Development and Evaluation of Straw-Based Densified Complete Feed Blocks on the Productive Performances of F1 Freisian-Borena Crossbred Dairy Cattle in the Central Highlands of Ethiopia

Abstract

The objective of the study was to assess the cureent status on utilization practices of cereal straws, followed by development and evaluation of straw-based densified complete feed blocks (DCFBs) for enhancing the use of wheat straw as feed for dairy cattle. The study assessed the current status of cereal crop residue, management, utilization practices, challenges, and opportunities, and evaluated the effect of DCFBs on feed intake, digestibility, and productive performance of crossbred lactating cows and growing heifer calves. The survey was conducted in the central highlands of Ethiopia in three purposevelly selected woredas (Welmera, Ejere and Degem) to represent wheat, tef and barley production areas, respectively. Data were collected from 180 smallholder dairy farmers (85.6% male and 14.4% female-headed households) using a structured questionnaire and personal observations. For the feeding experiments, four mid lactating multiparous cows with 2-5 parity having similar milk yield (8–10 l/d) and eight post weaned female calves with similar age (5 months) and weight (92.5±27.5 kg) were used from the F1 Friesian x Borena dairy herd found at Holetta Agricultural Research Center. Single and double 4 x 4 Latin Square Design was employed for cow and growing heifer-based experiments, respectively. In both experiments, natural pasture hay (NPH) supplemented with concentrate mix (CM) was used as a control treatment (T1). Cow concentrate mix was supplemented at a rate of 0.5 kg/liter of milk yield and calf CM was fed to cover 50% of the total feed requirement on DM base. The test diets (DCFBs) were prepared from wheat straw and the respective CM of cows and calf’s in the ratio of 50:50 (T2), 40:60 (T3), and 30:70 (T4) for both experiments. The lactating cow-based experiment lasted for 84 days, whereas that of the calves lasted for 240 days. The survey result showed as about 7.4t /HH cereal crop residues were produced per household. The entire respondents practice collection and storage of cereal residues and loose storage system under shelter-shade were practiced by about 83.5% HH. More than 68% of straws collected were used for feeding purpose only. Overall, cereal residues contribute to 75% of the basal feed proportion in the late dry season. Moistening (61.8%) with water and salt, mixing (34.4%) with market-available concentrates, molasses, and local beverage residues xviii (atella), and urea treatment (3.8%) were the common straw treatment methods used during feeding. The cluster-based farming system underway in the areas is an opportunity to increase straw yield. However, lack of appropriate processing, efficient utilization, and absence of regular training supported by practical demonstration were identified as an important challenges in their descending order. The result from the lactating cow experiment revealed that the total DM intake across all dietary treatments was similar except for cows fed with T2 diet. The OM and CP intake was observed higher (P<0.05) in T3 and T4 than T1 and T2. The NDF intake was similar (P>0.05) among the treatment diets but the highest (P<0.05) ADF intake was recorded for T1 compared to the densified complete feed block form of diets. Apparent digestibility of DM and OM were higher (P<0.05) for T3 and T4 in comparison to T1 and T2. The highest (P<0.05) CP digestibility was for T4 followed by T3 = T1 > T2. Cows in the control (T1), T3 and T4 diets digested substantially higher (P<0.05) amount of NDF as compared to those under T2 which is further comparable with T3. The ADF apparent digestibility was observed higher in T3 and T4 compared to T2 which does not varied with T1. The daily fat corrected milk yield was highest (P<0.05) for T4 followed by T3>T1=T2 diest. Similarly, cows under T4 produced higher (P<0.05) fat, protein and lactose yield followed by cows in T3 groups than the rest of the treatments. Milk fat percentages were lower (P<0.05), but milk protein percentages were higher (P<0.05) for cows under T4 than the other treatments. Feed conversion efficiency was higher (P<0.05) for cows consumed T3 and T4 diets. No difference (P>0.05) was observed in body condition scores among the treatment diets. The partial budget analysis indicated that net profit and marginal return were in a positive side for DCFBs with better return in T3. Results from the growing heifer experiment showed that the total DM and OM intake was higher (P<0.05) for T1 and T4 compared to T2 and T3. The highest (P<0.05) CP intake was recorded in case of T4 but, T1 and T3 were consumed comparable amount of CP and the least (P<0.05) intake was recorded for the T2 groups. The NDF intake for T1 and T4 was greater (P>0.05) than T2. The highest (P>0.05) ADF intake was for T2 wereas the other treatment diets showed comparable (P>0.05) ADF intake. Feed DM, OM and ADF digestibility was comparable (P>0.05) among the control, T3 and T4 but higher (P<0.05) than T2. The CP digestibility was higher in T4 (P<0.05) than the rest of the treatments. Whereas T1 was comparable to T3 and the list was recorded in T2. Simlarly, T3 and T4 showed higher NDF digestibility (P<0.05) than the T1 and T2 groups. Daily weight gain was higher (P<0.05) and xix comparable in T1, T3, and T4 diets than T2. Feed conversion ratio was higher (P<0.05) both in T3 and T4 compared to T1 and T2. The daily total cost of production was calculated lower for T3 diet with comparable growth performace to T1 and T4. In general, it can be concluded that cereal straws were an important component in basal feed for dairy cattle, although not fully exploited and require further planned intervention on appropriate storage, treatment, and processing techniques for efficient and sustainable utilization. Both experimental studies demonstrated as 40:60 proportion of wheat straw to concentrate mix was economically and biologically feasible for both lactating crossbred cows and growing heifers. Thus, it can be recommended to be used as an alternative to the hay-based conventional feeding in the urban and peri urban farming system. However, further study should be conducted to evaluate the storability and strength of the blocks under varying climatic conditions and the long-term effect of DCFB on both the productive and reproductive performance of lactating cows and growing heifers.