الفهرس 
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Abstract
This study was carried out in the department of Genetics (Ain Shams Center of Genetic Engineering and biotechnology lab.), Faculty of Agriculture, Ain Shams University, Egypt.
Water buffaloes are the second most important species for milk production and are considered to be the key provider of meat and meat products in the world. Although buffalo milk output is lower than that of cow breeds, it has a considerably superior composition due to its high quantity of fat, protein, lactose, and minerals.
Egyptian buffaloes produce less milk and have a lower milk constituent efficiency. This production was unable to fill the population’s needs since there were no specialized breeds or lines for meat and milk. In resemblance to local cattle crossbreeding, Egyptian dairy farmers have been used to mate the pure Egyptian buffaloes (PE) with the Italian breed this was conducted to greatly improve the genetic makeup of Egyptian buffaloes for economic qualities. Imported Italian semen with these high breeding values for dual-purpose production is used
This study aimed to investigate the reproductivity and productive performance besides milk composition of buffaloes (pure Egyptian (PE)) and their crosses with Italian ones using data farm records of the previous mentioned traits. However, on the molecular level, a trial was done to find some genetic markers for the traits under study, Leptin and insulin-like growth factor (IGF) genes which potentially play important roles as markers for the identification of elite animals, which can lead to improvements in adaptability and production. where numerous economic characteristics of buffalo breeds, including energy balance, fertility, dry matter intake, weight, growth, milk yield, and milk composition, have been linked to leptin. while numerous elements of animal life, such as growth, transformation, differentiation, embryonic development, puberty initiation and progression, meat quality, and metabolism, are significantly influenced by IGF1 and its receptor (IGF1R) gene.
Ninety-nine dairy buffaloes were used as an Egyptian buffalo pure line to be compared with Egyptian-Italian crossbred buffalo (25.0% Italian, 50.0% Italian, 62.5 Italian, 75.0% Italian, 87.5% Italian and 94.0% Italian). the data were collected from United group farm for over three years and analyzed using a commercial software program. Milk production as daily milk yield, total milk yield per year, and milk composition (fat, SNF, density, and protein) The reproductive traits (birth weight, lactation length, weaning weight, Weight at 1st service, age at first calving, and number of services per conception) were recorded for all animals in the study. While on the molecular level, the genomic DNA was extracted from the whole blood, and Insulin-like growth factor (IGF) and Leptin genes were examined using polymerase chain reaction (PCR), RFLP and sequencing.
The major results of this investigation could be summarized as follows:
1- Farm data analysis showed a significant increase in all traits for the 94 % Egyptian-Italian crossbred in comparison with the PE and all other crossbreds.
2- On the molecular level all the investigated buffaloes were genotyped as BB genotype since they were negative for SnaBI restriction site at position 224^225 (TAC^GTA).
3- All the investigated buffaloes were genotyped as AA genotype since they were positive for the TaqI at position 47^48 (T^CGA) of the IGF-1R.
4- In addition, positive result was seen for the Alu1 restriction site of leptin gene and gave three products of 55, 118, and 205 bp (AG^CT).
5- Sequence analysis and alignment did not show any change in amino acid sequences among the three examined genes.
In conclusion, the obtained increase in reproductive, and productive performances which were noticed might be due to crossbreeding with the Italian buffaloes. crossbreeding needs more attention for the improvement of the genetic performance of the Egyptian buffaloes using Italian buffalo crossbreeding with the national ones. More studies are needed for the productive, reproductive, and genetic diversity of crossbred populations before enhancement of crossbreeding on the national level.