started on 24 th June 2020 and ended on 9 th December 2020, with a total duration of 168 days (a total of 12 fortnights).
Experimental treatments and feeding regime: There were six experimental groups with four animals in each group. Three different concentrates containing 0, 20 and 40% rice DDGS (RDDGS) were offered to T1, T2 and T3 group heifers, respectively. Within each concentrate type, half of the heifers were offered wheat straw (R1 group) and another half a mixture of wheat straw and groundnut straw as dry roughage (R2 group) ( Table 2). Concentrate and roughage were given to the experimental heifers in the form of total mixed ration (TMR).
General Management: All the experimental heifers selected for the study were de-wormed with Fenbendazole @ 7.5mg/kg BW before the start of the experiment. They were kept under iso-managerial condition in well ventilated hygienic shed and were provided TMR ration as per treatment schedule. Animals were tied individually with a neck chain in front of the pakka manger with partitions for individual feeding.
Feeding Management: The protein requirements of the heifers under different treatment were met as per ICAR (2013) feeding standard. TMR was offered twice to experimental animals rst after tying them at their respective place between 9:00 to 9:30 hours and then between 16:00 to 16:30 hours. In addition to TMR, heifers were offered xed 2 kg/head/d and 4 kg/head/d green hybrid napier up to 100kg and above 100kg BW, respectively and with preset 35 gm/head/d mineral mixture throughout the experiment. Protein requirement of experimental heifers were adjusted at biweekly interval as per change in body weight. Feed leftover of individual heifer was weighed on the next day, when no leftover was observed, heifers were offered measured quantity of extra wheat straw so that they could complete their bulk requirement for rumen ll at 17:30 hours.
Analysis of Feeds and Fodder Samples: Representative samples of individual ingredient, concentrate and TMR offered were analyzed for proximate principle as per AOAC (2000). Details are provided in the Table No-4, 5 and 6.
Observations Recorded: Body weight: Body weight (kg) of all experimental animals was taken on the day of starting the experiment and thereafter at fortnightly interval by an electronic weighing platform in the morning hours after taking leftover and before watering and feeding.
Feed Intake: A measured quantity of TMR and green fodder were offered to the experimental heifers as per the treatment and leftover was weighed on next day morning between 7:00 to 7.30 hours. Moisture % of offered TMR, green and leftover feed was measured on biweekly basis so that actual DM consumption can be calculated. Utmost care was taken while feeding animals to get actual feed intake. Mangers were partitioned with bricks and mud keeping su cient space for individual animals. In general, there was no leftover of green as it was provided in limited quantity.

Analysis of Data
The experimental data was analyzed at Department of Agricultural Statistics, B. A. College of Agriculture, Anand Agricultural University, Anand (Gujarat) using in house tested software. Design of the experiment was RBD (factorial) and analyzed as per the statistical method described by Snedecor and Cochran (2002).

Results And Discussion
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 signi cantly (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 signi cantly (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-signi cant.
Body weight of heifers increased on replacing soyaDOC with RDDGS in concentrate and in accordance with the ndings of Eun et al. (2020), he observed signi cant (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 signi cantly (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-signi cant. Interaction of concentrate and roughage source (T×R) on ADG was found to be non-signi cant. 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 Thyroid Hormone Pro le 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 signi cant increase serum triiodothyronine concentration. The serum triiodothyronine (ng/mL) was signi cantly (p < 0.05) higher in R2 group heifers. The interaction between concentrate and roughage source (T×R) was found to be signi cant 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 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

Conclusions
Body weight and daily gain in heifers improved signi cantly when full soyaDOC in concentrate was completely replaced by RDDGS in concentrate. Feeding a mixture of groundnut straw and wheat straw in 1:1 also improved body weight signi cantly in heifers. DMI increased signi cantly on feeding mixture of wheat straw and groundnut straw over only wheat straw feeding. Serum triiodothyronine and thyroxine hormone levels of heifers were normal on feeding rice DDGS and groundnut straw. So it can be concluded that RDDGS can replace soyaDOC fully in concentrate as a protein source and feeding mixture of groundnut straw and wheat straw is bene cial in terms of growth and do not affect normal body metabolism.

Declarations
Con ict of interest: The authors declare no con ict of interest related to this study and approve their consent for publication.
Availability of data and material: The submitted manuscript is part of PhD thesis work of rst author.        Average fortnightly body weight (kg) of crossbred heifers Average fortnightly DMI (kg/100kg BW) of crossbred heifers Average fortnightly DMI (kg/kg gain) of crossbred heifers Average triiodothyronine (ng/mL) of crossbred heifers at different days of experiment Average Thyroxine (ng/mL) of crossbred heifers at different days