Abstract
Poor reproductive
performance of cattle is a problem in many developing countries, the
major objectives of this study was to characterise the reproductive
performance of Bali cows based upon nutritional management practises
where the cattle were (i) grazing (P), (ii) were tethered in paddock
during day, tethered at the farmers house at night with grass cut
and carried and fed at night (PZ), and (iii) had zero grazing, with
all feed supplied to tethered animal via cut and carry (Z). A second
objective was to determine the major factors which influence the
reproductive performance of these animals. Cattle were identified
using ear tags or neck collars (prior to the study most animals had
no identification), aged (using their teeth) into groups (1.5 – 3
years of age; 3.5 – 5; 5.5 – 7; > 7 years of age), body condition
scored (BCS 1- 5; 1 – emaciated, 2 – lean, 3 – medium, 4 – fat, 5 –
very fat), and reproductive status assessed (lactating or not
lactating, pregnant or not pregnant). The data were collected three
times (March, July and October) over a 9 month period. Data were
analysed using SAS. Over the period the mean pregnancy was 57 %.
There were no measured seasonal effects on pregnancy rate. Cows that
were over 7 years of age (n= 25) had a higher (P< 0.01) pregnancy
rate (74%) compared to those aged 1.2 – 3 years of age (37%) (n=25).
The majority of cows had BCS of either 2 (n=162) or 3 (n=128). Five
cows had a BCS of 5 (very fat) and 10 cows had a BCS of 1
(emaciated). Pregnancy rates increased (P<0.05) as BCS increased
(37%, 50%, 64%, 73%, 63% respectively for BCS 1 – 5). Over the
9-month, 84% of the P cows, 92% of the PZ cows and 78% of the Z cows
were either pregnant and lactating or cycling at one of the three
data collections. However, the feeding system had a significant
(P< 0.05) effect on pregnancy rate, with the Z cows averaging 30%
pregnancy over the 9-month period compared to 58% for h group and
57% for the PZ cows.
|
