Mahmoud S. El-Tarabany

Reproductive performance of backcross Holstein × Brown Swiss and their Holstein contemporaries under subtropical environmental conditions.

The objective of this study was to evaluate the reproductive performance of the Holstein (HO) and their backcross HO × Brown Swiss (BS) under Egyptian subtropical conditions. The backcrosses were HBH (HO sires crossed with F1 BS × HO cows) and HHB (HO sires crossed with F1 HO × BS cows). Several reproductive indices and health traits for different genotypes were measured, and the effect of temperature-humidity index level (THI) on reproductive performance was investigated. Reproductive indices of the HHB backcross were better than those of the HO. The conception (30.1%) and pregnancy (28.9%) rates of the HHB backcross were significantly higher than those of the HO (28.1% and 22.6%, respectively). The calving interval and the days open of the HHB backcross were significantly shorter than those of the HO. The fertility of the HHB backcross was not affected by the level of the THI. The conception and the pregnancy rate of the HO decreased from 35.8% and 29.4%, respectively, at low THI to 16.1% and 12.1%, respectively, at high THI. The HHB backcross had the significant lowest incidence of retained placenta and metritis (9.6 and 16.9, respectively). In conclusion, despite their high milk production efficiency, pure HO had retarded reproductive performance and adaptability. On the other hand, the HHB backcross had a better adaptability and fertility under Egyptian conditions.

Effects of non-lactating period length on the subsequent calving ease and reproductive performance of Holstein, Brown Swiss and the crosses

The aim of this study was to evaluate the effects of the non-lactating period (NLP) length on the subsequent calving ease and reproductive performance of the purebred Holstein (HO), Brown Swiss (BS) and F1 crosses (BF) of these breeds. The NLP length was classified into four categories: D1: <45d; D2: 45-60d; D3: 60-75d; and D4: >75d. The lesser incidence of calving difficulty in the purebred HO and BF crossbred cows was recorded at D3, with no significant differences with D2 [11.6% and 9.5%; Crude Odds Ratio (COR)=1.10 and 0.84, respectively]. However, the minimum incidence of calving difficulty in the purebred BS cows was at the same NLP length with significant differences with D2 (3.8%; COR=0.31). All reproductive indices of the purebred HO cows were less as the NLP length increased. However, lesser estimates of calving interval and days non-pregnant in purebred BS and BF crossbred cows were recorded at longer (D3) NLP (350 and 328d; 112 and 133d, respectively). Purebred HO cows had decreased milk production at extremely short (D1) and long (D4) NLP. Purebred BS cows, however, were more persistent in milk production and had more consistent body condition scores (BCS). In conclusion, shortening the NLP of the purebred HO cows in addition to making minimum changes in diet composition could be an appropriate solution for improving reproduction. Purebred BS and BF crossbred cows were more persistent in milk production and tolerated the diet changes during the NLP.

Impact of thermal stress on the efficiency of ovulation synchronization protocols in Holstein cows

The objective of this study was to evaluate the impact of thermal stress on the efficiency of three different protocols to synchronize time of ovulation in purebred Holstein cows under subtropical Egyptian conditions. The influence of temperature humidity index (THI) on the conception, pregnancy, embryonic loss and early abortion rates were investigated. Conception and pregnancy rates using the CIDRsynch and Presynch (37.5% and 33.9%; 29.5 and 29. 6%, respectively) were significantly greater than that for cows expressing spontaneous estrus (SE) and with use of the Ovsynch (28.5% and 24.3%; 21.6% and 24.6%, respectively) treatment regimen. Conception and pregnancy rates using the Ovsynch protocol were significantly decreased from 31.6% and 26.3% at the lesser THI to 11.5% and 9.9%, respectively than at the greater THI [crude odds ratio (COR) = 0.28 and 0.32; P = 0.001 and 0.004, respectively]. However, conception (P/AI at 28 days) and pregnancy (P/AI at 75 days) rates using the Presynch protocol were significantly reduced at either the lesser or greater THI (COR = 0.47 and 0.42; 0.48 and 0.34, respectively). Embryonic loss rate with the Presynch group was significantly increased from 11.5% at the lesser THI to 22.2% at the greater THI (COR = 2.28; P = 0.039). In contrast, conception, pregnancy and embryonic loss rates did not differ significantly (P > 0.05) with the CIDRsynch protocol at the different THI. Results from the present study indicate that use of the CIDRsynch protocol may provide consistent and satisfactory conception and pregnancy rates in Holstein cows under subtropical environmental conditions.

