Data from 4143 Holstein cattle from three herds in Turkey were used to study the influences of genetic and environmental factors on milk production traits as well as genetic and environmental trends over 20 years from 1987 to 2006. First lactation mean values for 305-day milk yield, actual lactation milk yield, and lactation length were 6222±35.8 kg, 6651±42.6 kg, and 327±1.3 days. Second and third 305-day lactation yields were proportionately 8% and 11% greater, respectively. The effects of herd and calving year were the largest sources of variation for all traits. Heritabilities of actual lactation milk yield, 305-day milk yield, and lactation length for first lactation records were 0.24±0.007, 0.23±0.007, and 0.08±0.035. Estimates of variances and genetic parameters were consistent with estimates reported throughout the literature. Trends were inconsistent with some phenotypic increase in yields during the period between 2001 and 2005. This improvement was associated with increased environment parameter estimates during that period. No consistent genetic improvement was observed.

In the current paper the direct additive and maternal genetic effects on birth, weaning (at 90 days of age), and scanning (at 20 weeks of age) weights and muscle and fat depths of the ribeye area in Karayaka lambs were investigated. Analyses were carried out by the restricted maximum likelihood approach, fitting 6 animal models with various combinations of direct and maternal effects. The best model was chosen after testing for improvement in the log-likelihood values. Direct heritability (h 2 d) for all traits decreased when maternal genetic effects were included in the models. The maternal heritability (h 2 m) ranged from 0.15 to 0.22 for birth weight, from 0.04 to 0.14 for weaning weight, and from 0.08 to 0.16 for scanning weight. The effects of h 2 m on muscle depth and fat depth of the ribeye area were not considered due to their insignificance. The permanent environmental effect of the dam was significant for birth, weaning, and scanning weights. Moderate negative genetic correlations (r am) between the direct and maternal genetic effects were observed, which were significant for birth (-0.179 and-0.221), weaning (-0.310 and-0.415), and scanning (-0.116 and-0.141) weights. As a result, h 2 d and h 2 m can be used as selection criteria for birth, weaning, and scanning weights in Karayaka lambs.

________________________________________________________________________________________ KUl, E., A. ŞAHİn, S. ATASEvEr, E. UğUrlUTEpE, M. SoydAnEr: The effects of somatic cell count on milk yield and milk composition in Holstein cows. vet. arhiv 89, 143-154, 2019. ABSTrACTThis study was conducted to assess the impact of somatic cell count (SCC) on the test day milk yield (TDMY) and milk composition parameters (fat, solids-not-fat, protein and lactose) of Holstein cows raised in the Kırşehir province of Turkey. A total of 1194 raw milk samples were collected from 195 Holstein cows at different stages of lactation (from 1 to 7), parities (from 1 to 3) and calving seasons (autumn, winter, spring and summer). Also, TDMY and milk composition traits were tested by SCC in four groups (<100×10 3 , 100-200×10 3 , 201-500×10 3 and >500×10 3 cells/mL). For statistical evaluation, SCC data were converted to log 10 base. The overall means of log 10 SCC, TDMY, fat, solids-not-fat (SNF), protein and lactose were determined as 4.95 ± 0.016, 33.36 ± 0.232 kg/day, 3.39 ± 0.021%, 9.04 ± 0.013%, 3.32 ± 0.005% and 4.92 ± 0.007%, respectively. Log 10 SCC, TDMY, fat, SNF, protein and lactose were significantly affected by the stage of lactation, parity and calving seasons (P<0.05). An increase in the SCC was accompanied by a decrease in the milk yield as well as its content (P<0.05). Cows' milk with high SCC (>201×10 3 cells/mL) had a lower TDMY than milk with lower SCC (<100×10 3 and 100-200 cells/mL). However, the lowest fat, SNF, protein and lactose were determined in milk with SCC >500×10 3 cells/mL. It was concluded that SCC in milk should not exceed 500×10 3 cells/mL for Holstein cows, suggesting that monthly control of SCC may be effective for improving milk production and milk quality in Holstein cows.

Animal breeders are aware of the importance of highly nutritious and affordable animal products in the human diet and continued research in animal breeding will help ensure these needs are met. Breeding research has been conducted and will continue to be conducted in order to help reach these goals. The Brown Swiss breed is well known and used throughout the world and is an important genetic resource for Unauthenticated Download Date | 5/12/18 11:29 AM

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