الفهرس 
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Abstract
The present study was carried out to evaluate the performance development in a Friesian herd raised under Egyptian condition during
eleven years starting from 2002 to 2012, which raised in Experimental
and Animal Research Unit of Toukh Tanbesha belonging to Faculty of
Agriculture, Menoufia University, (located on the road of Cairo –
Alexandria, 67 km from Cairo, Egypt). The study was performed to
estimate performance development of (herd structure, growth
performance, productive, reproductive performance, and reason of
disposal). Furthermore, some environmental factors, such as calving year,
season of calving, parity and their interactions, were also estimated. This
study covered retrospective data collected from 2250 records relevant to
950 Holstein Friesian cow recorded from years 2002 to 2012.
It could be observed that the young animals (Growing Heifers)
contributed about 42.30% of the herd size (30.29% as growing heifers
and 12.01% as pregnant heifers).Whereas the rest of the herd represents
dairy cows with 57.07%. The highest percentage of heifers (57.93 %) was
observed in year 2010 while the lowest one (24.67%) was observed in
year 2006. In year 2006 the herd was hit by many diseases which led to
the death of a large number of heifers.
The average of herd size was 412 heads per year. A gradual decrease
in the herd size could be observed from the year 2002 (660 heads) and
reached the lowest number in the year 2012 (274 heads).
Stocking density varied dramatically between years studied from
21.4 m2 per head in year 2002 to 51.50 m2 per head in year 2012.
More than 40% of the cows exist in the first parity, followed by the
second parity (23.66%) and third parity (15.27%). There are significant
differences on herd structure and farm capacity was found, which may be due to health history that the right of members of the herd, which resulted
in the presence of large disposals of the herd, whether sold as
culled or died.
Growth performance
Birth weight (BW) showed that, least squares mean ± SD of BW for
(n=2117 calves) was 34.55±5.50 kg. Year of calving and season of
calving had a highly significant effect on BW (P<0.001). Calves born
during the period of 2002-2005 were significantly (P<0.05) heavier
(34.38, 37.28, 36.30 and 36.71kg respectively) than those born during the
period of 2006-2012 (33.24, 35.18, 33.28, 33.68, 32.99, 32.49, 29.98 kg
respectively).Year 2003 had the highest value of BW (37.28 kg) while the
lowest one (29.98 kg) was represented in year 2012.
Calves born during the winter and autumn season had significantly
heavier BW (35.68 and 34.45 kg respect.) than those born during the
summer and spring season (33.67 and 34.31 kg respectively). On the
other hand parity had non significant effect (p>0.05) on BW of calves but
there seems to be a trend of increasing BW in the subsequent parity.
Weaning weight (WW), Weaning age(WA) and Pre weaning daily
gain(PWG)
Least Squares means ± SD of (WW), (WA) and (PWG) were
94.54±4.003 kg, 93.35±15.84 days and 0.672±0.10 kg/day respectively.
Year of calving had highly significant effect on all traits (P<0.01), while
the effect of season was only significant (P<0.05) on (WA), but the effect
of parities was non-significant on all traits. Productive performance
Least Squares means ± SD of (305-dMY), (TMY), (LL) and
(ADM) were 3797.61±1659.387kg, 4261.02±2065.55 kg, 353.69 ±113.51
days and 12.27±4.50kg/day respectively. The results showed also that dry
period was 92.98±47.22 days.
As showing in present study the least squares means ± SD of
productive performance were lower than the optimum value of (305-
dMY), (TMY), (LL), (ADM) and (DP) of Holstein Friesian breed .
Year of calving had highly significant effect on all productive traits
(P<0.01), while the effect of seasons was highly significant on (305-
dMY) and (ADM) and non-significant on (LL) and (DP). The effect of
parities were highly significant (P<0.01) on (305-dMY), (TMY) and
(ADM) and only significant (P<0.05) on (LL), but non-significant on
(DP). Furthermore there was specific negatively trend for the effect of
year on these traits
Reproductive performance
Least squares means ± SD of age at first calving (AFC), Service
period (SP), Calving interval (CI) and Number of services pre conception
(NSPC) were 999.97±187.16 days, 113.45±69.29 days, 474.18±108.92
days , and 2.91±2.04 services, respectively.
Year of calving had highly significant effect on all reproductive
traits (P<0.01) except (SP) which was only significant (P<0.05). Effect of
season of calving was highly significant (P<0.01) on (SP) and (CI), but
non-significant (P<0.05) on (AFC) and (NSPC). The effect of parities
were non-significant on all reproductive traits except (CI) which was only
significant (P<0.05).Reasons of disposals (ROD%)
The overall mean for disposal rate was 35.37% and ranging from
7.62 % in year 2004 to 54.71% in year 2008.
The results of (ROD %) for four seasons was observed as 42.35%,
36.04%,34.09% and 31.37% in spring followed by winter, summer and
autumn, respectively. The results of (ROD %) for first five lactations was
observed as 35.03%, 29.47%, 34.18%, 38.01%, and 49.78% respectively.
There are high percentage of voluntary culling and high percentage
of involuntary culling may be due to a lot of injuries had the impact to
reduce the numbers of animals either dies directly or because injured by
diseases which led to subsequent sold in the same year or the next one.