CHAPTER 5 THE INFLUENCE OF NUTRITIONAL LEVELS DURING POST-NATAL
5.3 MATERIAL AND METHODS
5.3.2 Experiment 1: Overwintering of lactating ewes with lambs on veld and
Lactating ewes from both Zulu sheep (n=28) with lambs (n=29), and Merino sheep (n=24) with lambs (n=37) were used in the experiment that was conducted over the winter and early spring months of July to September 2016. The lambs were born in May 2016. The animals were blocked and assigned to either the grazing maize treatment or to veld grazing for winter feeding, post-lambing. The grazing maize treatment was considered to be the high nutritive value treatment (H), and the veld to be the low nutritive value treatment (L). The treatments were replicated twice.
5.3.2.1 Animal management
The animals in this study were bred and grazed on veld for the summer preceding the trial. Pregnant ewes were moved to Kikuyu pastures prior to lambing and supplemented with Voermol Maxiwol™ production pellets at the prescribed level for the duration of the six week lambing period.
The lactating ewes and their lambs, allocated to the grazing maize treatment, were adapted as follows:
Fourteen days prior to lambing, the ewes were slowly introduced to whole grain maize.
On the first two days, the sheep were given 200 g of whole maize ewe-1 day-1, with an increase of 100 g whole maize ewe-1 every second day. By Day Fourteen the sheep were given 800 g maize grain each. This treatment continued until the lambing season was completed and lambs were strong. During this period Voermol Landelek™ was supplied at 200 g day- 1. The composition of the lick is designed to counteract acidosis.
The veld grazing groups were moved to veld camps, and their grazing was supplemented with Voermol Maxiwol™ lick in pellet form at 500 g day- 1.
96 Eragrostis curvula (Schrad.) Nees hay was supplied ad libitum to both treatments.
Fresh running water was available in all treatments. Lick and water troughs were cleaned daily.
The experiment was done during the winter months, July to September 2016, when the challenge of internal and external parasites is low and treatments for diseases are usually not necessary. For the duration of the experiment, no treatment of parasites was needed. Vaccinating with Multivax P® (vaccine) was done as prophylaxis against Enterotoxaemia (pulpy kidney), three weeks prior to starting the experiments.
5.3.2.2 Feeding treatments
5.3.2.2.1 Veld (low nutritive value treatment - L).
To determine grazing capacity a veld condition assessment was done using the method described by Camp and Hardy (1999). Based on the assessments, veld grazing camps that were rested for the full previous growing season were made available for the veld grazing treatments.
5.3.2.2.2 Grazing maize (high nutritive value treatment - H).
According to established grazing capacity norms for grazing maize, an area 4.5 ha of a maize cultivar, PAN 6P110 (a yellow medium season maize), was planted under dryland conditions during midsummer on a deep Hutton soil. Standard maize cultivation practices were applied.
Utilization of the grazing maize started on 1 July 2016. A system of strip grazing was practised by erecting temporary Bonnox fencing in strips across the maize land. This was done to restrict sheep movement and to avoid unnecessary losses of utilizable material through animal trampling. Care was taken to move sheep to the next strip in time before the quantity of the grazing became restricted.
97 5.3.2.3 Data collected
5.3.2.3.1 Forage quality Veld
To determine the herbage quality and dry matter (DM) yield of the veld, random quadrants (5 x 1 m2) were cut monthly with shearing scissors up to 5 cm above the soil surface level. The separate samples were weighed (wet weight) using an Adam LBK3 scale (https://www.adamequipment.co.za/catalogsearch/result/?q=LBK+3), and were then dried in an oven at 60ºC for 48 hours to a constant weight. The samples were then submitted to the Cedara Feed Laboratory (KZN Department of Agriculture and Rural Development) for a full feed analysis (De Figuereiro and Thurtell, (1998), according to the Goering and Van Soest (1970) methods).
Grazing maize
Sheep consume the grain, cob and maize leaves of maize plants, largely leaving the stems and roots.
To determine grain yield, a standard method of grain yield assessment was followed.
As the rows were planted 76 cm apart, a distance of 13 m was assessed for the number of cobs. The cobs were harvested, the pips removed and weighed on an Adam scale (Model LBK 3) to do a yield determination of grain production. A general maize yield equation, as described by Smith (2006), was used, which includes:
effective rainfall (ER), heat unit factor (HUF), sunshine factor (SF), soil factor (S) and management factor (MF) – using the following method:
𝒀𝒊𝒆𝒍𝒅 (𝒕 𝒉𝒂
−𝟏) = ( 𝑬𝑹
𝟏𝟎𝟎 ) × 𝑯𝑼𝑭 × 𝑺𝑭 × 𝑺 × 𝑴𝑭
For the feed quality analysis, 30 cobs were randomly harvested and the grain removed and 15 random plants were stripped of leaves. This was done randomly on five sites in the grazing maize land. Pre-grazing samples were taken monthly and submitted to the Cedara Feed Laboratory for a full feed analysis (De Figuereiro and Thurtell, 1998, according to the Goering and Van Soest (1970) methods). This exercise was repeated at the start of the months of July, August and September.
98 5.3.2.3.2 Animals
Live weight of both ewes and lambs were recorded weekly without fasting. Weighing was done in mornings between 8h00 and 10h00. The scale used was a “Tru-Test” SR 2000 (Auckland, New Zealand). The scale is accurate to 0.1 kg.
5.3.2.4 Statistical Analysis
The data on live weights of animals were analysed by using Genstat 18.1 software for Analysis of Variance (ANOVA), (VSN Int., 2015) to determine the levels of significance between the breed performances and the treatments applied. Fisher’s test of least significant differences (LSD) at a 5% level of significance was conducted.
5.3.3 Experiment 2: Post-weaning lamb performance on veld and Kikuyu