Department of Animal Science

Permanent URI for this community

https://univendspace.univen.ac.za/handle/11602/1918

Browse

Browsing Department of Animal Science by Subject "636.2340968"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Genetic Parameter Estimates of Milkability Traits in South African Holstein Cattle
    (2017-09-18) Tshilate, Thendo Stanley; Bhebhe, E.; Banga, C. B.
    Milkability, or ease of milking, is the rate at which milk can be completely drawn from a cow’s udder. It is an important functional trait with regard to milking costs as well as udder health. Milkability traits have not been included in the breeding objectives of South African dairy cattle and their genetic parameters in the population have not been estimated. The primary objective of the study was to estimate genetic parameters for milkability traits in South African Holstein cattle. Data consisted of production and milkability records of 1 532 Holstein cows, from 6 herds, participating in the South African National Dairy Animal Recording and Improvement Scheme during the period 2015 to 2016 . Measures of milkability were average milk flow (AMF), maximum milk flow (MMF) and milking time (MT). Genetic parameters were estimated by a multi-trait sire model using the Restricted Maximum Likelihood (REML) procedure. Means for AMF, MMF and MT were 1.99 kg/min, 3.02 kg/min and 5.50 min, respectively. Non-genetic factors affecting variation in milkability traits were herd-year-season of calving, parity and milk yield. Heritability estimates for AMF, MMF, and MT were 0.23±0.09, h2 = 0.41±0.12 and h2 = 0.36±0.11, respectively. Genetic correlations between the three milkability traits were medium to high, ranging from -0.35±0.23 between AMF and MT to 0.79±0.09 between AMF and MMF. Correlations were positive between AMF and MMF and negative between MT and the other two traits. There was an increase in the mean EBV for AMF of 0.002 kg/min (0.0001 kg/min per year) during the period 2002 to 2014. Maximum milk flow also showed an increasing genetic trend of 0.04 kg/min (0.0003 kg/min per year) over the same period. The genetic trend for MT was undesirable, as it increased by 0.0003 kg/min. There is scope for improving milkability through selection, in South African Holstein cattle, as indicated by the moderate to high heritability estimates. The favourable genetic correlations among milkability traits imply that selection on one trait will result in a correlated improvement in the others. Results of the current study provide a basis for including milkability traits in the breeding objective for South African Holstein cattle.
  • Thumbnail Image
    ItemOpen Access
    Immunoglobulin response and growth performance of new born Holstein calves fed Garlic (Allium savitum) powder and probiotics as feed additives
    (2015-02-18) Kekana, Thapelo Wilton; Baloyi, J. J.; Muya, M. C.
    Garlic, Allium sativum, contains secondary metabolites which promote proper immunity by stimulating the level of immunoglobulin (lg) and the efficiency of rumen function. The objectives of the study were to investigate the effects of feeding Garlic powder or Probiotics or a combination of both on level of lgG and growth performance of Holstein calves. The calves were randomly allocated, according to birth weight, to four dietary treatments, each with 8 calves. The treatments were: control, no additive (C); supplemented with either 5g/d Garlic powder (G) or 4 g/d Probiotics (P) alone or a combination of 5g/d Garlic powder and 4 g/d Probiotics (GP) with the total viable count of 1.3 x 107 cfu/g. Garlic and Probiotics were diluted in the daily milk allocation from day 4. Commercial starter feed (17.5% CP) and fresh water was available ad libitum from day 4 until day 42 of age. Calves fed G and GP had higher (P<0.05) lgG than C and P calves. Calves fed GP tended (P = 0.056) to have higher final BW compared to C (60.3 kg vs. 56.0 kg). Garlic, Probiotics or their combination did not affect (P>0.05) calves' serum glucose, heart girth (HG), average daily gain (ADG) and body length (BL). Calves in GP and P groups had lower (P<0.05) faecal score than control and garlic. The results of the current study revealed complementary effects of Garlic and Probiotics due to improved nutrients intake, body weight, and serum lgG level and reduced diarrheal incidences when fed to calves during the first 42 days of life.