Impact of three THI levels on somatic cell count, milk yield and composition of multiparous Holstein cows in a subtropical region

In Egypt, cows milk represents 52.11% of the total milk production. Climatic condition is mainly expected to impact the welfare and productive performance of livestock animals. Thus, we aimed to explore the impact of temperature-humidity index (THI) on somatic cell count (SCC), milk production and composition on daily milk test records (33600) of Holstein cows under subtropical Egyptian conditions with different levels of THI. Our results revealed that daily milk yield and composition (fat%, protein %, yielded fat, yielded protein and the percentage of lactose) were higher in low THI (31.91kg, 3.91%, 3.22%, 418kg, 349kg and 4.20%, respectively) when compared with high THI. SCC significantly increased 36% from low to high THI. In addition to, it was increased with advanced parities 231.11% from 2nd to 7th parities. At high THI level, SCC was negatively correlated with total MY (r=-0.12P<0.05), 305 MY (r=-0.16P<0.05), protein % (r=-0.15P<0.01), fat% (r=-0.14P<0.01) and lactose % (r=-0.26P<0.01). The current study concluded that dairy cows performance was better in most of the investigated parameters at low THI than those in high THI. Thus, indicating a detrimental effect of THI on both welfare and economic return.

Effect of thermal stress on fertility and egg quality of Japanese quail.

Heat stress is one of the major causes of a decreased performance of laying quail in tropical and subtropical countries. The aim of this study was to investigate the impact of temperature humidity index (THI) on fertility aspects, external and internal egg quality parameters in Japanese quail. One hundred and forty four (144) Japanese quail, 12 of weeks age, were used. Birds were divided randomly into three equal groups, control (at low THI, lower than 70), H1 (at moderate THI, 70-75) and H2 (at high THI, 76-80). Quail in the control and H1 groups had significant greater fertility (p=0.021) and hatchability % (p=0.037), compared with H2 group. Quail in the control group (at low THI) laid heavier egg weight with a higher external (egg weight (p=0.03), shell thickness, shell weight, eggshell ratio and eggshell density (p=0.001)) and internal egg quality score (albumin weight (p=0.026), yolk height (p=0.003), yolk index (p=0.039) and Haugh unit (p=0.001)). Otherwise, such quality traits were compromised in heat-stressed quail. At the high THI level, egg weight had a significant positive correlation with albumin weight (r=0.58, p<0.01), yolk weight (r=0.22, p<0.05), albumen ratio (r=0.17, p<0.05), yolk height (r=0.14, p<0.05) and yolk index (r=0.18, p<0.05), but was negatively correlated with yolk ratio (r=-0.15, p<0.05). Japanese quail exposed to heat stress (THI over 75) revealed drop in fertility indices and egg quality traits, indicating a detrimental policy of economic income.

Production and health performance of Holstein, Brown Swiss and their crosses under subtropical environmental conditions

The thermal environment is a major factor that can negatively affect milk production and health traits of dairy cows. The objective of this study was to assess the production and health traits of the pure Holstein (HO), Brown Swiss (BS), first generation crossbred (BH) and the backcross (BC) cows under subtropical Egyptian conditions, in addition to investigating the impact of temperature–humidity index (THI) on milk production traits. Pure HO, BH crossbred and BC backcross cows had significantly higher 305-milk yield (MY) (9145, 8914 and 9021 kg, respectively), and total-MY (10 694, 9845 and 10 118 kg, respectively), than pure BS. However, the BS and BH crossbred cows had significantly shorter days open (121 and 131 days, respectively), than pure HO and BC backcross cows (160 and 154 days, respectively). Furthermore, pure HO cows at greater THI had decreased daily-MY and peak-MY in a rate of 23.8% and 12.9%, respectively, compared with lesser THI conditions. In contrast, production traits of pure BS and BH cows were more adapted with conditions of heat stress, even though slight deterioration of peak-MY was recorded in BH cows, ultimately at the greater THI level. The BH crossbred had significantly lower incidence of feet problems, clinical mastitis and metritis (crude odds ratio = 0.45, 0.54 and 0.47; P = 0.027, 0.046 and 0.041, respectively), suggesting an overall amelioration in their reproductive and general health parameters in comparison with their pure HO contemporaries. Our results indicate that the first generation crossbred (BH) has a more stable production performance and adaptability than pure HO under subtropical conditions.

The efficiency of new CIDR and once-used CIDR to synchronize ovulation in primiparous and multiparous Holstein cows

The objective of this study was to elucidate the efficiency of Ovsynch protocol, new (N-CIDRsynch) and once-used (U-CIDRsynch) controlled internal drug-release (CIDR) devices to synchronize the ovulation time of primiparous and multiparous Holstein cows. The current study was performed on a total of 2207 cows using three different synchronized groups. Conception [pregnancy per AI (P/AI) at day 28] and pregnancy (P/AI at day 75) rates using the N-CIDRsynch and U-CIDRsynch regimens (35.9% and 29.6%; 29.2% and 25.1%, respectively) were significantly greater than those in the Ovsynch group [Odds ratio (OR)=1.88 and 1.44; 1.92 and 1.52, respectively]. Embryonic loss rate did not differ significantly (P>0.05) among the Ovsynch, N-CIDRsynch and U-CIDRsynch regimens. In primiparous cows, no significant differences were found in conception and pregnancy rates between the U-CIDRsynch and N-CIDRsynch groups (OR=0.95 and 1.12; p=0.693 and 0.451, respectively). In multiparous cows, conception and pregnancy rates in the N-CIDRsynch group were significantly greater than those observed in the U-CIDRsynch group (OR=0.66 and 0.71; p=0.016 and 0.027, respectively) and embryonic loss rate in multiparous cows was lower for the U-CIDRsynch treatment than for the N-CIDRsynch treated cows (COR=0.58; p=0.048). The present study indicates that the use of a progesterone device in a synchronization protocol may improve fertility in dairy cows compared to the Ovsynch treatment. The use of U-CIDRsynch regimen may achieve satisfactory fertility results compared to those reported with N-CIDRsynch in primiparous Holstein cows.

