The study on "Effect of protein supplements of varying ruminal degradability on milk production, composition and nutrients utilization in early lactating Sahiwal cows and Nili-Ravi buffaloes" was carried out in three phases at three different experimental locations. The in situ study of animal and vegetable protein sources was conducted at the Department of Food and Nutrition, University of Veterinary and Animals Sciences, Lahore while the feeding trials with early lactating Sahiwal cows and Nili-Ravi buffaloes were carried out Government Livestock Farm, Kalurkot, Bukkar and Livestock Experimental Station, Khushab, respectively.

Different animal (n = 6) and vegetable origin (n = 15) protein sources were subjected to ruminal protein degradability analyses using the in situ technique. All these test feeds collected from ten different locations were subjected to ruminal incubation (in triplicate) for 0, 3, 6, 12, 24 and 48 h to determine the quickly soluble fraction (a), potentially degradable fraction (b), degradation rate (c) and effective degradability at different (2, 5, 8 %) ruminal passage rates. The degradability characteristics in animal protein sources (part 1, phase 1) showed significant differences in degradation kinetics and effective degradability (ED). In crude protein (CP) degradability, the quickly soluble fraction (a) was higher (P<0.05) in fish meal, PBM and meat meal and lower (P<0.05) in blood meal, feather meal and bone and meat meal. Potentially degradable fraction (b) among test feeds was maximum (P<0.05) in bone and meat meal and PBM and minimum (P<0.05) in blood meal and feather meal. The degradation rate (c) did not differ among the test feeds. Of all the animal protein sources investigated, meat meal showed maximum CP degradability at 0.05 rumen passage rate whilst, minimum (P<0.05) ED of CP was exhibited by blood meal.

Ruminal degradability characteristics in vegetable protein sources (part-2 of phase-1) showed variation in degradation kinetics and ED of CP. The quickly soluble fraction (a) was highest (P<0.05) in sesame cake and lowest (P<0.05) in CGM 60%, coconut meal and PKC. Potentially degradable fraction (b) was maximum (P<0.05) in CGM 60%, PKC, SBM and guar meal while minimum (P<0.05) in sesame cake and CGM 30%. Protein degradation rate (c) was highest (P<0.05) in CSC while lowest (P<0.05) in coconut meal, coconut cake and CGM 60%. Effective degradability of CP at 0.05 rumen passage rate was highest in sesame cake and lowest (P<0.05) in coconut meal.

All vegetable protein sources were treated (part-3 of phase-1) with formaldehyde (1 g/100 g CP) and heat treatment (1 h at 15 lb/100 g CP) to determine their effectiveness in reducing ruminal protein degradability. Both of these treatments decreased (P<0.05) rumen degradability of the vegetable protein sources investigated. Of the formaldehyde treated test feeds, quickly soluble fraction (a) was higher (P<0.05) in sesame cake and lower (P<0.05) in CGM 60%, SBM, CGM 30%, guar meal, canola meal and coconut meal. The highest value of potentially degradable fraction (b) was recorded (P<0.05) in CSC and RSC while CGM 60% had the lowest value (P<0.05). Degradation rate (c) was highest (P<0.05) in RSM, RSC, CSC, CSM coconut cake, PKC, sesame cake, SFM and CGM 60% and lowest (P<0.05) in CGM 30%, guar meal and canola meal. Effective degradability of CP was maximum in sesame cake at all the rumen passage rates. In contrast, CGM 60% had the lowest (P<0.05) ED at all of the rumen passage rates. Among the heat treated vegetable protein sources, quickly soluble fraction (a) was highest (P<0.05) in sesame cake and lowest (P<0.05) in CGM 60% and SBM. Potentially degradable fraction (b) had the highest (P<0.05) value in almond cake, RSM, RSC, CSC and SFM while CGM 60% had the lowest value (P<0.05). Effective CP degradability of the heat treated test feeds showed that almond cake and sesame cake had the highest (P<0.05) ED whilst CGM 60% had the lowest values (P<0.05). In comparing both treatments, similar influence (P>0.05) of increasing RUP level was recorded in CGM 30%, SFM, RSM, CSM, PKC and coconut meal. Formaldehyde treatment was found more effective (P<0.05) in increasing RUP level in guar meal, canola meal, RSC, CSC, coconut cake, almond cake and sesame cake whilst heat treatment increased (P<0.05) RUP level in SBM and CGM 60% at applied rates in this study.

