Evaluation of different straw sources and agro industrial by-products in diets of crossbred transition, lactating cows and dairy calves

Abstract

Inclusion of fiber sources in diets of all classes of dairy animals is not only essential for optimum rumen function but also beneficial in many other aspects. Three experiments were performed with an aim to evaluate the effects of feeding oat straw (OS) or wheat straw (WS) in combination with wheat bran (WB) and corn grain (CG) in diets of crossbred transition cows; replacement of conventionally used concentrate sources with palm kernal cake (PKC) in the ration of lactating cows and feeding of straw based pelleted TMR in crossbred dairy calves kept on enhaced milk feeding plan. In the first experiment twenty eight crossbred (Sahiwal x Holstein) dry pregnant cows were randomly assigned to four dietary treatments: 1) wheat straw and corn grain (WSCG), 2) wheat straw and wheat bran (WSWB), 3) oat straw and corn grain (OSCG) and 4) oat straw and wheat bran (OSWB) with n=7 animal per treatment under 2 x 2 factorial design. Experimental duration was 42 days before and 56 days after calving, conducted during hot summer months. Formulated diets were iso- nitrogenous to contain 25% WS or OS and 10% CG or WB. The cows were housed in individual free stalls and diets were fed as ad libitum TMR for 42 days pre-partum. Same lactation TMR was offered to all groups. Pre and post-partum dry matter intake percent of body weight was not affected by treatments (P>0.05). Pre-partum energy balance (EBAL) was higher for OS than WS and higher for CG as compared to WB (P<0.05). Postpartum energy balance was higher (P<0.05) in the WSCG than OSCG. Milk production and composition were not affected (P>0.05) by straw source (SS) or energy concentrate (EC). Milk yield at wk 1, 2 and 3 was higher in WSWB (treatment x wk; P<0.05) compared to the WSCG and OSWB. Total solids (TS) and feed efficiency were higher (SS x EC; P<0.05) in WSWB as compared to the WSCG. Post-partum plasma concentration of non esterified fatty acids (NEFA) was higher (P<0.05) for WS as compared to OS however the measured values were within normal limits. Post-partum plasma β-hydroxybutyrate (BHBA) concentration was not affected (P>0.05) by SS or EC. The cows fed WSWB pre-partum were in positive EBAL before and after calving which was closer to the requirements. Moreover WSWB had fewer health disorders, lower incidence of sub clinical ketosis, higher milk production and better feed efficiency during initial three wk after calving. Second experiment was conducted to evaluate the effects of increasing level of PKC in concentrate feed on DMI, BW, milk production, changes in milk composition and blood metabolites. Twenty one crossbred multiparous lactating cows with average BW of 410 ±52.6 kg, producing 12 ± 3.2 kg of milk daily were assigned to dietary treatments in randomized complete block design with seven cows per treatment. Dietary treatments were: Control (C), PKC 20 and PKC 40 containing 0%, 20% and 40% PKC in concentrate diets, respectively. The duration of experiment was 70 days including a 14 days adaptability period. The PKC was used to replace commonly used agro industrial feed ingredients like WB and rice polishing. Formulated concentrate diets were iso-nitrogenous and fed twice daily as TMR with a forage to concentrate ratio 50:50. Body weight and BCS were measured at the start and then on bi-weekly basis; whereas, feed intake and milk yield were recorded daily. Results revealed that increasing level of PKC in concentrate diet had no effect (P>0.05) on DMI, fecal score, daily milk production, BW gain and BCS gain. Similarly, milk true proteins and lactose were not affected by dietary treatments. However, milk fat and total solids increased linearly (P<0.05) with increasing level of PKC in the diets. Feed efficiency was not affected (P>0.05) by dietary treatments. In terms of blood metabolites plasma glucose, BUN and NEFA concentrations were similar among treatment. Experiment showed that Inclusion of PKC at 40% increased milk fat and total solid contents without affecting DMI, milk production, BW and BCS in crossbred dairy cows. Hence, PKC can successfully replace the conventional agro industrial by products in the xii dairy concentrate diet up to 40%. Third experiment was performed with the objective to evaluate the effects of feeding concentrate or hay based TMR in pelleted or un-pelleted form containing 85% starter and 15% oat hay (OH) in crossbred dairy calves during pre-weaning period under summer conditions. Thirty calves of 4 ± 1 days age were randomly assigned to one of three dietary treatments. Iso-nitrogenous dietary treatments were 1) conventional calf starter (CCS) without hay 2) TMR containing 85% calf starter 15% chopped OH and 3) pelleted TMR (PTMR) containing 85% calf starters and 15% OH. Colostrum fed calves were offered four L of whole milk during wk 1 and after that six L of whole milk was fed in two equal feeding in the morning and in the evening. Calves were weaned off milk gradually on the basis of targeted starter intake of 200, 600 and 800 grams after which calf was considered weaned. Feed intake and health scores were recorded daily. At the end of experiment, n=4 male calves per treatment were slaughtered for morphometric analysis. Temperature and humidity were recorded daily and were different across the wk. Results revealed that average daily DMI, average daily gain (ADG) and feed efficiency (FE) were not different (P>0.05) among the treatments. Average weaning age in PTMR was 5.4 d earlier as compared to CCS. Cost per unit gain was lower for PTMR compared with the TMR and CCS fed calves. Changes in body measurements were also not different among treatments. Blood concentration of β-hydroxybutyrate (BHBA), glucose and blood urea nitrogen (BUN) were similar (P>0.05) among treatments. Sorting activity checked after weaning revealed that calves in all the groups sorted for fine particles. Rumen development parameters including papillae length (PL), papillae width (PW), rumen wall thickness (RWT) and papillae concentration (PC) were not affected (P>0.05) by the treatments. Feeding pelleted TMR containing 15% oat hay reduced the weaning age and cost per unit gain without affecting growth performance, intake, FE and rumen development parameters. Temperature Humidity Index (THI) during experiment 1 and 3 remained over 80 which indicated significant heat stress conditions. The three studies concluded that WS combined with WB was found to be a better choice for feeding to dry crossbred cows as one group strategy during transition phase under summer conditions. Moreover PKC can successfully replace the conventional agro industrial by-products in the dairy concentrate diet up to 40%. Similarly hay based pelleted TMR can be successfully included in calf starter ration with economic benefits for crossbred dairy calves even in hot climatic conditions.