Effects of divergent selection for growth on egg quality traits in Japanese quail

The experiment was designed to investigate the impact of selection for increased body mass on external and internal egg quality traits of Japanese quail. Three hundred and sixty Japanese quail, divergently selected over three generations for different body mass at 4 weeks of age, were used. Quail were homogeneously divided into three groups each consisting of 120 birds: high body mass (HBM), low body mass (LBM) and Control. ANOVA was used to detect the effect of selection on egg quality. In addition, correlation between external and internal egg quality traits was measured. Our results revealed that HBM quail laid heavier eggs (P = 0.03 compared with LBM but not significantly different with Control quail) with a higher external (shell thickness, shell weight, eggshell ratio and eggshell density, P = 0.0001) and internal egg quality score (albumen weight, P = 0.003; albumen ratio, P = 0.01; albumen height, yolk height, yolk index and Haugh unit, P = 0.0001) when compared with both the Control and LBM. The egg surface area and yolk diameter were significantly higher in HBM when compared with the LBM but not with the Control line. Egg weight was positively correlated with albumen weight (r = 0.54, P = 0.0001), albumen ratio (r = 0.14, P = 0.05), yolk height (r = 0.27, P = 0.0001), yolk weight (r = 0.23, P = 0.002), yolk diameter (r = 0.14, P = 0.05) and yolk index (r = 0.21, P = 0.005) but was negatively correlated with yolk ratio (r = –0.16, P = 0.03). Our results indicate that selection for higher body mass might result in heavier eggs and superior egg quality.

Semen Characteristics of Purebred and Crossbred Male Rabbits

The aim of this investigation was to evaluate the semen quality traits of purebred male rabbits and their crosses under subtropical Egyptian conditions. A full 3 x 3 diallel crossing was performed for producing the first generation progeny of New Zealand White (N), Flander (F) and Rex (R) breeds. The highest ejaculate volume (p< 0.05) and percentage of live sperms (p<0.01) with the lowest percentage of sperm cell morphological abnormalities (p<0.05) had been recorded in the NF bucks. Moreover, they possessed positive estimates of direct heterosis for ejaculate volume, mass motility (Mm), individual motility (Im) and sperm cell concentration (SCC). On the contrary, pH had negative estimates of direct heterosis in all crosses and their reciprocal. Semen pH was negatively correlated with SCC (r = -0.18), Mm (r = -0.13) and Im (r = -0.23). In conclusion, the superiority of crossbreeding was particularly obvious in the New Zealand White x Flander males, which cumulated heterosis and favorable maternal effects of the Flander dams.

Effects of chronic thermal stress on growth performance, carcass traits, antioxidant indices and the expression of HSP70 , growth hormone and superoxide dismutase genes in two broiler strains

The objective was to investigate the effects of genetic type and the duration of chronic thermal stress (36 °C) on the growing efficiency, carcass traits, antioxidant status, and the expression of liver heat shock protein 70 (HSP70), growth hormone (GH) and superoxide dismutase (SOD) genes. Two hundred and seventy one-day-old chicks (135 male chicks of each breed; Ross 308 and Cobb 500) were used in this work. On the 21st day of age, birds were allocated randomly into 3 equal groups till the 42 days of age (CON:raised in a thermoneutral condition; HS1 and HS2 groups were subjected to 4 and 6 h of daily thermal stress, respectively). Regardless of genetic type, thermal stress decreased the dressing percentage in broilers when compared with the thermoneutral conditions (p = 0.039). In both broiler strains, thermal stress for 6 h (HS2) increased the heterophil to lymphocyte ratio (p = 0.036) and the serum albumin, cholesterol and triglyceride levels (p = 0.023, 0.012 and 0.005, respectively) compared with the thermoneutral group. Under the thermonuteral and heat stress conditions, the Ross broiler chickens showed a significant lower serum triiodothyronine level compared with the Cobb boilers (p = 0.042). It is interesting to note that the expression of HSP70 in the liver of heat-stressed Ross broilers, either 4 or 6 h, was significantly (p = 0.002) higher than that reported in the heat-stressed Cobb broilers. In both broiler strains, the thermal stress for 6 h up-regulate the expression of SOD gene (p = 0.001), but down-regulate the expression of GH gene (p = 0.021) when compared with the CON group. In conclusion, chronic thermal stress down-regulate the mRNA expression of liver GH, concomitantly with an increase in the expression of HSP70 and SOD genes in both broiler strains. This could be useful in the identification of molecular genetic markers to assist in selecting broilers that are more tolerant to heat stress.