In phase-2, a feeding trial with early lactating Sahiwal cows was conducted to investigate the effect of protein supplements of varying ruminal degradability on milk production, composition and nutrients utilization. Twenty four early lactating Sahiwal cows were selected and randomly divided into four groups. Four iso- caloric and iso- nitrogenous diets i.e., ration A (30% RUP), ration B (40% RUP), ration C (50% RUP) and ration D (60% RUP) were fed in a completely randomized design. Dry matter and CP intakes were significantly affected by ration composition (P<0.01), whereas NDF and ADF intakes did not vary among the four treatment groups (P>0.05). DM intake was higher (P<0.05) in cows receiving rations B and A than the cows fed rations C and D. There were significant differences in DM (P<0.05), CP (P<0.001) and NDF (P<0.05) digestibility due to the ration; however, ADF digestibility did not differ (P>0.05) between the rations. DM digestibility was higher (P<0.05) on ration B than rations C and D, but similar to that for ration A. Crude protein was higher (P<0.05) on rations B and A and lower (P<0.05) on rations C and D. Daily yields of uncorrected milk and protein were highest in early lactating Sahiwal cows fed ration B and lowest when fed ration D. Daily yields of 4% FCM and milk fat were higher (P<0.05) on rations B and A and lower (P<0.05) on ration D. In milk composition, fat, protein and total solids contents were the same across all diets. Nitrogen intake was highest (P<0.01) for rations B and A and lowest for ration D and C. Nitrogen balance (g/d) and as a percentage of N intake varied; with the cows consuming ration B retaining maximum (P<0.001) N. However, N balance did not vary between rations A, C and D. Nitrogen utilization was highest (P<0.001) in cows fed ration B, but there was no difference among cows fed rations A, C and D. Live weight and body condition score in cows were unaffected by the rations. Cost of milk production was least on ration B and highest on ration D.

In phase-3 a feeding trial using early lactating Nili-Ravi buffaloes was conducted. Twenty four buffaloes were selected and randomly divided into four groups. These groups were fed four experimental diets i.e., rations A, B, C and D having 30, 40, 50 and 60% RUP proportions, respectively in a completely randomized design. Results showed no differences (P>0.05) in the intakes of DM, CP, NDF and ADF intake between the rations. Likewise, DM, CP and ADF digestibility were the same (P>0.05) in buffaloes fed rations A, B, C and D; however, NDF digestibility was higher (P<0.01) on ration C and B while lowest on rations A and D. Milk yield was highest (P<0.001) on ration C while lowest (P<0.001) on rations D and A. Buffaloes given ration C produced more (P<0.05) FCM than those receiving rations A, B and D. Daily yield of milk fat was greater (P<0.001) on ration C compared to the other three rations. Milk protein yield was highest (P<0.001) on ration C and lowest (P<0.001) on rations A and C. Diet had no effect (P>0.05) on milk fat, SNF, lactose, salts and total solids percentages; whilst milk protein percentage varied among all four diets, viz ration C>ration B>ration D>ration A. Nitrogen, intake, nitrogen balance and nitrogen utilization were similar across all the diets. Live weight and body condition score in buffaloes were unaffected by the diet fed. The cost of milk production was highest (P<0.05) with rations D and B whilst lowest (P<0.05) on ration C.

It is concluded that among animal protein sources rumen CP degradability was least in blood meal and maximum in meat meal. In vegetable protein sources, coconut meal showed least ruminal CP degradability while sesame cake recorded with highest ruminal CP degradability. Both formaldehyde and heat treatments protected protein from ruminal degradability with varied levels of effectiveness in different feeds. Production performance improved with the use of RUP sources in early lactating cows and buffaloes. Sahiwal cows showed better yield performance in diets having 40% un-degradable protein in the diet, while Nili-Ravi buffaloes showed high yield performance in diets with 50% un-degradable protein sources.

The use of latest technology and methods needs to be applied for minimizing variations involved in evaluating CP degradability of feeds through in situ procedure. Influence of RDP and RUP based rations in mid and late lactation of Sahiwal cows and Nili-Ravi buffaloes are also fertile areas of research. The studies on degradability of amino acids for compiling 'internal standards' of feed resources and production performance of lactating cows/buffaloes based on ruminal degradability of amino acids rather than protein degradability would be better approach for future studies.