الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 225 |  |  |
| | | from | 225 | | |
Abstract
The records of 3691 growing Holstein Friesian calves, from birth up to weaning (born in a period from 2013 to 2019), were used in this study.
This study was conducted in a commercial farm named El-Baiomy dairy farm located in Gamasa-Dakahlia province- Egypt. This farm specialized in milk production, consisted of 2000 Frisian dairy cattle and their consequent, daily milk production ranges between 30-32 ton/day of fresh milk in average. This farm represents some modern production systems applied in Egypt that follow a widespread production pattern with special management system
In addition, a supplementary study has been made to explain management systems of calves raised in some Egyptian villages using field survey. Data of 267 questionnaires (3458 Animals) have been recorded and analyzed to study calf’s management systems in different farms located in Nile delta.
The aims of thise study was to declare the effect of dam (dry period, parity,calving interval and milk yield) and management (housing system, suckling system, season and gender) on calf performance, from birth to pweaning.
Furthermore, a supplementary study has been made to explain management systems of calves raised in some Egyptian villages using field survey. The results can be summarized as following:
• Housing calves in outdoor systems (hutches) seems to be preferable in terms of weaning weight (94.59±4.99 kg vs. 90.40±8.35 kg) and daily gain (0.79±0.07 kg/day vs. 0.77±0.11 kg/day) while weaning age (84.51±8.79 days vs. 76.46±10.64 days). Calves reared in outdoor
system were more infected with pneumonia and less infected with diarrhea than those reared in semi intdoor system.
• The best suckling system was found for calves weighing ≤ 30 kg at birth was the 1st. suckling system who showed the highest daily gain 0.85±0.19kg/day. However, calves reared under the 4th. suckling system with higher birth weight (≥ 35 kg), represents the highest daily gain (0.75±0.09 kg /day).
• There was non significant (P˃0.05) effect of season on birth weight ,however calves born in the winter had the lowest birth weight 31.34±3.86 kg, while it was been almost equal in others seasons (32±3.98 kg). However, season had significant effect on weaning weight, the highest weaning weight was been 93.88±6.53 kg in winter followed by 92.54±6.47 kg in autumn, then 91.78±8.36 kg in spring and finally 90.47±8.21 kg in summer respectively.
• There was highly significant (P˂ 0.01) effect of gender on birth weight and weaning age. The highest birth weight was been 32.93±4.04 kg in male (it was 31.63±3.81 kg in female). While weaning age was been 81.31±10.39 days and 79.14±10.71 days in female and male respectively.
• Interaction between (housing x season), (gender x suckling) and (season x suckling) were highly significant on birth weight, weaning weight, weaning age and daily gain. Interaction between (housing x gender) was significant and highly significant on weaning age and birth weight respect. These interactions emphasize the important of farm management on calves performance.
• Dry period had non-significant effect on calves performance .Calves birth weight increases with the length of cows dry period. However,
cows parities had no any significant effects on calves performance, but there was significant effect of dam calving interval on their calves birth weight.
• Milk production had non-significant effect on birth weight, weaning weight and daily gain. The lowest calves birth weight (30.40±4.59 kg) was produced by high yielder cows (>11 ton). While it was been 31.71±4.80 kg and 31.97±4.64 kg for calves belonging to cows with low (< 9 ton) and medium (9-11 ton) milk production respectively.
• Calves birth weight correlated significantly (P˂ 0.05) positive (r=0.034) with milk production of their dams.
• Birth weight correlated negatively and highly significant (P˂ 0.01) with weaning age (r=-0.080) and daily gain (r=-0.365). On the other hand it correlated positively and highly significant with weaning weight (r=0.060) respectively. On the other hand, weaning weight had highly positive correlation with weaning age (r=0.452) and daily gain (r= 0.351) respectively. While weaning age correlated negatively and highly significant with daily gain (r= -0.221).
• Winter season was associated with the highest incidence of calves diseases such as Pneumonia, Diarrhea, Arthritis, Weakness, Lameness and Eye inflammation (37.80% , 42.60%, 36.55%,40.00% ,38.98% and 31.25% respectively). However, summer season was related with Lumpy skin and Navel inflammation (63.63% and 66.66% respectively).
• Males recorded the highest incidence of diarrhea, pneumonia, lumpy skin, lameness, weakness, arthritis and eye inflammation. However, the effect of gender on diarrhea and pneumonia were significant and highly significant respectively. Otherwise there were no significant effect found between gender according to other diseases.
• Diarrhea correlated negatively and highly significant (P˂ 0.01) with pneumonia (r=-0.633), lumpy skin (r=-0.090), weakness (r=-0.176) and eye inflammation (r=-0.271) respectively. While correlated negative but only significant with navel inflammation (r=-0.067) on the other hand diarrhea non-significant negatively with lameness and arthritis (r=-0.050) respectively. However, pneumonia correlated negatively and highly significant with eye inflammation (r=-1.00) but it had positive correlation with lumpy skin (r=0.004) and weakness (r=0.010) respectively. While correlated non-significant negatively with navel inflammation (r=-0.011), lameness (r=-0.009) and arthritis (r=-0.047) respectively.
• Cows performance studied such as DP, CI, MP and prities affected seriously calves performance stieded. These cows affected farther the incidence of calves diseases.
• The majority of farmers (89.88%) rearing calves until they reach 1.5-2 years old then sold them. However, 94.76% of farmers preferred selling their calves directly after weaning while only 5.24% soled them before weaning. The majority of farmers (52.06%) utilized suckling periods up to three 3 months (68.09% of calves studied).
• Most animals (84.25 %) which had been vaccinated belonging to 70.79% of farms. However, the majority of farmers (50.19%) started feeding supplements for calves before one month of age (51.74% of calves studied). A reasonable proportion of farmers (32.58%) considered starting calves feeding in the second month.