The chemical compositions of normal yellow maize, QPM, paddy straw,
Dactylus glomerata with the experimental rations and that of normal maize and QPM based rations (R
1 and R
2) in terms of their dry matter, organic matter, crude protein, crude fibre, ether extract, total ash, nitrogen free extract contents with their fibre components are presented in Table 1.
The findings revealed the values of all components were within the range as reported values of Ghosh and
Bandopadhyay (2008);
Baruah et al. (2012) and
Medhi et al. (2018). It also indicated that the compositions of concentrates changes with replacement of the normal maize by QPM although their values were within the reported range of earlier workers (
Baruah et al., 2012 and
Medhi et al., 2016).
The apparent digestibility co-efficient of dry matter as well as different organic nutrients represented in Table 2 and the values were slightly higher (P>0.05) in T
2 group than T
1 fed QPM based diets replacing normal maize and the results were well matched with the findings of
Keretsu et al., 2019 in growing mithun calves.
The reason might be due to higher lysine and tryptophan content of quality protein maize in comparison to normal maize.
Tiwari et al. (2013) also revealed higher digestibility of different organic nutrients with QPM based diets in growing pigs.
Barman et al. (2020) however, observed better digestibility of different organic nutrient in growing pigs with 50 per cent but substantially reduced the values with complete replacement of normal maize with HQPM
-1 maize. The better digestibility of the nutrients with higher lysine content in the diets interferences in the gut of the animals that’s affects amino acid contents of excreta which certainly modified the nutrient digestibility of the animals (
Andrew et al., 1979 and
Short et al., 1999).
The nutritive values in terms of digestible crude protein (DCP) and total digestible nutrients (TDN) of the experimental rations without or with replacement of normal maize (R
1) through incorporation of quality protein maize (R
2) are presented in Table 3 and the values recorded were 5.11±0.52 and 58.15±0.74 and 5.43±0.42 and 59.78±1.11 percent in group T
1 and T
2, respectively. However, stati-stically the values showed no significant variations between the groups for both DCP and TDN values.
The nutritional plan of the experimental yaks in terms of DCP and TDN intake per day as well as per 100 kg body weights also indicated no significant variation between the groups and the findings were in congruence with the findings of
Medhi et al., 2018 who observed higher nutritive values with high protein diets in growing yak calves.
The average daily gain in body weights of the experimental yaks irrespective of types of maize content in their diets were very less and the reason may be the approach of adult maturity age of all the experimental animals (1
st and 2
nd pariety). However, the comparatively higher (P>0.05) gain in T2 (0.186kg±0.02) against T1 (0.175kg±0.07) as reflected in Table 3 might be due to higher protein contents with better amino acid com-positions especially the lysine and tryptophan in QPM might be the reason for better growth in T
2 than that of T
1. Similar observations were also recorded by
Medhi et al. (2018) in growing yak calves. The significant increased growth of growing mithun calves with replacement of normal maize by QPM was also found by (
Keretsu et al., 2019).
Ladely et al. (1995) also recorded nutritional benefits of high lysine corns in terms of weight gain in ruminants. Feeding the kids with high protein level along with mineral mixure had significantly increased the body weight gain, growth performance, dressing percentage, carcass yield and quality (
Muthuramalingam et al., 2018). Also,
Prakash et al. (2023) recorded iimproved feed efficiency and reduced abdominal fat with increased breast muscle in Vanaraja birds during nursery phase fed with QPM based diets.
The daily dry matter intakes of all experimental animals showed no significant differences irrespective of their diet compositions, although the values were slightly higher with QPM (5.400kg±0.21) compare to NM fed group (5.296 kg ±0.12). Accordingly, the values of per cent mean dry matter intake (DMI/100kg body weight) also varies (P>0.05) between the groups (Table 3). The efficiencies of feed intakes in the group T
2 fed QPM based diets was found significantly (P<0.05) better (29.47±0.35) than the group T
1 (31.787±0.24) fed diets with normal maize. The findings were well matched with the reported values of higher feed intake and its efficiencies with QPM based concentrates that’s have higher lysine contents in different ruminants (
Beek and Dado, 1998 and
Keretsu et al., 2019).
Barman et al. 2020 also indicated comparatively better feed efficiency in growing pigs with 50% replacement of normal maize incorporating HQPM-1 in the diets.
The balances of nitrogen in term of g/day and energy in terms Mcal/day for both Digestible Energy (DE) and Metabolizable Energy (ME) values showed no significant variations between the groups (P>0.05), however numerical variations with higher nitrogen and energy balances in T
2 group in compare to T
1 is due to higher nutrient digestibility in this group. The findings are also in congruence with the values reported by
Dado (1999);
Short et al. (1999) and
Keretsu et al. (2019).
Table 4 representing the milk yield, constituents of milk and economics of feeding in terms of Rs./litre milk/day indicated no effect of the dietary treatments in yak milk yields and its compositions and the slight increased in milk protein contents with QPM fed group might be the consequences of increased protein concentration in the diets.
Sutton et al. (1996) recorded similar effect in lactating cows based on high protein silages.
The economics on production of the yak milk calculated in terms of rupees per kg of milk yield was found to be Rs. 54.41 and 54.88 in group T
1 and T
2, respectively and it showed no significant variations between the groups indicating no effect of replacement of normal maize with quality protein maize in the diets of lactating yaks.